Description

On 10 January 2008, an Airbus A319-100 being operated by Air Canada on a scheduled passenger flight from Victoria BC to Toronto in night Visual Meteorological Conditions (VMC) was west of Oroville Washington USA when it was subjected to sudden jolts and then a series of rolls which resulted in an unintended descent of 1400 feet before straight and level flight was regained. During the episode, cabin service was in progress and seat belt signs were off. Cabin service carts were lifted off the floor and struck the ceiling above occupied passenger seats before coming back to rest in the aisle. The flight crew, suspecting a flight control abnormality, declared an emergency and diverted uneventfully, and without further use of the autopilot, to Calgary. Three of the 88 occupants sustained serious injuries and eight sustained minor injuries as a result of falls and collisions with aircraft furnishings.

Investigation

An Investigation was carried out by the Canadian TSB. It was established that the aircraft had been climbing in accordance with its ATC clearance from FL350 to cruise altitude FL370 behind a United Airlines operated Boeing 747-400 en route from Hong Kong to Chicago and level at FL 370 and that the incident had occurred as the A319 had passed FL366 at a distance of 10.7 nm in trail behind the Boeing. The relative tracks are shown on the diagram below taken from the Official Report.