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15 Feb 2021 - Boeing issue FOTB on the prevention of aircraft upsets

Boeing have on 15 Feb 2021 issued Flight Ops Technical Bulletin 737-12-2 Rev 1, “To reinforce active flight crew monitoring of airplane state and flight path management to prevent airplane upsets.

It would appear that this bulletin has been released in response to the Sriwijaya Air 737-500 accident on 9 Jan 2021.

Excerpts from the bulletin include:

"Loss of Control In-flight (LOC-I) remains the single greatest cause of fatalities in commercial aviation. This bulletin is meant to reinforce the importance for active monitoring of the airplane state while managing the airplane flight path. Pilots should be familiar with the Upset Recovery maneuver in the Quick Reference Handbook (QRH) and the extensive information about Upset Prevention and Recovery in the Flight Crew Training Manual (FCTM). Continual crew awareness of airplane attitude, airspeed, flight control position and thrust settings is fundamental for airplane upset prevention and can reduce the effect of startle or surprise caused by rapid unexpected changes."

Airplane upsets can be caused by a variety of issues such as:
• External environmental events, (windshear, clear air turbulence, wake turbulence, thunderstorms, icing conditions etc.)
• Airplane damage. (bird impact, lightning strikes, structural failure)
• Airplane systems. (flight control/automation issues, flap and thrust asymmetries)
• Incorrect or unexpected flight control inputs to potential airplane upsets

"Upset prevention involves the active participation of both pilots… Active monitoring skills are essential to facilitate early detection of conditions that can lead to an airplane upset.”

“Minor excursions such as simply overbanking in a turn or flying slow on approach can progress to a larger divergence from the intended flight path and lead to an airplane upset condition and potential loss of control.”

The bulletin also addresses complacency: “Highly automated and reliable flight control systems have greatly reduced pilot workloads, but the requirement for monitoring complex systems has increased.”

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*** Updated 14 Nov 2021 ***

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PK-CLC track

The track of PK-CLC showing loss of control

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