Edit Accident: A333, en-route, West of Learmonth Australia, 2008 (LOC AW)

Accident Form

When:	JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember
Event Type:	AGC AI AW BS CFIT CS FIRE GND HF LB LOC LOS RE RI WAKE WX
Day/Night:	None Not Recorded Day Night
Flight Conditions:	None Not Recorded VMC IMC On Ground - Low Visibility On Ground - Normal Visibility
One sentence description:	On 7 October 2008, an Airbus A330-300 aircraft experienced multiple system failure indications followed by uncommanded pitch-down events which resulted in serious injuries to passengers and cabin crew.
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Add Aircraft Involved

Aircraft: Operator: Type of Flight: None Not Recorded Private Public Transport (Passenger) Public Transport (Cargo) Public Transport (Non Revenue) Military/State Aerial Work Out of Service Flight Origin: Intended Destination: Actual Destination: Take-off Commenced: None Yes No Flight Airborne: None Yes No Flight Completed: None Yes No Phase of Flight: None Parked Standing Pushback/towing Taxi Take Off Climb Cruise Descent Missed Approach Landing Manoeuvring

Aircraft: Operator: Type of Flight: None Not Recorded Private Public Transport (Passenger) Public Transport (Cargo) Public Transport (Non Revenue) Military/State Aerial Work Out of Service Flight Origin: Intended Destination: Actual Destination: Take-off Commenced: None Yes No Flight Airborne: None Yes No Flight Completed: None Yes No Phase of Flight: None Parked Standing Pushback/towing Taxi Take Off Climb Cruise Descent Missed Approach Landing Manoeuvring

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Origin: Destination:

Origin: Destination:

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Airport: In Vicinity of airport:

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Coordinates: Location: ICAO Region: AFIAPACCARSAMEURMIDNAMNAT ICAO Territory: AGANAYBGBIBKCCTDADBDFDGDIDNDRDTDXEBEDEEEFEGEHEIEKELENEPESEVEYFAFBFCFDFEFGFHFIFJFKFLFMFNFOFPFQFSFTFVFWFXFYFZGAGBGCGEGFGGGLGMGOGQGSGUGVHAHBHCHDHEHFHHHKHLHRHSHTHUKLALBLCLDLELFLGLHLILJLKLLLMLOLPLQLRLSLTLULWLXLYLZMBMDMGMHMKMMMNMPMRMSMTMUMWMYMZNCNFNGNINLNSNTNVNWNZOAOBOEOIOJOKOLOMOOOPOROSOTOYPAPGPHPJPKPLPMPOPPPTPWRCRJRKRORPSASBSCSESFSGSKSLSMSOSPSUSVSYTATBTDTFTGTITJTKTLTNTQTRTTTUTVTXUAUBUDUEUGUHUIUKULUMUNURUSUTUUUWVAVBVCVDVEVGVHVIVLVMVNVOVQVRVTVVVYWAWBWIWMWPWRWSYYPZZKZM

Coordinates: Location: ICAO Region: AFIAPACCARSAMEURMIDNAMNAT ICAO Territory: AGANAYBGBIBKCCTDADBDFDGDIDNDRDTDXEBEDEEEFEGEHEIEKELENEPESEVEYFAFBFCFDFEFGFHFIFJFKFLFMFNFOFPFQFSFTFVFWFXFYFZGAGBGCGEGFGGGLGMGOGQGSGUGVHAHBHCHDHEHFHHHKHLHRHSHTHUKLALBLCLDLELFLGLHLILJLKLLLMLOLPLQLRLSLTLULWLXLYLZMBMDMGMHMKMMMNMPMRMSMTMUMWMYMZNCNFNGNINLNSNTNVNWNZOAOBOEOIOJOKOLOMOOOPOROSOTOYPAPGPHPJPKPLPMPOPPPTPWRCRJRKRORPSASBSCSESFSGSKSLSMSOSPSUSVSYTATBTDTFTGTITJTKTLTNTQTRTTTUTVTXUAUBUDUEUGUHUIUKULUMUNURUSUTUUUWVAVBVCVDVEVGVHVIVLVMVNVOVQVRVTVVVYWAWBWIWMWPWRWSYYPZZKZM

