Air Data Inertial Reference Unit

8/12/2019 Air Data Inertial Reference Unit

1/7


2/7

19/6/2014 Air data inertial reference unit - Wikipedia, the free encyclopedia

http://en.wikipedia.org/wiki/Air_data_inertial_reference_unit

An ADIRS consists of up to three fault tolerant ADIRUs located in the aircraft electronic rack, an associated

control and display unit (CDU) in the cockpit and remotely mounted air data modules (ADMs).[6]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 display

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 air data

reference (ADR) fault will cause the loss of airspeed and altitude information on the affected display. In either casethe information can only be restored by selecting the No 3 ADIRU.[1]

Each ADIRU comprises an ADR and an inertial reference (IR) component.[7]

Air data reference

The ADR component of an ADIRU provides airspeed, Mach number, angle of attack, temperature and barometri

altitude data. Ram air pressure and static pressures used in calculating airspeed are measured by small ADMs

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.[4]

Inertial reference

The IR component of an ADIRU gives attitude, flight path vector, ground speed and positional data.[1]The ring

laser gyroscope is a core enabling technology in the system, and is used together with accelerometers, GPS and

other sensors to provide raw data.[8]The primary benefits of a ring laser over older mechanical gyroscopes are tha

there are no moving parts, it is rugged and lightweight, frictionless and does not resist a change in precession.

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 even

of a failure. In the case of Qantas Flight 72, 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 redunda

systems they were relying upon.[9]

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.[1][2][3][9]

Failures and directives

FAA Airworthiness directive 2000-07-27
http://en.wikipedia.org/wiki/Qantas_Flight_72http://en.wikipedia.org/wiki/Precessionhttp://en.wikipedia.org/wiki/Gyroscopehttp://en.wikipedia.org/wiki/GPShttp://en.wikipedia.org/wiki/Accelerometerhttp://en.wikipedia.org/wiki/Ring_laser_gyroscopehttp://en.wikipedia.org/wiki/Inertial_reference_unithttp://en.wikipedia.org/wiki/ARINC_429http://en.wikipedia.org/wiki/Pitot_tubehttp://en.wikipedia.org/wiki/Airspeedhttp://en.wikipedia.org/wiki/Mach_numberhttp://en.wikipedia.org/wiki/EFIS#Primary_flight_display_.28PFD.29http://en.wikipedia.org/wiki/Angle_of_attackhttp://en.wikipedia.org/wiki/Redundancy_(engineering)http://en.wikipedia.org/wiki/Fault-tolerant_design


3/7



On May 3, 2000, the FAA issued airworthiness directive 2000-07-27, addressing dual critical failures during fligh

attributed to power supply issues affecting early Honeywell HG2030 and HG2050 ADIRU ring laser gyros used o

several Boeing 737, 757, Airbus A319, A320, A321, A330, and A340 models.[2][10][11]

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 airspeedata.[2][12]

Alitalia A-320

On 25 June 2005, an Alitalia 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.[13]

Malaysia Airlines Flight 124

On 1 August 2005 a serious incident involving Malaysia Airlines 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.[14]In that incident the incorrect data impacted all planes of

movement while the aircraft was climbing through 38,000 feet (11,600 m). The aircraft pitched up and climbed to

around 41,000 feet (12,500 m), with the stall warning activated. The pilots recovered the aircraft with the autopilo

disengaged and requested a return to Perth. During the return to Perth, both the left and right autopilots were brief

activated by the crew, but in both instances the aircraft pitched down and banked to the right. The aircraft wasflown 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.[15]

The US Federal Aviation Administration issued Emergency Airworthiness Directive (AD) 2005-18-51 requiring a

777 operators to install upgraded software to resolve the error.[16]

Qantas Flight 68

On 12 September 2006, Qantas Flight 68, Airbus A330 registration VH-QPA, from Hong Kong to Perth

exhibited ADIRU problems but without causing any disruption to the flight. At 41,000 feet (12,000 m) and

estimated position 530 nautical miles (980 km) north of Learmonth, Western Australia, [17]NAV IR1 FAULTthen

