French investigators have determined that an Embraer Phenom 100 was destroyed in a hard landing after its crew persisted with an approach to Paris Le Bourget in icing conditions.
The inquiry found that the aircraft’s weight and configuration would have prevented the aircraft from landing at Le Bourget if the crew had complied with the manufacturer’s icing approach procedures.
This was because – if a single-engined go-around was required – the aircraft’s climb rate would have been insufficient to clear obstacles. The available landing distance was also less than the aircraft would have required.
French investigation authority BEA says the crew was aware of these limitation before take-off, and that continuous activation of the de-icing system would have demanded a diversion from Le Bourget.
BEA says strict compliance with the manufacturer’s procedure made meeting the airport’s operational constraints “impossible”, and it highlights that pilots can face “difficulty” in making decisions about the best use of de-icing systems in icing conditions.
Although the weather information for Le Bourget indicated the presence of severe icing between 3,000-5,000ft, the crew opted to carry out procedures for an approach to runway 27 in non-icing conditions, but taking steps to check that ice was not building up on the aircraft.
The crew selected an approach reference speed of 97kt – close to the stall speed in icing – rather than the 119kt which would have been necessary with the de-icing systems engaged.
BEA analysis found that full activation of the de-icing systems would have required a landing distance 450m greater than that available for runway 27. It says Le Bourget’s runway 25 would similarly have been 200m too short.
The crew activated engine anti-icing and windshield de-icing during the descent and, after levelling at 3,000ft, engaged the pneumatic anti-ice wing and horizontal stabiliser boots for 21s. Both pilots witnessed built-up ice breaking up.
As the aircraft neared the runway, it passed through the radio-altimeter height of 50ft and its angle-of-attack increased from 10° to 28° while its airspeed declined to 90kt.
BEA says the jet “abruptly sunk” and its descent rate increased to 960ft/min. A stall alarm sound in the cockpit, and the aircraft stalled on very short final with a right bank of 10°.
It contacted the runway hard, and its right-hand landing-gear fractured, puncturing the right wing fuel tank.
Fire broke out at the wing root and near the engines, the nose-gear was damaged, and the aircraft slid along the runway for over 1,000m before yawing some 110° and coming to a halt off the left edge.
Neither pilot, nor the single passenger on board the Luxwing-operated aircraft (9H-FAM), was injured in the 8 February 2021 accident.
BEA says the captain explained that the approach strategy was a “standard adaptation” of the procedure.
“The crew indicated that they observed, through the cockpit window, that the ice which had built up on wing leading-edges had broken up,” it states. “They then de-activated the de-ice system and did not active it again.
“This decision was solely based on the visual observation of the wing leading-edges.”
BEA says ice had clearly formed on the aircraft during the descent but either the pilots did not realise the extent of contamination – possibly due to light conditions and cloud – or they stopped actively monitoring the situation, or simply did underestimated the consequence of any build-up.
The de-activation of the de-icing system could have meant ice remained on the horizontal stabiliser, or built up on the aircraft at the end of the approach.
“Just before the impact, the aircraft was flying in low-speed and high angle-of-attack envelopes where the aircraft was likely to stall in case of ice contamination of its structure,” says BEA.
“Recorded flight data did not enable the exact degree of contamination to be determined, but the presence of ice on the leading-edges of the wings and horizontal stabiliser observed after the accident confirmed that ice had built up on the aircraft.”