Air Data Inertial Reference Unit
Encyclopedia
An Air Data Inertial Reference Unit (ADIRU) is a key component of the integrated Air Data Inertial Reference System (ADIRS), that supplies air data (airspeed
, angle of attack
and altitude) and inertial reference (position and attitude) information to the pilots' Electronic Flight Instrument System
displays as well as other systems on the aircraft such as the engines, autopilot, flight control and landing gear systems. An ADIRU acts as a single, fault tolerant
source of navigational data for both pilots of an aircraft. It may be complemented by a Secondary Attitude Air Data Reference Unit (SAARU), as in the Boeing 777
design.
This device is used on various military aircraft as well as civilian airliners starting with the Airbus A320
and Boeing 777
.
ADIRUs located in the aircraft electronic rack, an associated Control and Display Unit (CDU) in the cockpit and remotely mounted Air Data Modules (ADMs). The No 3 ADIRU is a redundant
unit that may be selected to supply data to either the commander's or the co-pilot's displays in the event of a partial or complete failure of either the No 1 or No 2 ADIRU. There is no cross-channel redundancy between the Nos 1 and 2 ADIRUs, as No 3 ADIRU is the only alternate source of air and inertial reference data. An Inertial Reference (IR) fault in ADIRU No 1 or 2 will cause a loss of attitude
and navigation information on their associated Primary Flight Display (PFD) and Navigation Display (ND) screens. An ADR (Air Data Reference) fault will cause the loss of airspeed and altitude information on the affected display. In either case the information can only be restored by selecting the No 3 ADIRU.
Each ADIRU comprises an Air Data Reference (ADR) and an Inertial Reference (IR) component.
, angle of attack, temperature and barometric altitude data. Ram air pressure and static pressures used in calculating airspeed
are measured by small Air data module
s (ADM) located as close as possible to the respective pitot
and static pressure sensors. The ADMs transmit their pressures to the ADIRUs through ARINC 429
data buses.
component of an ADIRU gives attitude, flight path vector, ground speed and positional data. The ring laser gyroscope
is a core enabling technology in the system, and is used together with accelerometer
s, GPS and other sensors to provide raw data. The primary benefits of a ring laser over older mechanical gyroscope
s are that there are no moving parts, it is rugged and lightweight, frictionless and does not resist a change in precession
.
, the captain switched the source of IR data from ADIRU1 to ADIRU3 following a failure of ADIRU1; however ADIRU1 continued to supply ADR data to the captain's primary flight display. In addition, the master flight control computer (PRIM1) was switched from PRIM1 to PRIM2, then PRIM2 back to PRIM1, thereby creating a situation of uncertainty for the crew who did not know which redundant systems they were relying upon.
Reliance on redundancy of aircraft systems and can also lead to delays in executing needed repairs as airline operators rely on the redundancy to keep the aircraft system working without having to repair faults immediately.
HG2030 and HG2050 ADIRU ring laser gyros used on several Boeing 737, 757, Airbus A319, A320, A321, A330, and A340 models.
Airbus A320-200 registered as I-BIKE departed Milan
with a defective ADIRU as permitted by the Minimum Equipment List
. While approaching London Heathrow Airport
during deteriorating weather another ADIRU failed, leaving only one operable. In the subsequent confusion the third was inadvertently reset, losing its reference heading and disabling several automatic functions. The crew was able to effect a safe landing after declaring a Pan-pan
.
Flight 124, occurred when a Boeing 777-2H6ER
(9M-MRG) flying from Perth
to Kuala Lumpur
also involved an ADIRU fault resulting in uncommanded manoeuvres by the aircraft acting on false indications. In that incident the incorrect data impacted all planes of movement
while the aircraft was climbing through 38000 feet (11,582.4 m). The aircraft pitched up and climbed to around 41000 feet (12,496.8 m), with the stall warning activated. The pilots recovered the aircraft with the autopilot disengaged and requested a return to Perth. During the return to Perth, both the left and right autopilots were briefly activated by the crew, but in both instances the aircraft pitched down and banked to the right. The aircraft was flown manually for the remainder of the flight and landed safely in Perth. There were no injuries and no damage to the aircraft. The ATSB found that the main probable cause of this incident was a latent software error which allowed the ADIRU to use data from a failed accelerometer
.
The US Federal Aviation Administration
issued Emergency Airworthiness Directive (AD) 2005-18-51 requiring all 777 operators to install upgraded software to resolve the error.