30 minutes later,NAV ADR 1 FAULTnotifications 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
http://en.wikipedia.org/wiki/Inertial_Reference_Unithttp://en.wikipedia.org/wiki/Electronic_Centralised_Aircraft_Monitorhttp://en.wikipedia.org/wiki/Learmonth,_Western_Australiahttp://en.wikipedia.org/wiki/Perth,_Western_Australiahttp://en.wikipedia.org/wiki/Hong_Konghttp://en.wikipedia.org/wiki/Airbus_A330http://en.wikipedia.org/wiki/Qantashttp://en.wikipedia.org/wiki/Federal_Aviation_Administrationhttp://en.wikipedia.org/wiki/Accelerometerhttp://en.wikipedia.org/wiki/Flight_dynamicshttp://en.wikipedia.org/wiki/Kuala_Lumpur_International_Airporthttp://en.wikipedia.org/wiki/Perth_Airporthttp://en.wikipedia.org/wiki/Boeing_777http://en.wikipedia.org/wiki/Malaysia_Airlineshttp://en.wikipedia.org/wiki/Pan-panhttp://en.wikipedia.org/wiki/London_Heathrow_Airporthttp://en.wikipedia.org/wiki/Minimum_Equipment_Listhttp://en.wikipedia.org/wiki/Milanhttp://en.wikipedia.org/wiki/Airbus_A320-200http://en.wikipedia.org/wiki/Alitaliahttp://en.wikipedia.org/wiki/Ring_laser_gyrohttp://en.wikipedia.org/wiki/Honeywell


4/7



and intermittentADR 1 FAULTlight 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.[1

Jetstar Flight 7

On 7 February 2008, a similar aircraft (VH-EBC) operated by Qantas subsidiary Jetstar Airways was involved in

similar occurrence while conducting the JQ7 service from Sydney to Ho Chi Minh City, Vietnam. In this event -which occurred 1,760 nautical miles (3,260 km) 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.[17]

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.[18]

The ATSB has yet to confirm if this event is related to the other Airbus A330 ADIRU occurrences.[17]

Qantas Flight 72

On 7 October 2008, Qantas Flight 72, 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 tomake 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.[19][20]

Qantas Flight 71

On 27 December 2008, Qantas Flight 71 from Perth to Singapore, the same A330-300 registration VH-QPA an

the same ADIRU as involved in the Qantas Flight 68 incident, was involved in an incident at 36,000 feet

approximately 260 nautical miles (480 km) north-west of Perth and 350 nautical miles (650 km) south of

Learmonth Airport at 1729 WST. The autopilot disconnected and the crew received an alert indicating a problem

with ADIRU Number 1.[21]

Emergency Airworthiness Directive No 2009-0012-E

On 15 January 2009, the European Aviation Safety Agency issued Emergency Airworthiness Directive No 2009-

0012-E (http://ad.easa.europa.eu/ad/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
http://ad.easa.europa.eu/ad/2009-0012-Ehttp://en.wikipedia.org/wiki/European_Aviation_Safety_Agencyhttp://en.wikipedia.org/wiki/RAAF_Learmonthhttp://en.wikipedia.org/wiki/Northrop_Grummanhttp://en.wikipedia.org/wiki/Flight_dynamicshttp://en.wikipedia.org/wiki/Qantas_Flight_72http://en.wikipedia.org/wiki/Jetstar_Airways


5/7


6/7



Healing Avionics Applications: Redundancy Considered Harmful"

(http://www.dcs.gla.ac.uk/~johnson/papers/ISSC09/ADIRU_Accident_Submission.pdf). Retrieved 8 June 2009.

10. ^"Various transport category airplanes equipped with certain Honeywell Air Data Inertial Reference Units"

(http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/WebSearchDefault?

