Pilots of a White Airways ATR 72-600 failed to follow sterile cockpit procedures and allowed the aircraft to gain excessive energy before the turboprop porpoised on touchdown at Lisbon, suffering serious damage.
As the aircraft, operating a TAP Portugal service, descended towards runway 21 it encountered rain and winds gusting up to 20kt, although the wind conditions were within operating limits for the turboprop.
Investigation authority GPIAAF says the ATR’s airspeed had crept to 116kt – above the 101kt approach speed – but a call-out from the first officer, who was monitoring, did not elicit a response from the captain.
Analysis of the ground speed shows it increased from 94kt at 1,000ft, to 108kt at the threshold, and 110kt just before the first touchdown.
The ATR bounced three times. After the first, it landed on its nose-gear, fracturing the axle and causing the right-hand wheel to separate. The second bounce led the aircraft to porpoise onto its nose-gear again, whereupon the other wheel detached and the aircraft bounced again, settling only after the fourth contact.
As well as the loss of both nose-wheels the ATR sustained substantial damage to the primary structure of its forward fuselage, although none of the 24 occupants was injured.
GPIAAF says the crew had maintained conversations which were “not relevant” to the conduct of the flight during restricted phases, in breach of sterile-cockpit procedures.
Standard operating procedures to monitor progress of the approach, notably the aircraft speed, were not followed by the captain.
As the aircraft flared for touchdown the excessive energy caused it to float and the captain “forced” the aircraft to land at speeds higher than those calculated and established in the flight manual.
It touched down 700m from the threshold and, having finally settled after the third bounce, it scored the runway surface with the nose-gear leg before coming to rest 1,660m from the threshold.
The inquiry says the captain’s knowledge and understanding of the ATR 72’s bounced-landing recovery technique was “inadequate”.
“Incorrect aircraft handling and landing technique resulted in a porpoise landing,” it states in its conclusions over the 22 October 2016 accident.
It suggests the crew might have been suffering the effects of fatigue after six flight legs, even though their duty time was within regulatory limits.