Flight 68, Airbus A330
registration VH-QPA, from Hong Kong
to Perth
exhibited ADIRU problems but without causing any disruption to the flight. At 41000 feet (12,496.8 m) and estimated position 530 NM north of Learmonth, Western Australia, NAV IR1 FAULT then, 30 minutes later, NAV ADR 1 FAULT notifications were received on the ECAM identifying navigation system faults in Inertial Reference Unit
1, then in ADR 1 respectively. The crew reported to the later Qantas Flight 72 investigation involving the same airframe and ADIRU that they had received numerous warning and caution messages which changed too quickly to be dealt with. While investigating the problem, the crew noticed a weak and intermittent ADR 1 FAULT light and elected to switch off ADR 1, after which they experienced no further problems. There was no impact on the flight controls throughout the event. The ADIRU manufacturer's recommended maintenance procedures were carried out after the flight and system testing found no further fault.
was involved in a similar occurrence while conducting the JQ7 service from Sydney to Ho Chi Minh City, Vietnam. In this event - which occurred 1760 NM east of Learmonth - many of the same errors occurred in the ADIRU unit. The crew followed the relevant procedure applicable at the time and the flight continued without problems.
The ATSB has yet to confirm if this event is related to the other Airbus A330 ADIRU occurrences.
, an Airbus A330, departed Singapore for Perth. Some time into the flight, while cruising at 37,000 ft, a failure in the No.1 ADIRU led to the autopilot automatically disengaging followed by two sudden uncommanded pitch
down manoeuvres, according to the Australian Transport Safety Bureau (ATSB). The accident injured up to 74 passengers and crew, ranging from minor to serious injuries. The aircraft was able to make an emergency landing without further injuries. The aircraft was equipped with a Northrop Grumman
made ADIRS, which investigators sent to the manufacturer for further testing.
at 1729 WST. The autopilot disconnected and the crew received an alert indicating a problem with ADIRU Number 1.
issued Emergency Airworthiness Directive No 2009-0012-E to address the above A330 and A340 Northrop-Grumman ADIRU problem of incorrectly responding to a defective inertial reference. In the event of a NAV IR fault the directed crew response is now to "select OFF the relevant IR, select OFF the relevant ADR, and then turn the IR rotary mode selector to the OFF position." The effect is to ensure that the faulted IR is powered off so that it no longer can send erroneous data to other systems.
Flight 447
, an Airbus A330 en route from Rio de Janeiro
to Paris
, disappeared over the Atlantic Ocean after transmitting automated messages indicating faults with various equipment, including the ADIRU. While examining possibly related events of weather-related loss of ADIRS, the NTSB decided to investigate two similar cases on cruising A330s. On a 21 May 2009 Miami-Sao Paulo
TAM Flight 8091 registered as PT-MVB, and on a 23 June 2009 Hong Kong
-Tokyo
Northwest Airlines
Flight 8 registered as N805NW each saw sudden loss of airspeed data at cruise altitude and consequent loss of ADIRS control.
Airspeed
Airspeed is the speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: indicated airspeed , calibrated airspeed , true airspeed , equivalent airspeed and density airspeed....
, angle of attack
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...
and altitude) and inertial reference (position and attitude) information to the pilots' Electronic Flight Instrument System
Electronic Flight Instrument System
An electronic flight instrument system is a flight deck instrument display system in which the display technology used is electronic rather than electromechanical. EFIS normally consists of a primary flight display , multi-function display and engine indicating and crew alerting system display...
displays as well as other systems on the aircraft such as the engines, autopilot, flight control and landing gear systems. An ADIRU acts as a single, fault tolerant
Fault-tolerant design
In engineering, fault-tolerant design is a design that enables a system to continue operation, possibly at a reduced level , rather than failing completely, when some part of the system fails...
source of navigational data for both pilots of an aircraft. It may be complemented by a Secondary Attitude Air Data Reference Unit (SAARU), as in the Boeing 777
Boeing 777
The Boeing 777 is a long-range, wide-body twin-engine jet airliner manufactured by Boeing Commercial Airplanes. It is the world's largest twinjet and is commonly referred to as the "Triple Seven". The aircraft has seating for over 300 passengers and has a range from , depending on model...
design.
This device is used on various military aircraft as well as civilian airliners starting with the Airbus A320
Airbus A320
The Airbus A320 family is a family of short- to medium-range, narrow-body, commercial passenger jet airliners manufactured by Airbus Industrie.Airbus was originally a consortium of European aerospace companies, and is now fully owned by EADS. Airbus's name has been Airbus SAS since 2001...
and Boeing 777
Boeing 777
The Boeing 777 is a long-range, wide-body twin-engine jet airliner manufactured by Boeing Commercial Airplanes. It is the world's largest twinjet and is commonly referred to as the "Triple Seven". The aircraft has seating for over 300 passengers and has a range from , depending on model...
