Maritimes Patrol Aircraft

December 2009
patrol aircraft (MPA) post-World War II
were primarily designed for long-range patrol to
hunt down enemy submarines. However, their
role has evolved in the late 1990s to early 21st
century to include carrying out surveillance of
the battlespace, either at sea, or even over land.
This is especially apparent in military operations
post-Sept 11, where maritime patrol aircraft of the
US and its allies were used as battlespace sur
veillance aircraft, providing information to ground
troops, taking advantage of their long range and
long loiter time capability.
Even as it transitions from submarine hunter
to multi-mission capable aircraft, the MPA still
retains its maritime roots, as even the newest
multi-mission maritime patrol aircraft are still
designed to be able to undertake anti-submarine
warfare (ASW) and anti-surface warfare (ASuW)
roles. The key to a modern maritime patrol aircraft
is flexibility, which very much depends on its
mission systems, software, communication and
growth potential.
A number of Asian countries are looking to up
grade their current fleet of maritime patrol aircraft
to reflect these changing roles, and several are
looking to procure next generation maritime patrol
aircraft altogether to replace their older maritime
patrol aircraft currently in service.
looks at
several next generation maritime patrol aircraft
currently in the market or in development.
P-8A Poseidon
The P-8A Poseidon from Boeing IDS is a long-
range anti-submarine warfare, anti-surface war
fare, intelligence, surveillance and reconnaissance
aircraft. The aircraft is designed with an advanced
mission system to ensure maximum interoper
ability in future battlespace. The P-8A Poseidon is
capable of broad-area maritime, and littoral opera
tions, and its introduction will influence how the US
Navy’s maritime patrol and reconnaissance forces
train, operate and deploy in the future.
The P-8A Poseidon is designed to be a true
multi-mission platform. Onboard P-8A, all sen
sors contribute to a single fused tactical situation
display, which is then shared over both military
standard and internet protocol data links, which
allows for seamless delivery of information
amongst US and coalition forces. The P-8A is an
armed platform, so it can independently close the
kill chain, while simultaneously providing data to
everyone on the network. The aircraft has internal
five-station weapons bay, four wing pylons, two
centreline pylons, all of which are supported by
digital stores management allowing for carriage
of joint missiles, torpedoes and mines. The P-8A
is equipped with rotary reloadable, pneumatically
controlled sonobuoy launcher. The P-8A Poseidon
has a nine-person crew, dual-pilot cockpit and five
mission crew (plus relief pilot and in-flight techni
cian). The aircraft is equipped with workstations
with universal multi-function displays, as well as
ready accommodation for additional workstation,
workload sharing.
The P-8A is a derivative of the successful and
reliable Next-Generation 737. The P-8A has the
fuselage of a 737-800 and the wings of a 737-900.
The P-8A is being developed by a Boeing-led
team that consists of CFM International, Northrop
Grumman, Raytheon, GE Aviation and Spirit
AeroSystems. Boeing provides the expertise in
customising military and commercial products
for maritime forces, and is completing the final
assembly of the P-8A in Renton, Washington.
CFM International supplies the CFM56-7 engine
that powers the P-8A, while Northrop Grumman
provides the directional infrared countermeasures
system and the electronic support measures
system. Raytheon provides the upgraded AN/
APY-10 maritime surveillance radar and signals
intelligence solutions, while GE Aviation supplies
flight-management and stores-management sys
tems. Spirit AeroSystems builds the 737 aircraft’s
fuselage and airframe tail sections and struts.
Boeing was awarded the contract to develop
the P-8A for the US Navy on June 14, 2004,
which plans to purchase 117 P-8As, with the first
test aircraft to be delivered in 2009. Initial opera
tional capability is scheduled for 2013. Boeing was
selected in January 2009 to provide eight P-8I
long-range maritime reconnaissance and anti-
submarine warfare aircraft to the Indian Navy, the
first international customer for the P-8. Interest for
the P-8A has
Maritime Patrol Aircraft
The P-8A Poseidon is a long-range anti-submarine warfare, anti-surface warfare, intelligence, surveillance and reconnaissance aircraft. It possesses an advanced mission system that ensures maximum interoperability in the future battle space. Capable of broad-area maritime, and littoral operations, the P-8A will influence how the U.S. Navy's maritime patrol and reconnaissance forces train, operate and deploy.
Nowhere to Run, Nowhere to Hide

The P-8A Poseidon is a true multi-mission platform. On board P-8A, all sensors contribute to a single fused tactical situation display, which is then shared over both military standard and internet protocol data links, allowing for seamless delivery of information amongst U.S. and coalition forces. As an armed platform, P-8A independently closes the kill chain, while simultaneously providing data to everyone on the network.
In-line Production

The P-8A is the latest military derivative aircraft to benefit from a culture of technical innovation and the One Boeing approach to manufacturing. The P-8A is a derivative of the highly successful and reliable Next-Generation 737. The P-8A has the fuselage of a 737-800 and the wings of a 737-900. Modifications to the baseline commercial aircraft are incorporated into the aircraft in-line. In the past, commercial aircraft were sent to modification centers where they were taken apart and rebuilt to meet military specifications. The P-8A is Boeing's first military derivative aircraft to incorporate structural modifications to the aircraft as it moves through the commercial line.
Boeing's team is developing the P-8A Poseidon for the U.S. Navy, which plans to purchase 117 aircraft. As part of the flight test program, the Navy will have three P-8As at Naval Air Station Patuxent River, Md., in 2010. Initial operational capability is scheduled for 2013. In January 2009 Boeing was selected to provide eight P-8I long-range maritime reconnaissance and anti-submarine warfare aircraft to the Indian navy. India is the first international customer for the P-8. Boeing believes there are numerous other opportunities for international sales to countries currently operating P-3s or similar maritime patrol aircraft. Interest has been expressed by many countries including Australia and Italy.
The Poseidon Industry Team

The P-8A is being developed by a Boeing-led team that consists of CFM International, Northrop Grumman, Raytheon, GE Aviation and Spirit AeroSystems.

An industry leader in large-scale systems integration, Boeing provides unrivaled expertise in customizing military and commercial products for maritime forces. Boeing is completing final assembly of the P-8A in Renton, Wash., taking advantage of the proven efficiencies, manufacturing processes and performance of the existing Next-Generation 737 production system.

CFM International supplies the CFM56-7 engine that powers the P-8A.

Northrop Grumman provides the directional infrared countermeasures system and the electronic support measures system.

Raytheon provides the upgraded AN/APY-10 maritime surveillance radar and signals intelligence solutions.

GE Aviation supplies flight-management and stores-management systems.

Spirit AeroSystems builds the 737 aircraft's fuselage and airframe tail sections and struts.
Since the System Development and Demonstration contract was awarded to Boeing in 2004, the P-8A Poseidon program has been a model acquisition program.
First flight — 2009
First flight test aircraft to Naval Air Station Patuxent River, MD. — 20101_ad_aew_000821_media.jpgThe EMB-145 AEW&C is a derivative of the Embraer ERJ-145 regional jetliner airframe, modified with the integration of an airborne early warning radar and mission system.

The aircraft incorporates a reinforced airframe, new navigation and communication systems, an enhanced auxiliary power unit (APU), increased fuel capacity and a revised interior layout.
EMB-145 AEW&C's Ericsson ERIEYE radar

The EMB-145 AEW&C's mission system is developed around the Ericsson ERIEYE active, phased-array pulse-Doppler radar and is integrated with an onboard command and control system. Electronic surveillance measures for monitoring communications and non-communications activities are also integrated with the system.