Add General Tags

Tags: ATC Training Flight Crew Training Military use of civil airport Civil use of military airport Approach not stabilised Aircraft-aircraft collision Aircraft-aircraft near miss Extra flight crew (no training) Safety pilot present Non Precision Approach Circling Approach Event reporting non compliant Inadequate Airworthiness Procedures Inadequate Aircraft Operator Procedures Inadequate ATC Procedures Airspace Design Airport Layout Ineffective Regulatory Oversight Root Cause Not Determined Military Fast Jet Formation Foreign Military Aircraft Approach to Wrong Airport Inadequate Airport Procedures

Add AGC Tags

Tags: Call Sign Confusion Loss of Comms Incorrect Readback missed Phraseology Language Clarity Low Fuel Status CPDLC Flight Crew Oxygen Mask Use Take off without clearance Landing without clearance Military Formation Clearance Military/Civil Coordination Provision of Aircraft Performance Data ATC Clearance Cancelled

Add AI Tags

Tags: CA Incursion DA Incursion PA Incursion TSA Incursion GPS VFR Navigation ATC Complicit Aircraft not in contact with Airspace ATC

Add BS Tags

Tags: Large Birds Flocking Birds Significant Airframe Damage Flight Crew Injury Engine damage Coastal Location Migration Engine Ingestion Prior verbal warning

Add CFIT Tags

Tags: Into water Into terrain Into obstruction No Visual Reference Lateral Navigation Error Vertical navigation error Pressure altimeter setting error VFR flight plan IFR flight plan

Add FIRE Tags

Tags: Post Crash Fire Non-Fire Fumes Dangerous Goods Fire-Cabin Baggage origin Fire-Cargo origin Fire-Electrical origin Fire-Fuel origin Fire-Power Plant origin Fire-Underfloor origin Fire-Galley Fire-Wing De-Ice fluid contamination Electrical fumes - No fire Landing Gear Overheat

Add HF Tags

Tags: Aircraft acceptance ATC clearance error ATC Unit Co-ordination Authority Gradient Data use error Distraction Ergonomics Fatigue Flight / Cabin Crew Co-operation Flight Crew / Ground Crew Co-operation Flight Crew Incapacitation Flight Crew Visual Inspection Food Poisoning Gross Data Error not recognised Inappropriate ATC Communication Inappropriate crew response - skills deficiency Inappropriate crew response (automatics) Inappropriate crew response (technical fault) Ineffective Monitoring Maintenance Visual Inspection Manual Handling Pilot Medical Fitness Plan Continuation Bias Procedural non compliance Spatial Disorientation Stress Violation

Add GND Tags

Tags: Taxiway collision On gate collision Aircraft / Aircraft conflict Aircraft / Person conflict Aircraft / Vehicle conflict Aircraft / Object or Structure conflict ATC clearance error Ground de/anti icing Jet Blast / Prop wash Surface Friction Towed aircraft involved Aircraft Push Back Incorrect Parking Position Airbridge Positioning Both objects moving Wingtip clearance Centreline obscured Accepted ATC clearance not followed Surface Lighting control Hold Loading Passenger Loading Cargo Loading Fuel Loading Dangerous Goods Engine Ground Running Engine Powered Systems Test No Flight Crew on Board

Add LB Tags

Tags: Accepted ATC Clearance not followed SID bust Clearance readback error undetected TCAS RA response Manual flight Pressure altimeter setting error

Add LOC Tags

Tags: Airframe Structural Failure Significant Systems or Systems Control Failure Degraded flight instrument display Uncommanded AP disconnect AP Status Awareness Non-normal FBW flight control status Loss of Engine Power Crew Incapacitation Flight Management Error Flight Control Error Environmental Factors Bird or Animal Strike Aircraft Loading Malicious Interference Temporary Control Loss Extreme Bank Extreme Pitch Last Minute Collision Avoidance Hard landing Take off Trim Setting Incorrect Thrust Computed Unintended transitory terrain contact Collision Damage Incorrect Aircraft Configuration Aerodynamic Stall

Tags: Airframe Structural Failure Significant Systems or Systems Control Failure Degraded flight instrument display Uncommanded AP disconnect AP Status Awareness Non-normal FBW flight control status Loss of Engine Power Crew Incapacitation Flight Management Error Flight Control Error Environmental Factors Bird or Animal Strike Aircraft Loading Malicious Interference Temporary Control Loss Extreme Bank Extreme Pitch Last Minute Collision Avoidance Hard landing Take off Trim Setting Incorrect Thrust Computed Unintended transitory terrain contact Collision Damage Incorrect Aircraft Configuration Aerodynamic Stall