.
Description
An ADIRS consists of up to three fault tolerantFault-tolerant design
In engineering, fault-tolerant design is a design that enables a system to continue operation, possibly at a reduced level , rather than failing completely, when some part of the system fails...
ADIRUs located in the aircraft electronic rack, an associated Control and Display Unit (CDU) in the cockpit and remotely mounted Air Data Modules (ADMs). The No 3 ADIRU is a redundant
Redundancy (engineering)
In engineering, redundancy is the duplication of critical components or functions of a system with the intention of increasing reliability of the system, usually in the case of a backup or fail-safe....
unit that may be selected to supply data to either the commander's or the co-pilot's displays in the event of a partial or complete failure of either the No 1 or No 2 ADIRU. There is no cross-channel redundancy between the Nos 1 and 2 ADIRUs, as No 3 ADIRU is the only alternate source of air and inertial reference data. An Inertial Reference (IR) fault in ADIRU No 1 or 2 will cause a loss of attitude
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...
and navigation information on their associated Primary Flight Display (PFD) and Navigation Display (ND) screens. An ADR (Air Data Reference) fault will cause the loss of airspeed and altitude information on the affected display. In either case the information can only be restored by selecting the No 3 ADIRU.
Each ADIRU comprises an Air Data Reference (ADR) and an Inertial Reference (IR) component.
Air Data Reference
The ADR component of an ADIRU provides airspeed, MachMach number
Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...
, angle of attack, temperature and barometric altitude data. Ram air pressure and static pressures used in calculating airspeed
Airspeed
Airspeed is the speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: indicated airspeed , calibrated airspeed , true airspeed , equivalent airspeed and density airspeed....
are measured by small Air data module
Air data module
Air Data Module is a component of the navigation system on fly-by-wire aircraft, such as Airbus A320 or later Airbus. Each unit converts pneumatic information from a Pitot tube or a static port in to numerical information which is sent on a data bus...
s (ADM) located as close as possible to the respective pitot
Pitot tube
A pitot tube is a pressure measurement instrument used to measure fluid flow velocity. The pitot tube was invented by the French engineer Henri Pitot Ulo in the early 18th century and was modified to its modern form in the mid-19th century by French scientist Henry Darcy...
and static pressure sensors. The ADMs transmit their pressures to the ADIRUs through ARINC 429
ARINC 429
ARINC 429 is the technical standard for the predominant avionics data bus used on most higher-end commercial and transport aircraft. It defines the physical and electrical interfaces of a two-wire data bus and a data protocol to support an aircraft's avionics local area network.-Messages:ARINC 429...
data buses.
Inertial Reference
The IRInertial Reference Unit
An inertial reference unit is a type of inertial sensor which uses gyroscopes and accelerometers to determine a moving aircraft’s or spacecraft’s change in rotational attitude and translational position over a...
component of an ADIRU gives attitude, flight path vector, ground speed and positional data. The ring laser gyroscope
Ring laser gyroscope
A ring laser gyroscope consists of a ring laser having two counter-propagating modes over the same path in order to detect rotation. It operates on the principle of the Sagnac effect which shifts the nulls of the internal standing wave pattern in response to angular rotation...
is a core enabling technology in the system, and is used together with accelerometer
Accelerometer
An accelerometer is a device that measures proper acceleration, also called the four-acceleration. This is not necessarily the same as the coordinate acceleration , but is rather the type of acceleration associated with the phenomenon of weight experienced by a test mass that resides in the frame...
s, GPS and other sensors to provide raw data. The primary benefits of a ring laser over older mechanical gyroscope
Gyroscope
A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...
s are that there are no moving parts, it is rugged and lightweight, frictionless and does not resist a change in precession
Precession
Precession is a change in the orientation of the rotation axis of a rotating body. It can be defined as a change in direction of the rotation axis in which the second Euler angle is constant...
.
Complexity in redundancy
Analysis of complex systems is itself so difficult as to be subject to errors in the certification process. Complex interactions between flight computers and ADIRU's can lead to counter-intuitive behaviour for the crew in the event of a failure. In the case of Qantas Flight 72Qantas Flight 72
Qantas Flight 72 was a scheduled flight from Singapore Changi Airport to Perth Airport on 7 October 2008 that made an emergency landing at Learmonth airport near the town of Exmouth, Western Australia following an inflight accident featuring a pair of sudden uncommanded pitch-down manoeuvres that...