In 1997, Embraer was awarded a contract to develop and produce the ERIEYE-based EMB-145 AEW&C (designated R-99A) aircraft, together with another version of the same aircraft, the EMB-145 RS remote sensing (designated R-99B) variant, for the Brazilian Government's SIVAM programme.
EMB-145 Erieye AEW&C orders and deliveries

The Brazilian Air Force (FAB) ordered five AEW&C and three EMB-145 RS aircraft. The first AEW&C aircraft was delivered to the Brazilian Air Force in July 2002 and deliveries were completed in December 2003.

The Hellenic Air Force of Greece has ordered four EMB-145 AEW&C. The first was delivered in December 2003 and deliveries completed in May 2005. Mexico has ordered one aircraft for border and coastline monitoring which was delivered in June 2004. Erieye radar systems have also been ordered by Sweden. In February 2005, Embraer signed a memorandum of understanding with India for the procurement of three systems.
In July 2008, a deal was finally signed, under which Embraer will supply three ERJ-145 aircraft and perform the modifications required to carry the active array antenna unit (AAAU) AEW&C system developed by India's Centre for Airborne Systems (CABS) of Defence Research and Development Organisation (DRDO). The first EMB-145 aircraft completed its maiden flight in December 2011. It was delivered to the Government of India in August 2012. The aircraft will subsequently be delivered to the Indian Air Force after the installation of DRDO missions systems in India.A fleet of three aircraft is sufficient to sustain two airborne patrols around the clock for a limited time, or one airborne patrol with one aircraft on continuous ground alert for more than 30 days. Although capable of long endurance at normal patrol speeds, the EMB-145 has a high dash speed which contributes to survivability on patrol missions.
The EMB-145 AEW&C crew includes the pilot and co-pilot, five mission systems specialists and up to three reserve crew members. The aircraft is equipped with five or six mission operator consoles.

The all-glass cockpit is fitted with five displays – primary flight displays, multi-function displays and the engine indication and crew alerting system (EICAS) – with multi-reversionary capabilities.

Avionic systems include full TACAS II (traffic alerting and collision avoidance), a ground proximity warning system (GPWS) and windshear detector. Dual digital air data computers drive the attitude and heading reference system (AHRS).

The pilot is provided with a head-up display particularly for landing guidance. The aircraft has two radio altimeters and an instrument landing system. A dual integrated computer controls the autopilot flight director (APFD), windshear detector and EICAS.
ERIEYE active, phased-array pulse-Doppler radar

ERIEYE has been developed by Ericsson Microwave Systems. The system comprises an active, phased-array pulse-Doppler radar including integrated secondary surveillance radar and identification friend or foe (SSR/IFF), a comprehensive, modular command-and-control system, electronic support measures (ESM), communications and datalinks.
"ERIEYE comprises an active, phased-array pulse-Doppler radar."

Rather than conventional rotodome antenna system, ERIEYE has a fixed, dual-sided and electronically scanned antenna mounted on top of the fuselage. This places much less demand on aircraft size and is designed for mounting on commuter-type aircraft. The ERIEYE is capable of 360° detection and tracking of air and sea targets over the horizon. The instrumented range is 450km and a typical detection range against a fighter aircraft size target is in excess of 350km.

The system uses advanced solid-state electronics, open-system architecture and ruggedised commercial off-the-shelf (COTS) hardware, including general-purpose programmable workstations and full-colour LCD displays. The ERIEYE radar is already in service with the Swedish Air Force and is in series production for Brazil and other customers.
SIVAM Amazon Basin survey programme

The SIVAM programme is designed to survey the entire Amazon Basin, an area considerably greater than that of Western Europe. Eight aircraft, five for surveillance and three for remote sensing are used for environmental protection, natural resources survey, border surveillance and support of sustained development in the Amazon region. The aircraft are operated by FAB from the Annapolis air force base.
The EMB-145 RS remote sensing aircraft is equipped with synthetic aperture radar, forward-looking infrared / television (FLIR/TV), multi-spectral scanner, COMINT communications intelligence suite, ELINT electronics intelligence system and an on-board recording and processing system. The RS aircraft will be capable of providing updated mapping information and imagery of the area.
Q-Series aircraft from Bombardier SpecialisedMRMR8.jpg
Aircraft Solution (SAS) provide the endurance
and flexibility needed to loiter in a given area
or shadow a target for longer periods of time.
Ideal for maritime patrol, the rugged and reliable
Q-Series aircraft is used around the globe for
coastal surveillance, air and marine interdiction,
and airspace security. The Q-Series is a family of
turboprop passenger aircraft outstanding by its
durability and low noise emission.
The latest addition to the Q-Series is Q400 with
a greater seating capacity, higher cruise speed of
360 knots, longer fuselage and longer range. The
Q400 turboprop aircraft is powered by two Pratt
& Whitney Canada PW150A rated at 1,846kW
each. The propulsion system includes two high
efficiency Dowty Aerospace all-composite, six-
bladed propellers.
The engines are the key for the Q400’s bet
ter performance compared with other Q-Series
aircraft and the majority of existing turboprop
aircraft. The Q400 is available in three models
with different maximum gross weight and payload
capacity. Apart from maritime patrol, the multi-role
Q400 can be configured for high altitude surveil
lance and domain awareness; command, control
and communications and tactical and strategic
Saab%202000%20SIGINT%20-%20Saab_edited-1-thumb-450x318-47264.jpgThe Saab 2000 AEW&C airborne early warning and control aircraft is a variant of the Saab 2000 regional transport turboprop aircraft equipped with the spine-mounted Saab Systems Erieye PS-890 side-looking reconnaissance radar.

The first customer for the Saab 2000 AEW&C, the Pakistan Fiza'ya (the Pakistan Air Force), placed the order with Saab, based in Stockholm, in June 2006 for Skr6.9bn. The Government of Pakistan renegogiated part of the contract in May 2007 due to financial crisis within the country. The contract value was reduced to Skr1.35bn.

The first of four aircraft was rolled out in April 2008 and entered into service in October 2009. The second aircraft was delivered to Pakistan in April 2010 to monitor Indian airspace. Thailand announced the selection of the Saab 2000 AEW&C in June 2007.

The aircraft, fully equipped for airborne early warning and control, can also be used for national security missions, border control, airborne command and control, disaster management coordination and for emergency air traffic control.
"The Saab 2000 airborne early warning and control aircraft is a variant of the Saab 2000 regional transport turboprop aircraft."
Saab 2000 AEW&C programme

Saab Surveillance Systems is the lead contractor for the Saab 2000 AEW&C programme. Saab Aerotech is responsible for the development and modification of the Saab 2000 regional aircraft to the AEW&C configuration. Six other Saab business units are also contracted for major elements of the programme.

The outer wing sections have been strengthened, as has the roof of the fuselage, to accommodate the weight of the Erieye antenna and its housing. The vertical tail area has been increased to provide improved stabilisation.
Main cabin
The main cabin is fitted with five mission operator consoles on the starboard side.

The windows on the starboard side of the main cabin have been removed. The cabin is air-conditioned and fitted with an active noise cancellation system.

The aft section of the main cabin accommodates fuel tanks and mission equipment. Two auxiliary fuel tanks are installed on the starboard side in the mid fuselage section immediately aft of the mission consoles.