Add LOS Tags

Tags: TCAS RA Mis Flown Accepted ATC Clearance not followed See and Avoid Ineffective Required Separation not maintained Released to Own Separation Level Bust Lateral Navigation Error ATC Error Near Miss Lateral Offset in use Mid-Air Collision Uncommanded AP disconnect Military Aircraft involved Apparent de-selection of transponder Transponder non selection

Add RI Tags

Tags: ATC error Accepted ATC Clearance not followed Incursion pre Take off Incursion after Landing Runway Crossing Intersecting Runways Intersecting extended centrelines Towed aircraft involved Near Miss Ground Collision Phraseology Intentional Premature Rotation Vehicle Incursion

Add RE Tags

Tags: Overrun on Take Off Overrun on Landing Directional Control Undershoot on Landing Wrong Runway Excessive Airspeed RTO decision after V1 High Speed RTO (V above 80 but not above V1) Unable to rotate at VR Frozen Deposits Collision Avoidance Action Parallel Approach Operations Excess Water Depth Late Touchdown Significant Tailwind Component Significant Crosswind Component Thrust Reversers not fitted Landing Performance Assessment Off side of Runway Misalignment on runway Taxiway Take Off/Landing Runway Length Temporarily Reduced Intentional Premature Rotation Incorrect Aircraft Configuration Reduced Thrust Take Off

Add WAKE Tags

Tags: ICAO Standard Wake Separation prevailed ICAO Standard Wake Separation not met Accepted ATC clearance not followed Own separation In trail event Cross track event Pilot over compensation Intersection take off Intersecting extended centrelines Intersecting runways

Add WX Tags

Tags: In Flight Airframe Icing In Flight Icing - Piston Engine In Flight Icing - Turbine Engine CAT encounter En route In-cloud air turbulence Hail damage Volcanic Ash Effects Sand/Dust limited IFV Fog In Cloud on Visual Clearance Precipitation-limited IFV Strong Surface Winds Mountain Waves Lightning Damage Low Level Windshear

Add EPR Tags

Tags: Emergency Descent Emergency Evacuation Airport Emergency Medical Response MAYDAY declaration PAN declaration “Emergency” declaration Slide Malfunction RFFS Procedures Evacuation difficulties in Water Delay in Declaration of Emergency

Tags: Emergency Descent Emergency Evacuation Airport Emergency Medical Response MAYDAY declaration PAN declaration “Emergency” declaration Slide Malfunction RFFS Procedures Evacuation difficulties in Water Delay in Declaration of Emergency

Add CS Tags

Tags: Disruptive Pax Turbulence Injury - Cabin Crew Turbulence Injury - Pax with Seat Belts on Turbulence Injury - Pax with Seat Belts off Cabin Stowage - Pax Items Toilet compartment fire Cabin furnishings fire Evacuation slides deployed Pax oxygen mask drop Unauthorised PED use IFE fire Flight deck comms difficulty Cabin air contamination Malicious interference Hand held extinguisher used Evacuation on Cabin Crew initiative Flight Crew Evacuation Command Cabin Crew Incapacitation Cabin Crew Medical Fitness Passenger Illness Faulty or misused PED

Add AW Tags

System(s): Airframe Air Conditioning and Pressurisation Autoflight Communications Electrical Power Equipment / Furnishings Fire Protection Flight Controls Fuel Hydraulic Power Ice and Rain Protection Indicating / Recording Systems Landing Gear Landing Lights Navigation Oxygen Airborne Auxiliary Power (APU) Propellers Rotors Engine - General Engine Fuel and Control Bleed Air Other Emergency Evacuation Contributor(s): Maintenance Error (valid guidance available) Maintenance Error (invalid guidance available) Inadequate Maintenance Schedule Inadequate Maintenance Inspection Inadequate QRH Drills OEM Design fault Damage Tolerance Contributing ADD Component Fault in service Component Fault after installation Pilot verbal-only defect communication Corrosion/Disbonding/Fatigue Cross Connection Engine Compressor Washing