, the captain switched the source of IR data from ADIRU1 to ADIRU3 following a failure of ADIRU1; however ADIRU1 continued to supply ADR data to the captain's primary flight display. In addition, the master flight control computer (PRIM1) was switched from PRIM1 to PRIM2, then PRIM2 back to PRIM1, thereby creating a situation of uncertainty for the crew who did not know which redundant systems they were relying upon.
Reliance on redundancy of aircraft systems and can also lead to delays in executing needed repairs as airline operators rely on the redundancy to keep the aircraft system working without having to repair faults immediately.
FAA Airworthiness directive 2000-07-27
On May 3, 2000, the FAA issued airworthiness directive 2000-07-27, addressing dual critical failures during flight, attributed to power supply issues affecting early HoneywellHoneywell
Honeywell International, Inc. is a major conglomerate company that produces a variety of consumer products, engineering services, and aerospace systems for a wide variety of customers, from private consumers to major corporations and governments....
HG2030 and HG2050 ADIRU ring laser gyros used on several Boeing 737, 757, Airbus A319, A320, A321, A330, and A340 models.
Airworthiness directive 2003-26-03
On 27 January 2004 the FAA issued airworthiness directive 2003-26-03 (later superseded by AD 2008-17-12) which called for modification to the mounting of ADIRU3 to prevent failure and loss of critical attitude and airspeed data.Alitalia A-320
On 25 June 2005, an AlitaliaAlitalia
Alitalia - Linee Aeree Italiane S.p.A. , in its later stages known as Alitalia - Linee Aeree Italiane S.p.A. in Extraordinary Administration, was the former Italian flag carrier...
Airbus A320-200 registered as I-BIKE departed Milan
Milan
Milan is the second-largest city in Italy and the capital city of the region of Lombardy and of the province of Milan. The city proper has a population of about 1.3 million, while its urban area, roughly coinciding with its administrative province and the bordering Province of Monza and Brianza ,...
with a defective ADIRU as permitted by the Minimum Equipment List
Minimum equipment list
In aviation, a Master Minimum Equipment List, or MMEL, is a categorized list of systems, instruments and equipment on an aircraft which are not required to be operative for flight. Specific procedures or conditions may be associated with operation with the relevant item inoperative...
. While approaching London Heathrow Airport
London Heathrow Airport
London Heathrow Airport or Heathrow , in the London Borough of Hillingdon, is the busiest airport in the United Kingdom and the third busiest airport in the world in terms of total passenger traffic, handling more international passengers than any other airport around the globe...
during deteriorating weather another ADIRU failed, leaving only one operable. In the subsequent confusion the third was inadvertently reset, losing its reference heading and disabling several automatic functions. The crew was able to effect a safe landing after declaring a Pan-pan
Pan-pan
In radiotelephone communications, a call of three repetitions of pan-pan is used to signify that there is an urgency on board a boat, ship, aircraft or other vehicle but that, for the time being at least, there is no immediate danger to anyone's life or to the vessel itself. This is referred to as...
.
Malaysia Airlines Flight 124
On 1 August 2005 a serious incident involving Malaysia AirlinesMalaysia Airlines
Malaysian Airline System Berhad , DBA Malaysia Airlines , is the government-owned flag carrier of Malaysia. Malaysia Airlines operates flights from its home base, Kuala Lumpur International Airport, and its eastern hub in Kota Kinabalu. It has its headquarters on the grounds of Sultan Abdul Aziz...
Flight 124, occurred when a Boeing 777-2H6ER
Boeing 777
The Boeing 777 is a long-range, wide-body twin-engine jet airliner manufactured by Boeing Commercial Airplanes. It is the world's largest twinjet and is commonly referred to as the "Triple Seven". The aircraft has seating for over 300 passengers and has a range from , depending on model...