The mission operator consoles perform: system and sensor management; mission planning and simulation; track data processing; asset management and control; identification and allocation. The display systems incorporate digital maps and use high-resolution flat-panel colour displays and touch input display controls. The main cabin aft section also accommodates the electronic warfare equipment, the Erieye equipment and the Erieye power units.
Erieye surveillance radar

Saab Microwave Systems (formerly Ericsson) is the lead contractor for the Erieye surveillance radar. The Erieye radar is operational on a number of other aircraft including the Saab 340, Embraer R-99 and Embraer EMB-145. Erieye is an active phased array pulse Doppler radar operating in the 3.1GHz to 3.3GHz band. The radar is operational from three minutes after take-off and during climb and provides an effective surveillance area of 500,000km².
"The main cabin is fitted with five mission operator consoles on the starboard side."
The Erieye radar has an instrumental range of 450km and detection range of 350km against a fighter aircraft sized target in dense hostile electronic warfare environments and at low target altitudes. The system is capable of tracking multiple air and sea target over the horizon and provides above 20km altitude coverage, 360° coverage and has sea surveillance capability. The radar incorporates an identification friend or foe interrogator. The system comprises an active phased array pulse Doppler radar with a secondary surveillance radar.

The fixed dual sided electronically scanned antenna array is installed in a rectangular housing, dorsally mounted above the fuselage.
Electronic warfare suite

The aircraft's electronic warfare suite is based on the Saab Avitronics HES-21 electronic support measures (ESM) and self-protection suite. The HES-21 also provides a ground-based support system (EGSS), which provides mission data for the aircraft electronic warfare system and for analysis of recorded data.
Electronic support measures

The electronic support measures (ESM) system comprises digital narrow band and wide band receivers and associated antennae, providing close to 100 % probability of intercept (POI). The digital receiver is equipped with interferometer antenna arrays.
The ESM obtains the electronic order of battle (EOB) data and intercepts, characterises and identifies signals, defines their direction of arrival, generating and displaying warning information. The ESM system operates autonomously and allows real time ESM analysis and presentation to the ESM operator on board the aircraft. ESM data is recorded during missions for post mission tactical and technical analysis. Information is transferred to other onboard systems including the command and control system and the radio data link-controller.

The radar receivers cover low band (7GHz to 2GHz), mid band (2GHz to 18GHz) and high band (28GHz to 40GHz).

The digital RF receiver provides very high sensitivity and selectivity and uses fast Fourier transforms (FFT) and channelisation signal processing techniques. The ESM's wide band and narrow band receivers provide 360° coverage, and close to 100% probability of intercept. The system provides high sensitivity and selectivity in dense and hostile signal environments.
Self-protection system

The self-protection system (SPS) comprises: defensive aids control system, radar warning, laser warning, missile approach warning and chaff and flare dispenser systems. The self-protection suite provides selection and, in automatic mode, the initiation of the chaff and countermeasures sequences.
"The Erieye radar has an instrumental range of 450km and detection range of 350km."

The laser warning system is based on the Saab Avitronics LWS-310 laser warner operating in the 0.5 to 17 microns wavelength bands. Spatial and spectral coverage is provided by an array of three sensors on each side of the aircraft.

The missile launch and approach warner (MAW) is based on the Saab Avitronics MAW-300, which can simultaneously monitor and track up to eight threats. It has four sensors, two on each side, and each with 110° azimuthal coverage to provide the overlapped 360° spatial coverage.

The chaff and flare dispensing system (CFDS) comprises a dispenser control unit, (CFDC) with a cockpit mounted display and control panel, defensive aids suite computer with a threat library database, two BOL electromechanical dispensers and six BOP pyrotechnical dispensers.

The BOL dispenser is a high-capacity, 160-cartridges, electro-mechanical chaff dispenser. The BOL dispensers are installed in the fairings under the wingtip-mounted radar warning pods. The dispenser incorporates vortex generators which provide chaff blooming characteristics and a chaff cloud Doppler response.

The BOP dispenser is a pyrotechnic dispenser carrying Nato standard rectangular cartridges or magazines of 39 1in² cartridges. The dispenser has the capability to dispense different ammunition types concurrently. The BOP dispensers are housed on each side of the underside of the fuselage to the aft of the wings.

The aircraft is fitted with two Rolls-Royce AE 2100A turboprop engines developing 3,095kW. AE 2100A is a two shaft gas turbine engine equipped with a 14-stage high pressure (HP) compressor driven by a two-stage HP turbine. The engine also features a planetary reduction gearbox connected to the propeller. It also features a full authority digital engine control (FADEC) to manage both engine and propeller.

The length and diameter of the engine are 11.8in (0.29m) and 19in (0.48m) respectively.
Saab 2000 performance

The aircraft can climb an altitude of 9,144m in 15 minutes. The maximum cruise and patrol speed of the aircraft are 629km/h and 296km/h respectively. The range is 3,218km. The take-off run of the aircraft is 1,400m and the maximum endurance is 9.5 hours. The aircraft weighs around 14,500kg and its maximum take-off weight is 23,000kg.
C29%20Persuader.jpegThe C-295M is EADS CASA (now Airbus Military) twin-turboprop transport aircraft developed by the former Construccionnes Aeronáuticas SA (CASA), based in Madrid and a founder member of the EADS company.

The new C-295 is a stretched derivative of the CN-235 transporter, with characteristic high-wing, rear-loader design. The aircraft is noted for its short take-off and landing capability on semi-prepared runways and for the large payload capacity of 9,250kg. The landing and take-off run of just 320m and 670m allow the aircraft access to runways close to operational or crisis areas or where supplies and troops are needed.
C-295M transport aircraft programme

CASA announced the aircraft in June 1997 at the Paris Air Show at Le Bourget and the first production C-295 made its first flight in 1998. The aircraft was granted INTA certification for military operations, and DGAG and FAA (FAR part 25) certification in 1999.

In 1999, the Spanish Ministry of Defence placed a contract for nine C-295M transport aircraft. The aircraft entered service with the Spanish Air Force in November 2001 and delivery of the aircraft completed in 2006. A further two aircraft were ordered in 2005, two in 2006 and two in 2007 to bring the fleet to 15.
International orders and deliveries

International orders include: Air Force of Poland (eight - deliveries complete), United Arab Emirates Navy (four for maritime patrol), Brazilian Air Force (12 to support the SIVAM Amazon monitoring project, first delivered in October 2006), Swiss Air Force (two), Royal Jordanian Air Force (two), Algerian Air Force (six) and the Finnish Air Force (two).
In April 2005, Venezuela ordered ten C-295 transport aircraft, but the USA denied the export licence necessary for the American content of the aircraft and the order has been revoked. In February 2006, Portugal ordered 12 C-295 aircraft, seven for military transport and five for maritime surveillance. Deliveries began in November 2008 and have been completed.
Poland ordered an additional two aircraft in October 2006 (delivered in September 2007) and two in October 2007 (to be delivered in 2009) to bring its fleet to 12 aircraft. Five more aircraft, worth $262m, were ordered in July 2012. The first two were delivered in October 2012 and the third in December 2012. The remaining aircraft will be delivered by the end of 2013.
In October 2007, the Chilean Navy purchased three aircraft. The Colombian Air Force ordered four aircraft in November 2007. The first two deliveries were made in June 2008, while the third and fourth were delivered in November 2008 and April 2009 respectively. Two more aircraft were ordered, one in September 2012 and the other in January 2013. These are scheduled to be delivered in 2013.
The Czech Air Force ordered four C-295 aircraft in May 2009. Deliveries began at the end of 2009 and concluded in 2010.

EADS CASA was teamed with Raytheon to offer the C-295 combined with the CN-235-300 for the US Army / Air Force joint cargo aircraft (JCA) competition. The C-27J was chosen in June 2007.

In February 2012, Indonesia placed an order for nine C-295 aircraft. The first two were delivered to the Indonesian Air Force in September 2012. The remaining aircraft will be delivered by 2014.

