US investigators believe the pilot of an Embraer Phenom 300 did not de-ice the aircraft before it stalled, rolled to the left, and crashed immediately after lift-off from Provo municipal airport in Utah.
The pilot did not survive the accident, and the three passengers were injured, two of them seriously.
Investigators state that the Phenom (N555NR) had been rolled out of a heated hangar and refuelled on 2 January 2023, but remained outside for about 40min before take-off.
Water droplets had been “visible on both wings”, says the National Transportation Safety Board, and weather information for the airport showed a temperature of -1°C (30.2°F), freezing mist and light snow.
These conditions would have allowed ice accumulation on the upper surfaces of the wings, fuselage, and tail surfaces in the time the jet was outside.
But at no time was the aircraft de-iced or given anti-ice treatment.
The aircraft’s manager told the inquiry that the jet would typically undergo pre-flight preparation inside the hangar, leaving only refuelling to be performed before boarding.
He stated that de-icing had only been needed twice in the previous eight years and, while the pilot had mentioned de-icing on the day, no call was made to fixed-base operators requesting it.
The Phenom was fitted with a wing and horizontal stabiliser anti-icing system, activated by a three-position ‘wing stab’ switch near the lower-right corner of the left-hand primary flight display.
Flight-recorder information indicates the switch was turned on about 9min after engine start, while the pilot was running a checklist.
As the switch was turned on, the pilot remarked, “We’re gonna get wing stab arm,” followed by, “Wing stab arm, we got that.”
The switch was then turned off – with an audible click – and it was recorded as remaining off for the rest of the flight. Although investigators found the switch in the ‘on’ position in the wreckage, the inquiry believes this resulted from the accident sequence – the switch panel had separated from other cockpit instruments.
“It could not be determined why the ‘wing stab’ ice-protection switch was turned off,” says the inquiry.
As the Phenom lifted off from runway 13, it immediately rolled to the left, reaching a maximum altitude of just 14ft, and its stall warning activated. The aircraft banked 60° left, its left wing climbing “little, if at all”, says the inquiry.
It struck the runway surface, with scrape marks observed arcing to the left edge about 3,126ft from the approach end. The jet ultimately crashed 100ft off the left edge, losing its wings and engines in the impact.
Failure to de-ice the aircraft, the investigation concludes, led to departure with an ice-contaminated wing, and the subsequent stall.