(9M-MRG) flying from Perth
Perth Airport
Perth Airport is an Australian domestic and international airport serving Perth, the capital and largest city of Western Australia. The airport itself is located in the suburb of Perth Airport....
to Kuala Lumpur
Kuala Lumpur International Airport
Kuala Lumpur International Airport , or KLIA serves the capital city of Malaysia, Kuala Lumpur, and is one of Southeast Asia's largest airports. It is also Malaysia's main international airport. It is situated in the Sepang district, in the south of the state of Selangor, about from Kuala Lumpur...
also involved an ADIRU fault resulting in uncommanded manoeuvres by the aircraft acting on false indications. In that incident the incorrect data impacted all planes of movement
Flight dynamics
Flight dynamics is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw .Aerospace engineers develop control systems for...
while the aircraft was climbing through 38000 feet (11,582.4 m). The aircraft pitched up and climbed to around 41000 feet (12,496.8 m), with the stall warning activated. The pilots recovered the aircraft with the autopilot disengaged and requested a return to Perth. During the return to Perth, both the left and right autopilots were briefly activated by the crew, but in both instances the aircraft pitched down and banked to the right. The aircraft was flown manually for the remainder of the flight and landed safely in Perth. There were no injuries and no damage to the aircraft. The ATSB found that the main probable cause of this incident was a latent software error which allowed the ADIRU to use data from a failed accelerometer
Accelerometer
An accelerometer is a device that measures proper acceleration, also called the four-acceleration. This is not necessarily the same as the coordinate acceleration , but is rather the type of acceleration associated with the phenomenon of weight experienced by a test mass that resides in the frame...
.
The US Federal Aviation Administration
Federal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...
issued Emergency Airworthiness Directive (AD) 2005-18-51 requiring all 777 operators to install upgraded software to resolve the error.
Qantas Flight 68
On 12 September 2006, QantasQantas
Qantas Airways Limited is the flag carrier of Australia. The name was originally "QANTAS", an initialism for "Queensland and Northern Territory Aerial Services". Nicknamed "The Flying Kangaroo", the airline is based in Sydney, with its main hub at Sydney Airport...
Flight 68, Airbus A330
Airbus A330
The Airbus A330 is a wide-body twin-engine jet airliner made by Airbus, a division of EADS. Versions of the A330 have a range of and can accommodate up to 335 passengers in a two-class layout or carry of cargo....
registration VH-QPA, from Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
to Perth
Perth, Western Australia
Perth is the capital and largest city of the Australian state of Western Australia and the fourth most populous city in Australia. The Perth metropolitan area has an estimated population of almost 1,700,000....
exhibited ADIRU problems but without causing any disruption to the flight. At 41000 feet (12,496.8 m) and estimated position 530 NM north of Learmonth, Western Australia, NAV IR1 FAULT then, 30 minutes later, NAV ADR 1 FAULT notifications were received on the ECAM identifying navigation system faults in Inertial Reference Unit
Inertial Reference Unit
An inertial reference unit is a type of inertial sensor which uses gyroscopes and accelerometers to determine a moving aircraft’s or spacecraft’s change in rotational attitude and translational position over a...
1, then in ADR 1 respectively. The crew reported to the later Qantas Flight 72 investigation involving the same airframe and ADIRU that they had received numerous warning and caution messages which changed too quickly to be dealt with. While investigating the problem, the crew noticed a weak and intermittent ADR 1 FAULT light and elected to switch off ADR 1, after which they experienced no further problems. There was no impact on the flight controls throughout the event. The ADIRU manufacturer's recommended maintenance procedures were carried out after the flight and system testing found no further fault.
Jetstar Flight 7
On 7 February 2008, a similar aircraft (VH-EBC) operated by Qantas subsidiary Jetstar AirwaysJetstar Airways
Jetstar Airways is an Australian low-cost airline headquartered in Melbourne, Australia. It is a subsidiary of Qantas, created in response to the threat posed by low-cost airline Virgin Blue...
was involved in a similar occurrence while conducting the JQ7 service from Sydney to Ho Chi Minh City, Vietnam. In this event - which occurred 1760 NM east of Learmonth - many of the same errors occurred in the ADIRU unit. The crew followed the relevant procedure applicable at the time and the flight continued without problems.
Airworthiness directive 2008-17-12
On 6 August 2008, the FAA issued airworthiness directive 2008-17-12 expanding on the requirements of the earlier AD 2003-26-03 which had been determined to be an insufficient remedy. In some cases it called for replacement of ADIRUs with newer models, but allowed 46 months from October 2008 to implement the directive.The ATSB has yet to confirm if this event is related to the other Airbus A330 ADIRU occurrences.
Qantas Flight 72
On 7 October 2008, Qantas Flight 72Qantas Flight 72
Qantas Flight 72 was a scheduled flight from Singapore Changi Airport to Perth Airport on 7 October 2008 that made an emergency landing at Learmonth airport near the town of Exmouth, Western Australia following an inflight accident featuring a pair of sudden uncommanded pitch-down manoeuvres that...