In March 2012, Kazakhstan's Ministry of Defence placed an order for two aircraft. A Memorandum of Understanding (MoU) was also signed for six additional aircraft. Kazakhstan took delivery of the first two C295s in January 2013.

In May 2012, Airbus Military received an order from Oman for the delivery of C-295 aircraft in tactical transports (five) and maritime patrol aircraft (three) configurations. The deliveries are scheduled for completion in 2013.

Egyptian Air Force ordered six C295 transport aircraft in January 2013. The aircraft will be delivered from late 2013.
C-295M cockpit

The flight deck is fitted with dual controls for the pilot and co-pilot. The aircraft is equipped with fully digital integrated TopDeck avionics suite supplied by Thales. The displays, including four 152mm x 203mm (6in x 8in) Thales colour liquid crystal displays, are compatible with Night Vision Goggles (NVG).
"C-295M has short take-off and landing capability on semi-prepared runways."

The maritime patrol variant (MP Persuader) can be fitted with EADS CASA FITS mission system.

Aircraft for the UAE Navy are fitted with FITS, which consists of four multi-function consoles and integrates data from sensors including search radar, forward-looking infrared (FLIR), TV cameras or other sensors.

Two head-up displays can also be fitted as an option.

The communications suite includes two or three UHF/VHF radios, a single or dual HF radio and an audio control system. The C-295 is also fitted with a cockpit voice recorder (CVR), identification friend or foe (IFF) system, the flight data recorder (FDR) and an emergency locator transponder (ELT).

The aircraft is equipped with a dual Thales flight management system, controlled through two multifunction controller display units (MCDU), dual air data units type ADU 3000 from Thales, dual attitude heading and reference systems (AHRS), manufactured by Thales, two radar altimeters (radalt) and an optional Honeywell ground proximity warning system.

Other navigation equipment includes two multimode receivers (MMR), two automatic direction finders (ADF), one direction finder (DF) and two distance measuring equipment (DME) units. There are also three possible configurations for long-range and autonomous navigation: two integrated inertial navigation and global positioning systems (INS/GPS), two GPS or two GPS plus one INS/GPS.

The colour weather radar, a Honeywell RDR-I400C, has search, beacon and vertical navigation ground mapping modes. Portuguese Air Force C-295s are fitted with Northrop Grumman AN/APN-241 colour weather radar.

The aircraft can be fitted with alternative communications and navigational systems to suit the customer country's operational requirements. Optional equipment includes an enhanced terrain collision avoidance system (TCAS), tactical air navigation (TACAN), category II instrument landing system, a microwave landing system and satellite communications.
"The C-295M is EADS CASA twin-turboprop transport aircraft."

The main cabin can be fitted with two or three rows of foldable seats to accommodate 48 fully equipped paratroops or up to 75 troops. There are two paratroop doors, one on each side at the rear part of the cabin. The cabin is fully air conditioned and pressurised.

The cabin can be configured for medical evacuation missions for 27 litters (stretcher patients) and four medical staff. An alternative configuration accommodates an intensive care unit for 12 stretcher patients.

The cabin can be fitted for mixed cargo and passenger transport, or for all cargo operations. A roller loading system is installed and a wide ventral door and cargo ramp in the upswept rear fuselage provide easy cargo access.

The cabin holds up to 57m³ of cargo and can accommodate up to three light vehicles, Land Rovers or equivalent, or five 2.24m × 2.74m (standard 88in × 108in) pallets.

The C-295 can be fitted with the Indra ALR-300V2B radar warner and BAE Systems ANALE-47 chaff / flares dispenser.
C-295M engines

The aircraft is powered by two Pratt & Whitney Canada PW127G turboprop engines, each rated at 1,972kW and at 2,177kW with auto power reserve. The engines drive six-bladed composite propellers, type HS-568F-5 developed by Hamilton Sundstrand. The blades, of 3.89m diameter, have autofeathering and synchrophasing.
"The cabin holds up to 57m³ of cargo."

The aircraft carries a 7,700l fuel load, giving a maximum range of 5,630km.

The aircraft can be equipped with an optional probe for probe and drogue refuelling, so the range can be extended by in-flight refuelling.
Landing gear

The aircraft is fitted with tricycle-type retractable landing gear designed by Messier-Dowty. The landing gear is designed to allow operation from semi-prepared runways, down to runway class CBR-2, and is equipped with levered suspension and oleo-pneumatic shock absorbers.
The main landing gear, each equipped with two wheels in tandem, is installed in fairings on the underside of the fuselage. The gear is fitted with Dunlop hydraulically operated differential disc brakes and an anti-skid system. The steerable nose wheel is fitted with twin wheels.
Developed by Alenia Aermacchi, the ATR 72 ASW is the most affordable solution to fulfill the Anti-Submarine role in modern naval warfare.

Proven in revenue service under a wide range of operating conditions, the ATR 72 is well adapted to ASW missions as a result of its design and size which provide a solid airframe, the necessary support systems, and the cabin volume to accommodate the special equipment required to search for, detect, identify, track, and attack both submarines and surface targets on command.

AIR_ATR-72_ASW_Concept_lg.jpgThe ATR 72 ASW integrates the tactical patrol and surveillance mission system of the ATR 42 Surveyor with additional anti-submarine warfare capabilities such as a search radar, an acoustic system with sonobuoy launcher, an electro-optic system, a Magnetic Anomaly Detector (MAD), a self protection system including Electronic Support Measures (ESM), Missile Warning System (MWS), chaff and flare dispensers and an armament system with four underfuselage pylons for depth charges, torpedoes and antiship missiles.

The ATR 72 ASW has been recently selected by the Turkish Government to be operated by the Turkish Navy.

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Span 27.05 m 88.75 ft
Length 27.17 m 89.13 ft
Height 7.65 m 25.08 ft
Wing area 61 sqm 657 sqft
Empty 15,052 kg 33,184 lb
Takeoff (maximum) 21,960 kg 48,413 lb

Power Plant
Take-off power 2,475 SHP
Take-off power 2,750 SHP
Propeller (Hamilton Sundstrand) 6 Blade 568F
Performance (clean, ISA)
Balance take-off field length (ISA - Sea Level MTOW) 1,290 m 4,232 ft
Landing Field Length (Sea level -MLW) 1,067 m 3,500 ft
Maximum Cruise Speed (97% MTOW - ISA - 16,000 ft) 276 kt
The ATR 72 is a twin-engine turboprop short-haul regional airliner built by the French-Italian aircraft manufacturer ATR. A stretched variant of the ATR 42, the aircraft seats up to 78 passengers in a single-class configuration, and is operated by a two-pilot crew.

1 Development
2 Design
3 Variants
3.1 ATR 72–100
3.2 ATR 72–200
3.3 ATR 72–210
3.4 ATR 72–500
3.5 ATR 72–600
3.6 Other versions
4 Specifications (ATR 72 500)(ATR 72 600)
5 Operators
5.1 Former civil operators
5.2 Military operators
6 Accidents and incidents
7 See also
8 References
8.1 Notes
8.2 Bibliography
9 External links


The ATR 72 was developed from the ATR 42 in order to increase the seating capacity (48 to 78) by stretching the fuselage by 4.5 metres (15 ft), increasing the wingspan, adding more powerful engines, and increasing fuel capacity by approximately 10 percent. The 72 was announced in 1986,[4] and made its maiden flight on 27 October 1988. One year later, on 27 October 1989, Finnair became the first airline to put the aircraft into service.[5] Since then, at least 408 ATR 72s have been delivered worldwide with orders pending on at least 28 more.
Aer Arann ATR 72 on take off

Passengers are boarded using the rear door (which is rare for a passenger aircraft) as the front door is used to load cargo. Finnair ordered their ATR 72s with a front passenger door so that they could use the jet bridges at Helsinki–Vantaa airport. Air New Zealand's standard rear door aircraft can use jet bridges at airports with this equipment. A tail stand must be installed when passengers are boarding or disembarking in case the nose lifts off the ground, which is common if the aircraft is loaded or unloaded incorrectly.