SearchView&Query=AD%202000-07-

27&SearchOrder=1&SearchMax=0&SearchWV=TRUE&SearchFuzzy=FALSE&Start=1&Count=100#). US

Federal Aviation Authority. April 18, 2000. Retrieved 2008-10-15.

11. ^"AD/INST/45 Honeywell Air Data Inertial Reference Units 6/2000 DM"

(http://www.casa.gov.au/airworth/airwd/ADfiles/equip/inst/INST-045.pdf). Australian Civil Aviation Safety

Authority. April 27, 2000.

12. ^"Airbus model A318, A319, A320, and A321 series airplanes equipped with certain Northrop Grumman (former

Litton) Air Data Inertial Reference Units"

(http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/WebSearchDefault?

SearchView&Query=AD%202003-26-

03&SearchOrder=1&SearchMax=0&SearchWV=TRUE&SearchFuzzy=FALSE&Start=1&Count=100#). US

Federal Aviation Authority. August 6, 2008. Retrieved 2008-10-15.13. ^"AAIB Bulletin: 6/2006" (http://www.aaib.dft.gov.uk/cms_resources/Airbus%20A320-200,%20I-BIKE%2006-

06.pdf) (PDF). UK Air Accidents Investigation Branch. 2006. Retrieved 2008-10-15.

14. ^Accident description for Malaysia Airlines Flight 124 (http://aviation-safety.net/database/record.php?

id=20050801-1) at the Aviation Safety Network. Retrieved on 2008-10-15.

15. ^"In-flight upset event, 240 km north-west of Perth, WA, Boeing Company 777-200, 9M-MRG, 1 August 2005"

(http://www.atsb.gov.au/publications/investigation_reports/2005/AAIR/pdf/aair200503722_001.pdf) (PDF).

Australian Transport Safety Bureau. 2007-03-13. Retrieved 2008-10-15.

16. ^"Emergency Airworthiness Directive (AD) 2005-18-51"

(http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgAD.nsf/0/25F9233FE09B613F8625706C005D0C53?

OpenDocument#). Federal Aviation Administration. 2005-08-29. Retrieved 2008-10-15.

17. ^ abcde"In-flight upset, 154 km west of Learmonth, WA, 7 October 2008, VH-QPA, Airbus A330-303 - Interim

Factual" (http://www.atsb.gov.au/publications/investigation_reports/2008/AAIR/pdf/AO2008070_interim.pdf)

(PDF).Aviation Occurrence Investigation AO-2008-070. Australian Transport Safety Bureau. 2009-03-06.

Retrieved 2009-03-07.

18. ^"AD2008-17-12 Airbus" (http://content.atp.com/ADs/pdf/081712.pdf?JServSessionIdroot=d7d0g7xvd1.JS1).

US Federal Aviation Authority. 6 August 2008. Retrieved 2008-10-16.

19. ^"Computer error behind Qantas midair drama" (http://www.abc.net.au/news/stories/2008/10/14/2391134.htm).

Australian Broadcasting Corporation. 14 October 2008. Archived

(http://web.archive.org/web/20081016061452/http://www.abc.net.au/news/stories/2008/10/14/2391134.htm) fro

the original on 16 October 2008. Retrieved 2008-10-15.

20. ^Steve Creedy (17 October 2008). "US tests on false data sent on Qantas jet over WA"

(http://www.theaustralian.news.com.au/business/story/0,28124,24506830-36418,00.html). The Australian.