, an Airbus A330, departed Singapore for Perth. Some time into the flight, while cruising at 37,000 ft, a failure in the No.1 ADIRU led to the autopilot automatically disengaging followed by two sudden uncommanded pitch
Flight dynamics
Flight dynamics is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw .Aerospace engineers develop control systems for...
down manoeuvres, according to the Australian Transport Safety Bureau (ATSB). The accident injured up to 74 passengers and crew, ranging from minor to serious injuries. The aircraft was able to make an emergency landing without further injuries. The aircraft was equipped with a Northrop Grumman
Northrop Grumman
Northrop Grumman Corporation is an American global aerospace and defense technology company formed by the 1994 purchase of Grumman by Northrop. The company was the fourth-largest defense contractor in the world as of 2010, and the largest builder of naval vessels. Northrop Grumman employs over...
made ADIRS, which investigators sent to the manufacturer for further testing.
Qantas Flight 71
On 27 December 2008, Qantas Flight 71 from Perth to Singapore, the same A330-300 registration VH-QPA and the same ADIRU as involved in the Qantas Flight 68 incident, was involved in an incident at 36,000 feet approximately 260 nautical miles (481.5 km) north-west of Perth and 350 nautical miles (648.2 km) south of Learmonth AirportRAAF Learmonth
RAAF Learmonth, also known as Learmonth Airport , is a joint use Royal Australian Air Force base and civil airport. It is located near the town of Exmouth on the north-west coast of Western Australia. As an RAAF base, Learmonth is one of the RAAF's three 'bare bases'...
at 1729 WST. The autopilot disconnected and the crew received an alert indicating a problem with ADIRU Number 1.
Emergency Airworthiness Directive No 2009-0012-E
On 15 January 2009, the European Aviation Safety AgencyEuropean Aviation Safety Agency
The European Aviation Safety Agency is an agency of the European Union with offices in Cologne, Germany, which has been given regulatory and executive tasks in the field of civilian aviation safety. It was created on 15 July 2002, and it reached full functionality in 2008, taking over functions...
issued Emergency Airworthiness Directive No 2009-0012-E to address the above A330 and A340 Northrop-Grumman ADIRU problem of incorrectly responding to a defective inertial reference. In the event of a NAV IR fault the directed crew response is now to "select OFF the relevant IR, select OFF the relevant ADR, and then turn the IR rotary mode selector to the OFF position." The effect is to ensure that the faulted IR is powered off so that it no longer can send erroneous data to other systems.
Air France Flight 447
On 1 June 2009, Air FranceAir France
Air France , stylised as AIRFRANCE, is the French flag carrier headquartered in Tremblay-en-France, , and is one of the world's largest airlines. It is a subsidiary of the Air France-KLM Group and a founding member of the SkyTeam global airline alliance...
Flight 447
Air France Flight 447
Air France Flight 447 was a scheduled airline flight from Rio de Janeiro-Galeão to Paris-Roissy involving an Airbus A330-200 aircraft that crashed into the Atlantic Ocean on 1 June 2009, killing all 216 passengers and 12 aircrew. The investigation is still ongoing, and the cause of the...
, an Airbus A330 en route from Rio de Janeiro
Rio de Janeiro
Rio de Janeiro , commonly referred to simply as Rio, is the capital city of the State of Rio de Janeiro, the second largest city of Brazil, and the third largest metropolitan area and agglomeration in South America, boasting approximately 6.3 million people within the city proper, making it the 6th...
to Paris
Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...
, disappeared over the Atlantic Ocean after transmitting automated messages indicating faults with various equipment, including the ADIRU. While examining possibly related events of weather-related loss of ADIRS, the NTSB decided to investigate two similar cases on cruising A330s. On a 21 May 2009 Miami-Sao Paulo
São Paulo
São Paulo is the largest city in Brazil, the largest city in the southern hemisphere and South America, and the world's seventh largest city by population. The metropolis is anchor to the São Paulo metropolitan area, ranked as the second-most populous metropolitan area in the Americas and among...
TAM Flight 8091 registered as PT-MVB, and on a 23 June 2009 Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
-Tokyo
Tokyo
, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...
Northwest Airlines
Northwest Airlines
Northwest Airlines, Inc. was a major United States airline founded in 1926 and absorbed into Delta Air Lines by a merger approved on October 29, 2008, making Delta the largest airline in the world...
Flight 8 registered as N805NW each saw sudden loss of airspeed data at cruise altitude and consequent loss of ADIRS control.