The ATR aircraft does not have an auxiliary power unit (APU) as normally equipped. The APU is an option and would be placed in the C4 cargo section. Most air carriers normally equip the aircraft with a propeller brake (referred to as "Hotel Mode") that stops the propeller on the #2 (right) engine, allowing the turbine to run and provide air and power to the aircraft without the propeller spinning. The downside to the prop brake is improper usage; many airlines have burned out these brakes, so some companies have removed them from the aircraft entirely.[citation needed]
ATR 72–100

Two sub-types were marketed as the 100 series (−100).

ATR 72–101
Initial production variant with front and rear passenger doors, powered by two PW124B engines and certified in September 1989.
ATR 72–102
Initial production variant with a front cargo door and a rear passenger door, powered by two PW124B engines and certified in December 1989.

ATR 72–200
Aurigny Air Services ATR 72–200 lands at Bristol Airport, England

Two sub-types were marketed as the 200 series (−200). The −200 was the original production version, powered by Pratt & Whitney Canada PW124B engines rated at 2,400 shp (1,800 kW).[6]

ATR 72–201
Higher maximum take-off weight variant of the −101, a PW124B powered variant certified in September 1989.
ATR 72–202
Higher maximum take-off weight variant of the −102, a PW124B powered variant certified in December 1989.

ATR 72–210

Two sub-types were marketed as the 210 series (−210), the −211, (and with an enlarged cargo door, called the −212), is a −200 with PW127 engines producing 2,750 shp (2,050 kW) each for improved performance in hot and high-altitude conditions. Difference between the sub-types is the type of doors, emergency exits.

ATR 72–211
PW127 powered variant certified in December 1992.
ATR 72–212
PW127 powered variant certified in December 1992.

ATR 72–500
A CCM ATR 72–500 during boarding, showing the front cargo hold, rear passenger integrated stairway, and parking tail stand.

ATR 72-212A
Marketed as the −500 and certified in January 1997 with either PW127F or PW127M engines the −212A is an upgraded version of the −210 using six-bladed propellers on otherwise identical PW127F engines. Other improvements include higher maximum weights and superior performance, as well as greater automation of power management to ease pilot workload.

ATR 72–600
An Air Nostrum ATR-72-600 climbing after take-off

The –600 series aircraft was announced in October 2007; the first deliveries were planned for the second half of 2010.[7][8]

The new ATR 42–600 and 72–600 feature a number of improvements over previous versions. They are powered by the new PW127M engines, which enable a 5% increase in takeoff power called for by a "boost function" as needed, only when called for by the takeoff conditions. The flight deck features five wide LCD screens (improving on the EFIS from previous versions). A multi-purpose computer (MPC) aims at increasing flight safety and operational capabilities, and new Thales-made avionics provide RNP capabilities. Finally, the aircraft feature lighter seats and larger overhead baggage bins.

The prototype ATR 72–600 (registered F-WWEY[9]) first flew on 24 July 2009; it had been converted from an ATR 72–500.[10]

The ATR 72–600 Series launch customer is Royal Air Maroc Express. Air New Zealand announced in October 2011 that it would purchase 12 new ATR 72–600 to add to their 11 ATR 72–500 regional Mount Cook Airlines fleet. Colombia and El Salvador airline Avianca-TACA signed a contract for 15 ATR 72–600 in December 2012, with an option for 15 airplanes more, to replace older Fokkers.[11] The largest –600 operator is Azul Brazilian Airlines, with 18 aircraft in its fleet.

NOTE: According to the ATR42 & 72 EASA Type Certificate Data Sheet TCDS A.084, Iss 3, 17-10-2012,[12] "ATR 72-500" and "ATR 72-600" are the manufacturer's marketing designations of ATR 72-212A aircraft model with certain options installed. These marketing designations are not recognised by EASA as any new certified aircraft model or variant, and must not be used on ATR certified/approved documentation, where only ATR 72-212A must be indicated.
Other versions


Bulk Freighter (tube versions) and ULD Freighter (Large Cargo Door). ATR unveiled a large cargo door modification for all ATR 72 at Farnborough 2002, coupled with a dedicated cargo conversion. FedEx, DHL, and UPS all operate the type.[13]


The ATR 72 ASW integrates the ATR 42 MP (Maritime Patrol) mission system with the same on-board equipment but with additional ASW capabilities. An anti-submarine warfare (ASW) variant of the −500 (itself a version of the maritime patrol variant of the ATR 42–500) is also in production[14] and has been selected by Turkish Navy and Italian Navy for ASW and anti-surface warfare (ASuW) duties. Ten aircraft will be delivered to the Turkish Navy beginning in 2010. Italy's order of four aircraft will begin deliveries in 2012. For ASW and ASuW missions, the aircraft will be armed with a pod-mounted machine gun, lightweight aerial torpedoes, anti-surface missiles, and depth charges.[15] They will also be equipped with the AMASCOS (Airborne Maritime Situation and Control System) maritime surveillance system of Thales, as well as electronic warfare and reconnaissance systems, and will also be used for maritime search and rescue operations.[16]


A VIP version of the −500 is available with a luxury interior for executive or corporate transport.[17]

ATR 82

During the mid-1980s, the company investigated a 78 seat derivative of the ATR 72. This would have been powered by two Allison AE2100 turboprops (turbofans were also studied for a time) and would have had a cruising speed as high as 330kt. The ATR-82 project (as it was dubbed) was suspended when AI(R) was formed in early 1996.[18]

ATR Quick Change

This version was proposed in order to meet the increasing worldwide demand of cargo and express mail markets,where the aim is to allow operators to supplement their passengers flights with freighter flights.

In Quick Change configuration,the smoke detector is equipped alongside other modifications required in order to meet the certification for full freight operations.The aircraft was equipped with substantially large cargo door at 1.27 m (50 in) in width and 1.52 m (60 in) height,and the containerized freight loading is made easy by the low door sill height located on an average 1.2 m (4 ft).

It takes 30 minutes to convert the aircraft on ATR 42,while for ATR 72, it takes 45 minutes for the same tasks. Each optimized container has 2.8m3 (99 cu.ft)of usable volume and maximum payload is 435 kg (960 lb).[19]
Specifications (ATR 72 500)(ATR 72 600)
ATR 72 500/600
Crew 2
Capacity 70 to 78 passangers
Length 27.17 m (89 ft 2 in)
Wingspan 27.05 m (88 ft 9 in)
Height 7.65 m (25 ft 1 in)
Wing area 61.00 m2 (656.6 sq ft)
Aspect ratio 12.0:1
Empty weight 12,950 kg (28,550 lb)
Max takeoff weight 22,500 kg (49,604 lb)
Powerplant 2 × Pratt & Whitney Canada PW127F turboprops, 1,846 kW (2,475 shp) each
Typical cruise speed 276 knots (511 km/h)
Maximum Cruise speed 344 mph (554 km/h) 299 knots
Range 1,330 km
Service ceiling 7,620 m (25,000 ft)
Takeoff Run at MTOW 1,165 m (3,822 ft)
Boeing’s small diameter bomb

The US Navy has awarded a firm-fixed-price contract to Boeing to develop and deliver high altitude anti-submarine warfare weapon capabilities (HAAWC), designed to target submarines.