System(s): Airframe Air Conditioning and Pressurisation Autoflight Communications Electrical Power Equipment / Furnishings Fire Protection Flight Controls Fuel Hydraulic Power Ice and Rain Protection Indicating / Recording Systems Landing Gear Landing Lights Navigation Oxygen Airborne Auxiliary Power (APU) Propellers Rotors Engine - General Engine Fuel and Control Bleed Air Other Emergency Evacuation Contributor(s): Maintenance Error (valid guidance available) Maintenance Error (invalid guidance available) Inadequate Maintenance Schedule Inadequate Maintenance Inspection Inadequate QRH Drills OEM Design fault Damage Tolerance Contributing ADD Component Fault in service Component Fault after installation Pilot verbal-only defect communication Corrosion/Disbonding/Fatigue Cross Connection Engine Compressor Washing

Add Safety Net Mitigation

Malfunction of Relevant Safety Net: None Yes No GPWS: None Effective Partially effective Available but ineffective TAWS: None Effective Partially effective Available but ineffective TAWS with RAAS: None Effective Partially effective Available but ineffective TCAS: None Effective Partially effective Available but ineffective STCA: None Effective Partially effective Available but ineffective MSAW: None Effective Partially effective Available but ineffective APM: None Effective Partially effective Available but ineffective APW: None Effective Partially effective Available but ineffective Mode 'S' EHS: None Effective Partially effective Available but ineffective Wind Shear Escape Guidance: None Effective Partially effective Available but ineffective Stall Protection: None Effective Partially effective Available but ineffective A-SMGCS: None Effective Partially effective Available but ineffective EMAS: None Effective Partially effective Available but ineffective TOCWS: None Effective Partially effective Available but ineffective

Add Causal Factor Group(s)

Causal Factor Group(s): Aircraft Operation Aircraft Technical Air Traffic Management Airport Operation

Causal Factor Group(s): Aircraft Operation Aircraft Technical Air Traffic Management Airport Operation

Add Safety Recommendations

Safety Recommendations: None Made Aircraft Operation Aircraft Airworthiness Air Traffic Management Airport Management

Safety Recommendations: None Made Aircraft Operation Aircraft Airworthiness Air Traffic Management Airport Management

Accident Report text:

