German investigators have disclosed that a LATAM Airlines Boeing 767-300ER freighter reached a steep nose-up pitch of 48°, and started to stall, during a windshear-escape manoeuvre on approach to Frankfurt.
The aircraft had been arriving from Amsterdam on 20 June and had stabilised on the ILS Category I approach to Frankfurt Main’s runway 25L.
As the twinjet descended through 800ft, the onset of rain rapidly reduced the crew’s visibility and the captain took over from the first officer as the flying pilot. Autothrust and autopilot were disengaged about 0.7nm from the runway.
With visual references to the runway lost, the crew aborted the approach after reaching the decision height.
But as the captain initiated a go-around, a windshear warning was issued in the cockpit and the captain switched to a windshear-escape manoeuvre – entering a climb and commanding maximum thrust.
Preliminary findings from German investigation authority BFU state that, as the aircraft climbed to 2,735ft it reached a nose-up pitch of 48°, at an airspeed of 117kt, some 43s after the windshear alert.
Quick-reference information on the windshear-escape manoeuvre points to a target pitch of 15° in manual flight.
With the excessive nose-up attitude, and its flaps in the 20° setting, the aircraft’s stall-warning and stick-shaker activated, and the airspeed bled away to 86kt with a groundspeed of 60kt.
Although the aircraft’s pitch reduced to 16°, its angle-of-attack increased to nearly 21° and the loss of lift caused it to descend rapidly.
BFU says the crew “temporarily lost control of the aircraft” and its rate of descent increased to 5,500ft/min.
The pilots told the inquiry that they initiated a stall-recovery procedure. About 20s after the stall warning, having lost about 1,000ft in height, the aircraft stopped descending at 1,913ft.
After stabilising the aircraft’s altitude and flightpath the captain initiated another climb to 5,000ft and then to 9,000ft before conducting a second approach and landing some 37min after the initial go-around.
None of the three crew members, the only occupants of the aircraft, was injured. The flight, carrying 20.4t of freight, was the first of the day for both pilots, who each had substantial experience on the 767 – the captain with nearly 11,100h and the first officer with 3,000h.
BFU says the aircraft – a General Electric CF6-powered airframe, CC-CXK, originally delivered to LATAM as a passenger jet in 2010 – was not damaged in the incident. The inquiry has yet to reach formal conclusions on the event.