Under the $19.2m cost-plus-fixed-fee, cost-plus-incentive-fee, cost-fixed-price-incentive, contract, Boeing will develop the precision-guided HAAWC glide weapon using smart bomb technology to serve as an anti-submarine weapon.

The company will also design HAAWC air launch accessory (ALA) assets and equipment, in addition to associated engineering services and support.

Boeing weapons and missile systems vice-president James Dodd said: "The capability HAAWC gives US Navy sub-hunters is unparalleled compared with what is available today."

The glide weapon development will adapt technologies from Boeing's Joint Direct Attack Munition (JDAM) and Small Diameter Bomb (SMD) for launch from high altitudes and at great distance from targets, to reduce development risk and cost for the navy.
“The capability HAAWC gives US Navy sub-hunters is unparalleled compared with what is available today."

Boeing Direct Attack Weapons director Scott Wuesthoff said, "Providing this advanced capability to Navy warfighters as soon as possible is vital to help protect the United States' maritime interests around the world."

Designed for internal and external carriage, the SDB system is the next-generation of low-cost and low collateral-damage precision strike weapons.

Used with Mk-83/BLU-110, Mk-84, BLU-109 and Mk-82 warheads, the JDAM is capable of updating its trajectory all through its flight to strike the target through its navigation system.

The contract is valued at $47m including options, and the US Naval Sea Systems Command will serve as the contracting activity.

Scheduled to be complete by April 2016, work under the contract will be carried out in St Charles, Missouri, US.

Air ASW efforts began in earnest during World War II to counter the dangerous submarine threat. The devastation and terror experienced earlier during World War I dramatically prioritized the requirement for effective ASW forces; including aircraft. The duelists, the aircraft and the submarine, have been locked into an intense chess match ever since World War II. With each new tactical or technological innovation for Air ASW, the submarine threat counters with either a new procedure or system. The three distinct historic phases of Air ASW include the World War II years, the Cold War period, and the Post-Cold War era.
World War II Years
Aircraft in the early days of Air ASW primarily relied upon visual lookouts to detect submarines. These patrolling aircraft consisted mainly of Consolidated PBY-5 Catalina seaplanes, smaller aircraft, and various airships (or blimps). Their weapon systems were limited to guns, depth bombs, and rockets.

Of course, having offensive weapons did not necessarily ensure aircraft survivability. In June 1943, Airship K-74 on a night patrol off the Florida coast attacked a surfaced German submarine. The airship was shot down in the ensuing gun duel. The submarine, U-134, was forced to return to base. As the submarine struggled back home, it survived two subsequent attacks but was finally sunk by British bombers in the Bay of Biscay.

In the European theater, ASW aircraft patrolled from airfields in Iceland and French Morocco as well as various European airstrips. Coverage of the North Atlantic came from Argentia located in Newfoundland, Canada while patrols from Natal, Brazil watched the South Atlantic. Aircraft operated from many sites within the continental U.S. as well as Puerto Rico, Cuba, Trinidad, and Panama to cover the Caribbean and the Gulf of Mexico.

The Japanese submarine threat was countered by aircrews operating from Australia and the many islands of the South Pacific, Hawaii, and the Aleutians. Protection of the West Coast was provided mainly from airfields in San Diego and Moffett Field, California. Interestingly enough, seaplanes operating from distant bases were periodically refueled at sea by submarines designed to deliver aviation gasoline.

World War II-vintage diesel submarines still had to surface during the night to re-charge their spent batteries. ASW aircraft countered these submarine nighttime operations with searchlights, flares and radar systems. This worked for a while until the submarine community responded with electro-magnetic sensors to detect aircraft radar emissions, snorkels to minimize their exposed hull surfaces, and radar decoys. Other ASW aircraft sensors employed during World War II included MAD and sonobuoys. Additionally, aircraft went through many different paint camouflage schemes to mask their appearance not only from hostile submarines, but also from enemy aircraft, ships, and coastal land watch.

Prior to the attack on Pearl Harbor, Catalina aircraft began experimentation with Magnetic Anomaly Detection (MAD) systems. A Catalina operating from Quonset Point, Rhode Island successfully demonstrated the MAD system by detecting a submarine during the initial testing. Additionally, ten days after the Pearl Harbor attack, the Naval Research Laboratory (NRL) satisfactorily demonstrated a duplex switch which allowed a Catalina radar system to transmit and receive electromagnetic pulses without using a cumbersome secondary antenna system.

Although sonobuoys had been developed in 1941, the concept was not fully endorsed. Meanwhile, blimps were wasting time and weapons after detecting multiple MADs of sunken ships and old wrecks. They needed a sensor to validate and corroborate MAD contacts. Hence the passive sonobuoy concept was "dusted off" the shelves for use by the airships. In February 1942, the Navy's Coordinator for Research and Development requested the National Defense Research Committee (NDRC) to develop an expendable radio sonobuoy which could be used by lighter-than-air (LTA) aircraft.

In March 1942, the practicality of sonobuoys was demonstrated off New London, Connecticut as a K-5 blimp detected the propeller sounds of the submarine S-20 at maximum distances of three miles. Radio reception of the signals, however, was limited to five miles. In October 1942, the Bureau of Ships began sonobuoy procurement by purchasing 1,000 sonobuoys and 100 ASW receivers.

Later in June, Project Sail was formally established at Quonset Point for conducting MAD system research and testing. Sponsored by the Naval Ordnance Laboratory and the NDRC, the promising results conducted with airships and an Army B-18 resulted in the procurement of 200 MAD units. The successful deployment of a working MAD system consequently led to the requirement for a weapon system to attack submarines. Detection of MAD signatures occurs after the aircraft has flown over the submarine. Hence, a retro-rocket weapon was designed to fly backwards a short distance to the approximate position where the MAD anomaly was detected and release a depth bomb. These retro-rockets were designed by the California Institute of Technology using a Catalina aircraft. They were installed a year later to complement the MAD gear in VP-63 aircraft. In January 1944, VP-63 aircraft began patrolling the Straits of Gibraltar. The aircraft threat and the associated MAD gear effectively closed submarine daylight transits through this narrow channel. Five weeks later, VP-63 detected the MAD signature of a submarine attempting to cross the straits. Attacked by Catalina retro-rockets, the submarine (U-761) was later sunk with the assistance of two other ships and additional aircraft.

Air ASW efforts were not just limited to improved sensors; improvements in ASW aircrafts were also examined. In June 1942, Igor Sikorsky's VS-300 helicopter was inspected by naval personnel and recommended for ASW and life-saving operations. The following month, the Bureau of Aeronautics issued a Planning Directive calling for the procurement of Sikorsky's helicopters. In April 1943, the Commander-in-Chief of the U.S. Fleet established a joint board to evaluate helicopters for ASW. Later that June, helicopters were recommended to carry radar and dipping sonar systems and to use these primitive helicopters as a hunter platform rather than a killer unit. By January 1944, it was determined that a helicopter with ASW capability would be limited to coastal waters until flight performance improvements could be made.

Meanwhile, in February 1943, a Letter of Intent (LOI) was sent to the Lockheed Vega Airplane Division for the development of two XP2V-1 patrol planes. This would be the initial development of the U.S. Navy's patrol plane workhorse through the early 1960's, the Lockheed P-2V Neptune.