21. ^"Qantas Airbus A330 incident, 480km North West of Perth on 27 December 2008"

(http://www.atsb.gov.au/newsroom/2009/release/2009_01.aspx) (Press release). Australian Transport Safety

Bureau. 2 January 2009. Archived
http://web.archive.org/web/20090110000406/http://www.atsb.gov.au/newsroom/2009/release/2009_01.aspxhttp://www.dcs.gla.ac.uk/~johnson/papers/ISSC09/ADIRU_Accident_Submission.pdfhttp://www.dcs.gla.ac.uk/~johnson/papers/ISSC09/ADIRU_Accident_Submission.pdfhttp://web.archive.org/web/20090110000406/http://www.atsb.gov.au/newsroom/2009/release/2009_01.aspxhttp://www.atsb.gov.au/newsroom/2009/release/2009_01.aspxhttp://en.wikipedia.org/wiki/The_Australianhttp://www.theaustralian.news.com.au/business/story/0,28124,24506830-36418,00.htmlhttp://web.archive.org/web/20081016061452/http://www.abc.net.au/news/stories/2008/10/14/2391134.htmhttp://en.wikipedia.org/wiki/Australian_Broadcasting_Corporationhttp://www.abc.net.au/news/stories/2008/10/14/2391134.htmhttp://en.wikipedia.org/wiki/Federal_Aviation_Authorityhttp://content.atp.com/ADs/pdf/081712.pdf?JServSessionIdroot=d7d0g7xvd1.JS1http://en.wikipedia.org/wiki/Australian_Transport_Safety_Bureauhttp://www.atsb.gov.au/publications/investigation_reports/2008/AAIR/pdf/AO2008070_interim.pdfhttp://en.wikipedia.org/wiki/Federal_Aviation_Administrationhttp://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgAD.nsf/0/25F9233FE09B613F8625706C005D0C53?OpenDocument#http://en.wikipedia.org/wiki/Australian_Transport_Safety_Bureauhttp://www.atsb.gov.au/publications/investigation_reports/2005/AAIR/pdf/aair200503722_001.pdfhttp://en.wikipedia.org/wiki/Aviation_Safety_Networkhttp://aviation-safety.net/database/record.php?id=20050801-1http://en.wikipedia.org/wiki/Air_Accidents_Investigation_Branchhttp://www.aaib.dft.gov.uk/cms_resources/Airbus%20A320-200,%20I-BIKE%2006-06.pdfhttp://en.wikipedia.org/wiki/Federal_Aviation_Authorityhttp://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/WebSearchDefault?SearchView&Query=AD%202003-26-03&SearchOrder=1&SearchMax=0&SearchWV=TRUE&SearchFuzzy=FALSE&Start=1&Count=100#http://en.wikipedia.org/wiki/Civil_Aviation_Safety_Authorityhttp://www.casa.gov.au/airworth/airwd/ADfiles/equip/inst/INST-045.pdfhttp://en.wikipedia.org/wiki/Federal_Aviation_Authorityhttp://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/WebSearchDefault?SearchView&Query=AD%202000-07-27&SearchOrder=1&SearchMax=0&SearchWV=TRUE&SearchFuzzy=FALSE&Start=1&Count=100#http://www.dcs.gla.ac.uk/~johnson/papers/ISSC09/ADIRU_Accident_Submission.pdf


7/7



(http://web.archive.org/web/20090110000406/http://www.atsb.gov.au/newsroom/2009/release/2009_01.aspx)

fromthe original on 10 January 2009. Retrieved 6 January 2009.

22. ^Simon Hradecky (2 June 2009). "Crash: Air France A332 over Atlantic on June 1st 2009, aircraft impacted

ocean" (http://avherald.com/h?article=41a81ef1/0004&opt=0). The Aviation Herald.

23. ^"Air France 447Two A330 airspeed and altitude incidents under NTSB scrutiny"

(http://aviacaonoticias.wordpress.com/2009/06/28/air-france-447-two-a330-airspeed-and-altitude-incidents-under

ntsb-scrutiny/). aviationnewsrelease. 28 June 2009.

