SB20, vicinity Sumburgh, UK 2014

SB20, vicinity Sumburgh, UK 2014

Summary

On 15 December 2014, the Captain of a Saab 2000 lost control of his serviceable aircraft after a lightning strike when he attempted to control the aircraft manually without first disconnecting the autopilot and despite the annunciation of a series of related alerts. The aircraft descended from 4,000 feet to 1,100 feet at up to 9,500 fpm and 80 knots above Vmo. A fortuitous transient data transmission fault caused autopilot disconnection making it possible to respond to EGPWS 'SINK RATE' and 'PULL UP' Warnings. The Investigation concluded that limitations on autopilot disconnection by pilot override were contrary to the type certification of most other transport aircraft.

Description

On 15 December 2014, a Saab 2000 (G-LGNO) being operated by Loganair on a Flybe-branded scheduled domestic passenger flight from Aberdeen to Sumburgh was struck by lightning shortly after discontinuing an ILS approach at destination at night in IMC. A MAYDAY was declared and acknowledged on account of the lighting strike and an interlude, during which the crew suspected that the strike had compromised aircraft pitch control, followed with loss of control and a rapid dive at high speed occurred to 1,100 feet over the sea with recovery only commenced after EGPWS 'PULL UP' and 'SINK RATE' warnings had occurred. A diversion back to Aberdeen was then flown without further event. There were no injuries to any of the 33 occupants and only superficial airframe damage consequent to the lightning strike.

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