By the end of the war, Navy and Marine aircraft sank 13 submarines. Working with other forces, they sank 26 submarines (6 Japanese, 20 German).
Cold War Period

As the United States entered the Cold War period, Air ASW advancements continued as the Martin SP-5B Marlin seaplane, the Lockheed P-2V Neptune and the Grumann S-2F Tracker aircraft began searching for Soviet submarines. Also, the effectiveness of helicopters with dipping (or dunking) sonars would now be emphasized. Meanwhile, the submarine fleet was getting harder to find. As nuclear submarines began entering the inventory in the mid-1950's and newer diesel submarines were constructed, more advance Air ASW systems would have to be developed. One method of acoustically locating submarines was through the use of "Julie." "Julie" utilized small explosive charges which created an acoustic pulse that was bounced off submarine hulls and detected by passive sonobuoys. Conversely, a passive method to find snorkeling diesel submarines was a system called "sniffer." "Sniffer" operated somewhat similar to today's smoke detectors. It detected minute air particles and contaminants from the operation of a submarine diesel engine. Aircraft would mark their position after each sniffer detection. After several detections and adjusting for the wind, aircrews could begin localizing the snorkeling diesel submarine.

Most of the Air ASW operations were against the quickly growing Soviet submarine fleet. Typical ASW operations included tracking ballistic missile submarines as well as searching for attack and guided missile submarines shadowing the U.S. Fleet. Sonobuoys began to be used quite extensively during this period. Additionally, a lot of research was conducted to determine sound transmission characteristics of the ocean. This would lead to different sonobuoy designs to catalog water temperature profiles, to measure background noise levels, and to distinguish the different natural and manmade sounds.

Initial operating tests of the XCF dunking sonar began in January 1946. The sonar was carried aboard an H02S helicopter flying from Key West, Florida. Meanwhile, production of the Lockheed P-2V Neptune began at the end of World War II. Neptune aircraft production for the U.S. Navy would continue until 1962. During the time period, the Neptune would demonstrating its versatility by setting several endurance records as well as launching from the carrier deck of the U.S.S. Coral Sea using jet-assisted take-off (JATO) bottles.

Anecdotally, the Navy and the Bureau of Standards in late 1953 announced a joint project called "Tinker Toy". They were developing a process for the automated manufacture of electronic equipment and demonstrated its success by assembling a sonobuoy. Through this project, the sonobuoy would become a pivotal ground-breaker for the development of the microelectronic and solid state circuitry manufacturing industry.

In late spring, 1958, the HSS-1N helicopter, capable of both day and night ASW in poor weather conditions was publicly flown. By late summer that same year the Lockheed Electra civilian airliner design, selected as a replacement for the venerable Neptune, would fly its maiden flight as a P3V-1. By mid-March the following year, the HSS-2 amphibian all-weather ASW helicopter would also make its first flight.

The first P-3A was produced on April 15, 1961. It would later be followed by the P-3B which included more powerful engines and improved ASW acoustic sensors. In May 1969, the P-3C Orion aircraft was unveiled. As the P-3 Orion aircraft continued to enter the Fleet, older ASW aircraft began to be phased out. For example, the SP-5B Marlin of VP-40 completed the last U.S. Navy seaplane flight in October 1967. Additionally, the Navy Air Systems Command initiated a contract with Lockheed in August 1969 to develop the S-3 Viking to replace the aging Grumann S-2 Tracker.

The beginning years of the next decade saw many changes in Air ASW platforms. In July 1970, the P-3C Orion began its first operational deployment from Keflavik, Iceland. The advancements of the P-3C included the processing of directional sonobuoys as well as an onboard computer system. On October 1972, the SH-2D LAMPS Mk I helicopter was accepted for Fleet usage.

In November 1971, the first S-3A was completed by Lockheed. In January 1972, the S-3A completed its inaugural flight. The S-3A Viking would double the speed and range of its predecessor as well as tripling the search area capability. It began acceptance trials in October 1973 and was officially introduced into the Fleet in February 1974.

Also in 1974, a Harpoon air-to-surface missile was first launched by a P-3 Orion. This would lead to an expanded role for the versatile land-based aircraft. During the fall, a prototype LAMPS Mk III H-2/SR helicopter was delivered to the Kaman Aerospace Corporation for flight certification. The following year, in 1975, the first production P-3C Update I aircraft was delivered to VX-1. It included upgrades in navigation by the addition of the OMEGA system, better acoustic processors, a tactical display scope, and a seven-fold increase in computer memory. That same year saw the end of an era as the last S-2 Tracker was withdrawn from service after 22 years of operation.

On August 29, 1977, the first P-3C Update II arrived at the Naval Air Test Center for technical evaluation. It included an Infra-Red Detection System (IRDS) and was outfitted for the Harpoon air-to-surface missile. The first launch of a Harpoon missile by an operational squadron occurred in July 1979. Earlier in September 1978, the P-3C Update III test platform was delivered. The P-3C Update III would include an advance signal processor to replace the aging AN/AQA-7 acoustic processors. Additionally, the last P-2V Neptune rolled off the production line heading for Japan.

Meanwhile a new ASW helicopter, the LAMPS Mk III built by Sikorsky, was selected by the Navy on September 1, 1977. The following February, the Department of Defense authorized full scale development of the LAMPS Mk III. The SH-60B Seahawk LAMPS Mk III mock-up was put through shipboard compatibility trial during the summer of 1978. The following year, Sikorsky unveiled the SH-60B. The LAMPS Mk III would greatly expand and augment the ASW and anti-surface warfare (ASUW) role played by the destroyers and cruisers.

In 1982, the terror of the submarine threat was re-emphasized as an old Argentine submarine built during World War II successfully evaded determined and well-equipped British ASW forces during the Falkland Islands War. The Argentine submarine-launched torpedo attacks were unsuccessful due to the antiquity of the 1940's vintage weapons. Conversely, the threat posed by British submarines and aircraft severely restricted the Argentine Navy to the safety of the South American coast. From either perspective, the submarine threat and the ASW capabilities of each fleet were primary factors in the final outcome.

In 1985, the improved version of the Viking, the S-3B, was flown. It would include extensively improved acoustic and non-acoustic sensors as well as outfitting for the Harpoon missile. By the late 1980's, the SH-60F was developed to begin replacing the aging SH-3 helicopter. The SH-60F included an improved dipping sonar system and coupled it to the airframe of the successful SH-60B LAMPS Mk III helicopter. The SH-60F helicopter would provide inner zone protection of carrier battle groups. Additionally, a standardized helicopter airframe for both LAMPS and inner zone protection missions yields significant logistical savings.
Post-Cold War Era

Post-Cold War ASW operations continued….however with a new submarine threat. Many Third World nations began purchasing some of the latest designs in diesel submarine technology. Rapid advances in battery technology and alternate energy producing systems have extended the submerged endurance of a diesel submarine operating on batteries. Additionally, new designs and materials have been used to quiet noisy submarine sources as well as defeat active sonar systems. Also, these newer submarines now operate in the much noiser and difficult shallow waters along the coast (littoral waters). These modernized diesel submarines can be used to insert military personnel, lay deadly minefields, launch devastating cruise and guided missile, threaten vital shipping lanes, and of course, attack ships and submarines.