24. ^NTSB INVESTIGATING TWO RECENT INCIDENTS INVOLVING POSSIBLE A-330 SPEED AND

ALTITUDE INDICATION ANOMALIES (http://www.ntsb.gov/news/2009/090625a.html). NTSB. Press release

25 June 2009. Retrieved 14 October 2011

25. ^[1](http://www.ntsb.gov/ntsb/GenPDF.asp?id=DCA09IA055&rpt=p) NTSB

26. ^[2](http://www.ntsb.gov/ntsb/GenPDF.asp?id=DCA09IA064&rpt=p) NTSB

Further reading

Dave Carbaugh, Doug Forsythe, Melville McIntyre. "Erroneous flight instrumenent information"(http://www.boeing.com/commercial/aeromagazine/aero_08/erroneous_textonly.html). Aero Magazine.

Boeing. Archived

(http://web.archive.org/web/20080906001423/http://www.boeing.com/commercial/aeromagazine/aero_08

rroneous_textonly.html) from the original on 6 September 2008. Retrieved 2008-10-16.

Melville Duncan W. McIntyre, Boeing (2003-11-25). "US Patent 6654685 - Apparatus and method for

navigation of an aircraft" (http://www.google.com/patents?id=Aw8PAAAAEBAJ&dq=6654685). United

States Patent Office. Retrieved 2008-10-16.

Retrieved from "http://en.wikipedia.org/w/index.php?title=Air_data_inertial_reference_unit&oldid=605549103"

Categories: Aircraft instruments Aerospace engineering Avionics Navigational equipment

Technology systems GPS navigation devices

Thispage was last modified on 24 April 2014 at 02:33.

Textis available under the Creative Commons Attribution-ShareAlike License; additional terms may apply.

By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia is a registered trademark

of the Wikimedia Foundation, Inc., a non-profit organization.
http://web.archive.org/web/20090110000406/http://www.atsb.gov.au/newsroom/2009/release/2009_01.aspxhttp://www.wikimediafoundation.org/http://wikimediafoundation.org/wiki/Privacy_policyhttp://wikimediafoundation.org/wiki/Terms_of_Usehttp://en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_Attribution-ShareAlike_3.0_Unported_Licensehttp://en.wikipedia.org/wiki/Help:Categoryhttp://en.wikipedia.org/w/index.php?title=Air_data_inertial_reference_unit&oldid=605549103http://en.wikipedia.org/wiki/United_States_Patent_Officehttp://www.google.com/patents?id=Aw8PAAAAEBAJ&dq=6654685http://en.wikipedia.org/wiki/Boeinghttp://web.archive.org/web/20080906001423/http://www.boeing.com/commercial/aeromagazine/aero_08/erroneous_textonly.htmlhttp://en.wikipedia.org/wiki/Boeinghttp://www.boeing.com/commercial/aeromagazine/aero_08/erroneous_textonly.htmlhttp://www.ntsb.gov/ntsb/GenPDF.asp?id=DCA09IA064&rpt=phttp://www.ntsb.gov/ntsb/GenPDF.asp?id=DCA09IA055&rpt=phttp://en.wikipedia.org/wiki/NTSBhttp://www.ntsb.gov/news/2009/090625a.htmlhttp://aviacaonoticias.wordpress.com/2009/06/28/air-france-447-two-a330-airspeed-and-altitude-incidents-under-ntsb-scrutiny/http://en.wikipedia.org/wiki/The_Aviation_Heraldhttp://avherald.com/h?article=41a81ef1/0004&opt=0http://web.archive.org/web/20090110000406/http://www.atsb.gov.au/newsroom/2009/release/2009_01.aspxhttp://en.wikipedia.org/wiki/Category:GPS_navigation_deviceshttp://en.wikipedia.org/wiki/Category:Technology_systemshttp://en.wikipedia.org/wiki/Category:Navigational_equipmenthttp://en.wikipedia.org/wiki/Category:Avionicshttp://en.wikipedia.org/wiki/Category:Aerospace_engineeringhttp://en.wikipedia.org/wiki/Category:Aircraft_instruments

Air Data Inertial Reference Unit

Documents

Transcript of Air Data Inertial Reference Unit