Incident Boeing 737-8Q8 (WL) C-FTAH, 13 Mar 2011
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ASN Wikibase Occurrence # 191786
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Type:Silhouette image of generic B738 model; specific model in this crash may look slightly different    
Boeing 737-8Q8 (WL)
Owner/operator:Sunwing Airlines
Registration: C-FTAH
MSN: 29351/1471
Fatalities:Fatalities: 0 / Occupants: 196
Other fatalities:0
Aircraft damage: None
Location:Toronto–Lester B. Pearson International Airport, Ontario (YYZ) -   Canada
Phase: Take off
Nature:Passenger - Scheduled
Departure airport:Toronto–Lester B. Pearson International Airport, Ontario (YYZ)
Destination airport:Cozumel International Airport
Investigating agency: TSB Canada
Confidence Rating: Information verified through data from accident investigation authorities
A Boeing 737-8Q8 was operating as Sunwing Airlines flight 531 from Toronto–Lester B. Pearson International Airport, Ontario, Canada to
Cozumel International Airport, Mexico, with 189 passengers and 7 crew members on board.
During the take-off run, at about 90 knots indicated airspeed, the autothrottle disengaged after take-off thrust was set. As the aircraft approached the critical engine failure recognition speed, the first officer, who was the pilot flying, noticed an AIRSPEED DISAGREE alert and transferred control of the aircraft to the captain, who then continued the take-off. During the initial climb, the aircraft received a stall warning (stick shaker), followed by a flight director command to pitch to a 5° nose-down attitude. The take-off was being conducted in visual conditions, allowing the captain to determine that the flight director commands were erroneous. The captain ignored the flight director commands and maintained a climbing attitude. The crew advised the air traffic controller of a technical problem that required a return to Toronto. The crew did not declare an emergency, but requested that aircraft rescue and firefighting services be placed on standby due to the overweight landing. The occurrence took place at 06:57 Eastern Daylight Time, during hours of darkness. The aircraft landed at 07:23, during hours of civil twilight.

Findings as to Causes and Contributing Factors:
1. A failure in the right pitot-static system caused the output of erroneous airspeed data from the right air data and inertial reference unit. This resulted in erroneous airspeed indications, stall warnings, and for unknown reasons, misleading flight director commands being displayed on the aircraft instruments during take-off and initial climb.

Findings as to Risk:
1. When an operator’s proactive and reactive safety management system processes do not trigger a risk assessment, there is an increased risk that hazards will not be mitigated.
2. Operators that do not recognize this type of event as a reportable aviation occurrence may not report it, conduct an investigation to further analyze or mitigate the risk, or preserve data from the digital flight data recorder to facilitate an investigation.
3. If operators do not thoroughly document aircraft malfunctions, there is an increased risk that aircraft deficiencies will not be completely corrected before the aircraft is returned to service.
4. If cockpit and data recordings are not available to an investigation, this may preclude the identification and communication of safety deficiencies to advance transportation safety.
5. The acceptance by flight crews and companies of known equipment problems, such as the boom and mask microphones switching problem, could put safety of flight at risk.



Accident investigation:
Investigating agency: TSB Canada
Status: Investigation completed
Download report: Final report
Other occurrences involving this aircraft

21 Feb 2008 C-FTAH Sunwing Airlines 0 En route YYZ-FLL min
Loss of pressurization.

Revision history:

01-Dec-2016 15:20 harro Added

Corrections or additions? ... Edit this accident description

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