Passive acoustic detection of these increasingly quiet submarines has been limited and forced Air ASW aircrews to counter with improved active sonar systems as we enter the 21st century. Nevertheless, the Air ASW challenges ahead continue to be met by the US Navy's frontline ASW aircraft; the P-3C Updates II and III, the S-3B, the SH-60B/F and the SH-2G.
ASW Sensors
Sensors Detecting the stealthy submarine starts with maintaining a tool kit of different sensors. Each sensor has specific applications that counters different submarine operations. Many of these sensors complement and corroborate each other to enhance ASW effectiveness. Air ASW sensors are divided into two basic types; acoustic and non-acoustic. In some foreign services, these acoustic and non-acoustic sensors are commonly referred to as wet- and dry-end sensors,

Non-acoustic sensors augment the detection capability provided by acoustic sensors. These sensors use radar to detect exposed periscopes and hull surfaces, electro-magnetic systems to intercept the radar emissions from submarines, infra-red receivers to detect the heat signatures of surfaced submarines, or Magnetic Anomaly Detectors (MAD) to sense small changes in the Earth's magnetic field caused by the passage of a submarine. This sophisticated technology is further enhanced by vigilant lookouts who are carefully scanning the turbulent ocean surface for submarine periscopes and wakes.
Radar Sensors
Radar sensors have been used since World War II for the detection of surfaced or snorkeling submarines. Back then, submarines relied upon their batteries for submerged operations. Eventually their batteries would become drained to the point where they were forced to return to the surface and operate their diesel engines to re-charge the battery. While surfaced, the submarine was extremely vulnerable to detection by both radar and visual sensors. The addition of a snorkel enabled the submarine to operate its battery-charging diesel engines while minimizing its exposure to radar and visual sensors. Additionally, the background clutter of the surrounding ocean waves limited radar and visual detection. Also, the development of submarine-based electro-magnetic sensors provided the submarine commander with suffficient warning to dive if approaching radar emissions were detected.

Eventually, nuclear submarines where developed which eliminated the need to periodically recharge the batteries. Despite this significant advance, not all nations were able to build nuclear submarines due to financial and technological reasons. Those nations which remain committed to diesel power have pursued technology which limits the number of times the submarine has to recharge its batteries. However, many submarine commanders must still use their periscopes to provide final visual classification of targets prior to attack. Because of this requirement for target verification, radar systems are still used to detect submarine periscopes.

Today's airborne radar systems must be lightweight yet sufficiently capable for ASW operations, long-range detection and surveillance of surface vessels, airborne navigation, and weather avoidance. For that purpose, many Air ASW radar systems use different radar frequencies, scanning speeds, transmission characteristics, pulse lengths, and signal processing methods that reduce background sea clutter and enhance radar returns from exposed pericopes and submarine hulls. The hostile submarine using electro-magnetic sensors, however, can still detect ASW aircraft radar emissions at a much greater distance than the aircraft can detect the submarine by radar. Nevertheless, the threat of radar detection is sufficient to keep the submarine submerged. Radar systems now used aboard U.S. Navy ASW aircraft include the AN/APS-115 (P-3C), AN/APS-124 (SH-60B), and AN/APS-137 (S-3B, some P-3Cs).
Magnetic Anomaly Detection (MAD) Sensors
MAD sensors are used to detect the natural and manmade differences in the Earth's magnetic fields. Some of these differences are caused by the Earth's geological structures and sunspot activity. Other changes can be caused by the passing of large ferrous objects, such as ships, submarines or even aircraft through the Earth's magnetic field. MAD sensor operation is similar in principle to the metal detector used by a treasure hunter or the devices used by utility companies to find underground pipes.

For ASW purposes, the ASW aircraft must almost be essentially overhead or very near the submarine's position to detect the change or anomaly. The detection range is normally related to the distance between the aircraft sensor ("MAD head") and the submarine. Naturally, the size of the submarine and its hull material composition normally determines the strength of the anomaly. Additionally, the direction travelled by both the aircraft and the submarine relative to the Earth's magnetic field is also a factor. Nevertheless, the close proximity required for magnetic anomaly detection makes the MAD system an excellent sensor for pinpointing a submarine's position prior to an air-launched torpedo attack.

In order to detect an anomaly, the MAD head of the aircraft tries to align itself with the noise produced by the Earth's magnetic field. Through this alignment, the noise appears as a near-constant background noise value which enables the operator to recognize any contrasting submarine magnetic anomalies from the background noise. However, any rapid changes in aircraft direction or the operation of certain electronic equipment and electric motors can produce so much aircraft electro-magnetic noise that makes the detection of the submarine's magnetic signature virtually impossible. Special electronic circuitry is enabled to compensate and null out this aircraft magnetic noise. Additionally, the MAD head is placed the farthest distance away from all the interfering sources. That is why the P-3C Orion aircraft has its distinct tail stinger or "MAD boom". On the S-3B, a similar MAD boom is installed and is electrically extended away from the aircraft during MAD operations. Additionally, the SH-60B extends a towed device called a "MAD bird" to reduce aircraft magnetic noise. With continuing advances in both compensation and sensor technology, the detection ranges for MAD sensors may be enhanced for the search and localization phases of ASW missions. Currently all naval ASW aircraft use variations of the AN/ASQ-81 MAD system. A few P-3C aircraft use an advance MAD system, the AN/ASQ-208, that uses digital processing.
Electro-Magnetic (EM) Sensors
Electro-Magnetic (EM) sensors passively scan the radio frequency spectrum for intentional electronic transmissions from hostile forces. These electronic emissions originate from land sites, ships, and aircraft. They can also be detected from submarines. By comparison, Air ASW EM sensors are sophisticated versions of radar detectors used to sense police radar gun signals. The difference, of course, is that Air ASW EM sensors provide all the details necessary to classify and localize the type of electro-magnetic emission that has been detected.

Since the radio-frequency spectrum is extremely cluttered with both hostile, friendly, and neutral electronic emissions, ASW aircraft EM systems are designed to search mainly for radar signals. To further reduce the electronic clutter, signature libraries are used to selectively search for specific submarine radar signals while disregarding signals from friendly and neutral radar systems. Detection of electronic emissions, however, is dependent upon the submarine commander's gamble to operate the submarine radar. Although, EM systems are not normally one of the primary ASW sensors, its flexibility for detecting hostile aircraft and naval combatants at long ranges makes it an effective sensor for all air warfare missions. Its potential presence deters the operation of submarine radar systems forcing the submarine commander to rely on other less accurate sensors to find targets. EM systems installed on naval ASW aircraft include the AN/ALQ-78 and AN/ALR-66 series on the P-3C Orion, the AN/ALQ-142 on the SH-60B Seahawk, and the AN/ALR-76 on the S-3B Viking.
Infra-Red (IR) Sensors
IRsensors are used to detect the heat signatures that extend beyond the visible light spectrum. They are commonly called either FLIR (Forward Looking Infra-Red) or IRDS (Infra-Red Detection System). The major difference between FLIR and IRDS is that FLIR passively scans for IR sources forward of the aircraft whereas IRDS searches all around the aircraft. This passive sensor device must be cryogenically cooled in order to detect IR sources. The IR signature itself can be masked by warm waters and high humidity. When conditions permit, medium detection ranges can be obtained that are comparable or even better than normal visual search ranges. At night, the system works even better as long as there is a noticeable difference in temperature between the source and the background environment. IR systems for nighttime ASW operations have replaced the previous method of illuminating the ocean with either a searchlight or flares; active visual search methods. By using a passive system such as either FLIR or IRDS, the submarine commander has another dilemma to solve on whether to snorkel or surface during the night. Most ASW aircraft utilize the IR sensors not only for ASW, but also for maritime surveillance.
Visual Sensors

Many submarine contacts are still detected using visual scanning techniques. These techniques are sometimes augmented by sophisticated binocular and other electro-optical devices. Submarine commanders are still wary of being visually spotted and maintain a safe speed when their periscopes are exposed so that their telltale wake remains indistinct compared to the background sea clutter. The position of the Sun and the Moon as well as the direction of the ocean waves are all factors the submarine commander must consider in order to remain unobserved. In some regions of the world, phosphorescent marine organisms illuminate a submerged submarine allowing it to be visually spotted. Additionally, some aircrews may use night vision goggles to aid in visual detection at night.

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