==Description== On 7 October 2008, an [[A333|Airbus A330-300]] being operated by Qantas on a scheduled passenger flight from Singapore to Perth, Western Australia was in the cruise at FL370 with the [[Autopilot|AP]] engaged when one of the air data inertial reference units (ADIRUs)<ref name="flightcontrollaw">[[Flight Control Laws]]</ref> malfunctioned and two sudden uncommanded pitch downs followed. A PAN, later upgraded to a MAYDAY after the extent of occupant injuries became apparent, was declared to ATC and a diversion to Learmonth initiated with an approach and landing there about an hour later. Of the 315 occupants, 11 passengers and 1 cabin crew member were seriously injured and a further 99 passengers and 8 cabin crew received minor injuries. ==Investigation== An Investigation was carried out by the [[ATSB]]. [[FDR]], Quick access recorder (QAR) and [[CVR]] data was all successfully replayed to support the Investigation. A Preliminary Report and two Interim Factual Reports were published whilst the Investigation was in progress. The aircraft commander had been [[PF]] when, after a previously uneventful flight, an uncommanded AP1 disconnect occurred followed by a series of caution messages on the EICAM and transient activation of obviously false [[Stall|stall]] and over speed warnings. These cautions and warnings occurred frequently and continued for the remainder of the flight. The airspeed and altitude indications on the left main PFD (only) were also fluctuating. Although numerous ECAM caution messages were annunciated, none of them required urgent action, and none of them indicated any potential problems with the aircraft’s flight control system. Two minutes after the AP1 disconnect, the aircraft abruptly pitched nose down. FDR data showed that this was due to a sudden change in the position of the aircraft elevators, and that the aircraft reached a maximum nose-down pitch angle of 8.4°. The flight crew described the pitch-down movement as very abrupt, but smooth. It was considered not to be like turbulence-related movements and was solely in the pitching plane. Side stick back pressure to counteract the pitch was applied and after about 2 seconds the aircraft responded normally and recovery to the assigned altitude was accomplished. Overall, the aircraft descended 690 ft over a period of 23 seconds before regaining FL370. During the upset, the FDR recorded a peak vertical acceleration of -0.8g and a significant number of occupants were thrown around the cabin, resulting in both personal injuries and damage to cabin overhead fittings. The operating co pilot switched on the seat belt signs soon after the upset and made a PA announcement for passengers and cabin crew to return to their seats and fasten their seat belts immediately. Two and a half minutes after the first pitch down event, a second less severe one occurred while the crew were responding to the ECAM messages. The aircraft reached a maximum pitch angle of about 3.5° nose down and side stick back pressure to counter this was promptly applied. As with the first case, the action initially had no effect but soon afterwards, the aircraft responded normally. The aircraft descended 400 feet over a period of 15 seconds before regaining FL370. The aircraft commander noted that the auto trim was no longer working and decided to fly the aircraft manually with both AP and A/T disconnected, believing the aircraft flight control system to have reverted to Direct Law<ref name="flightcontrollaw"></ref>. In fact, although absence of auto trim is a feature of Direct Law, in this case, it had been lost as a consequence of the specific sequence of fault messages associated with the Flight Control Primary Computer (FCPC) and only reversion to Alternate Law<ref name="flightcontrollaw"></ref> had occurred. Soon after recovery from the second upset, the decision to make an en route diversion was made and a ‘PAN’ declared to ATC. The diversion to Learmonth was accomplished without further event other than the discovery that the extent of cabin injuries amongst unsecured passengers and crew was greater than had at first been appreciated. A descent was accomplished in the vicinity of the airfield before positioning for a visual approach and landing. [[File:FPA333.jpg|thumb|none|700px|Aircraft track and key events reproduced from the Official Report]] The Investigation concluded that a design limitation with the FCPC software had combined with an ADIRU failure to falsely activate corrective mechanisms and that this had caused the two uncommanded pitch-downs. It was considered that this design limitation had been a consequence of a failure scenario not being considered. It was noted that: “''The development process for a safety-critical system has many elements to minimise the risk (probability and consequences) of a design error. These include peer reviews of design requirements, and system safety assessment (SSA), testing and simulation activities that are done as part of the verification and validation processes. It is widely accepted that not all the potential failure modes and failure scenarios for complex systems can be identified in practice, and fault-tolerant design features are included in a system to reduce the risk of such problems.'' ''The A330/A340 FCPC algorithm for processing AOA data was redesigned after a problem was found with the initial algorithm during flight testing that was conducted before the aircraft type was certified. The redesign unintentionally introduced the design limitation in the algorithm, and the fault-tolerant features of the system were not able to fully mitigate the problem. The design limitation was not identified during the redesign activities.”'' It was noted that whilst the completed SSA had identified the failure that occurred (incorrect high AOA data leading to a pitch-down command) it had not identified the scenario that led to this condition on the investigated flight. In respect if the ADIRU1 fault, it was found to have transmitted a significant amount of incorrect data on inertial reference parameters to other systems, almost all of this data being invalid. It was considered probable that the ADIRU data-spike failure mode involved a problem with the data packaging and queuing within the ADIRU CPU module. The fault had caused numerous data anomalies including air data reference parameters being intermittently transmitted with the data or label of another parameter. Despite extensive testing and analysis, the Investigation was unable to establish the precise origins of the ADIRU1 failure but it was concluded that the ADIRU1 data-spike was probably not triggered by a software bug, a software corruption, a hardware fault, physical environmental factors (such as temperature or vibration), neither had it been due to electromagnetic interference. It was noted that the false AOA data had been able to confuse the FCPC processing algorithm which was