Final report Qantas Flight 72

1 final report

1.1 analysis
1.2 potential trigger types
1.3 conclusion
1.4 subsequent qantas flight 71 incident

final report
analysis

after detailed forensic analysis of fdr data, flight control primary computer (fcpc) software , air data inertial reference unit (adiru), determined cpu of adiru corrupted angle of attack (aoa) data. exact nature adiru cpu erroneously relabelled altitude data word binary data represented 37,012 (the altitude @ time of incident) represent angle of attack of 50.625 degrees. fcpc processed erroneously high aoa data, triggering high-aoa protection mode, sent command electrical flight control system (efcs) pitch nose down.

potential trigger types

a number of potential trigger types investigated, including software bugs, software corruption, hardware faults, electromagnetic interference , secondary high energy particles generated cosmic rays. although definitive conclusion not reached, there sufficient information multiple sources conclude of potential triggers unlikely have been involved. more scenario marginal hardware weakness of form made units susceptible effects of type of environmental factor, triggered failure mode.

the atsb assessment of speculation possible interference naval communication station harold e. holt or passenger personal electronic devices have been involved extremely unlikely .

conclusion

the atsb s final report issued on 19 december 2011 concluded incident occurred due combination of design limitation in flight control primary computer (fcpc) software of airbus a330/airbus a340, , failure mode affecting 1 of aircraft s 3 air data inertial reference units (adirus). design limitation meant that, in rare , specific situation, multiple spikes in angle of attack (aoa) data 1 of adirus result in fcpcs commanding aircraft pitch down.

subsequent qantas flight 71 incident

on 27 december 2008, qantas a330-300 aircraft operating perth singapore involved in occurrence approximately 260 nautical miles (480 km) north-west of perth , 350 nautical miles (650 km) south of learmonth airport @ 1729 wst while flying @ 36,000 feet. @ time, autopilot disconnected , crew received alert indicating problem adiru number 1. crew actioned revised procedure released airbus after earlier accident , returned perth uneventfully. atsb include incident in existing accident investigation.

the incident again fuelled media speculation regarding significance of harold e. holt facility, australian , international pilots association calling commercial aircraft barred area precaution until events better understood, while manager of facility has claimed highly, highly unlikely interference has been caused.