unable to respond to a scenario where there were multiple spikes in AOA from a single ADIRU at the elapsed time intervals which occurred. It was considered likely that each of the intermittent data spikes had been generated when the faulty ADIRU CPU combined the data value from one parameter with the label for a different parameter. The failure mode was probably initiated by a single, rare type of internal or external trigger event combined with a marginal susceptibility to that type of event within a hardware component. The investigated occurrence was identified as the only known case where this design fault had led to a pitch-down command in over 28 million flight hours on A330/A340 aircraft. However, although all three known occurrences of ADIRU data-spike failure were found to have occurred on two A330 aircraft also operated by Qantas, no contributory factors related to operator-specific aircraft configuration, operating practices, or maintenance practices had been identified. It was considered that the flight crew response to what happened had demonstrated both “sound judgment and a professional approach”. In respect of the injuries to passengers, it was noted that at least 23 passengers were not seated at the time of the first in-flight upset but that there were also more than 60 other passengers who were seated without their seat belts fastened. Whilst it was accepted that a few of these had been in the process of getting into or out of their seats, it was concluded that the majority had not appeared to have a “valid” reason for not wearing their seat belts. Eleven '''Safety Issues''', one categorised as ‘Significant’ and ten as ‘Minor’, were identified by the Investigation as follows: * There was a limitation in the algorithm used by the A330/A340 flight control primary computers for processing angle of attack (AOA) data. This limitation meant that, in a very specific situation, multiple AOA spikes from only one of the three air data inertial reference units could result in a nose-down elevator command. [''Significant safety issue''] * When developing the A330/A340 flight control primary computer software in the early 1990s, the aircraft manufacturer’s system safety assessment and other development processes did not fully consider the potential effects of frequent spikes in the data from an air data inertial reference unit. [''Minor safety issue''] * One of the aircraft’s three air data inertial reference units (ADIRU 1) exhibited a data-spike failure mode, during which it transmitted a significant amount of incorrect data on air data parameters to other aircraft systems, without flagging that this data was invalid. The invalid data included frequent spikes in angle of attack data. Including the 7 October 2008 occurrence, there have been three occurrences of the same failure mode on LTN-101 ADIRUs, all on A330 aircraft. [''Minor safety issue''] * For the data-spike failure mode, the built-in test equipment of the LTN-101 air data inertial reference unit was not effective, for air data parameters, in detecting the problem, communicating appropriate fault information, and flagging affected data as invalid. [''Minor safety issue''] * Although passengers are routinely reminded to keep their seat belts fastened during flight whenever they are seated, a significant number of passengers have not followed this advice. At the time of the first in-flight upset, more than 60 of the 303 passengers were seated without their seat belts fastened. [''Minor safety issue''] * In recent years there have been developments in guidance materials for system development processes and research into new approaches for system safety assessments. However, there has been limited research that has systematically evaluated how design engineers and safety analysts conduct their evaluations of systems, and how the design of their tasks, tools, training and guidance material can be improved so that the likelihood of design errors is minimised. [''Minor safety issue''] * Single event effects (SEE) have the potential to adversely affect avionics systems that have not been specifically designed to be resilient to this hazard. There were no specific certification requirements for SEE, and until recently there was no formal guidance material available for addressing SEE during the design process. [''Minor safety issue''] * The LTN-101 air data inertial reference unit (ADIRU) model had a demonstrated susceptibility to single event effects (SEE). The consideration of SEE during the design process was consistent with industry practice at the time the unit was developed, and the overall fault rates of the ADIRU were within the relevant design objectives. [''Minor safety issue''] * Industry practices for tracking faults or performance problems with line-replaceable units were limited, unless the units are removed for examination. Consequently, the manufacturers of aircraft equipment have incomplete information for identifying patterns or trends that can be used to improve the safety, availability or reliability of the units. [''Minor safety issue''] * There has been very little research conducted into the factors influencing passengers’ use of seat belts when the seat-belt sign is not illuminated, and the effectiveness of different techniques to increase the use of seat belts. [''Minor safety issue''] * Although passengers are routinely advised after takeoff to wear their seat belts when seated, this advice typically does not reinforce how the seat belts should be worn. [''Minor safety issue''] '''Safety Action''' in respect of the identified safety issues was noted. In respect of the single ‘Significant Safety Issue’, the Airbus response was noted to have commenced a week after the event with the issue of temporary revisions to flight crew procedures for all A330 and A340 aircraft fitted with the incident ADIRUs. These required that in the event of a NAV IR fault or red ATT flag on either PFD, the ADR part of the relevant ADIRU should be selected OFF and then the relevant IR part of the relevant ADIRU should also be selected OFF. An associated temporary revision to the MMML was also issued. All revised temporary procedures for both aircraft types were mandated by certification authority [[EASA]], as were two subsequent modifications to the initial procedure changes. Subsequently, Airbus issued SBs for fitment of replacement FCPCs and once this retrofit has been completed, the temporary procedure revisions will be withdrawn The '''Final Report''' of the Investigation [http://www.skybrary.aero/bookshelf/books/1760.pdf Aviation Occurrence Investigation AO-2008-070 Final] was released on 19 December 2011. ==References== <references/> ==Related Articles== * [[Loss of Control]] * [[Recovery from Unusual Aircraft Attitudes]] * [[Airworthiness]] * [[Airworthiness - The System]] * [[Damage Tolerance]] * [[Defect Assessment]]

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