Veritastech Pilot Academy

NTSB Releases Final Report on Utah Hawker Accident

The National Transportation Safety Board final report on the fatal crash of a Hawker 900XP over Westwater, Utah, in February notes the crew attempted to perform stall tests in icing conditions, even though they lacked experience performing the tests in the Hawker and were unfamiliar with the stall characteristics, which led to a loss of control and the death of both the pilot and copilot.

According to the report, two AIRMETs were issued about two and a half hours before the accident flight for moderate icing throughout the airplane’s climb and cruise altitude for the stall test. In addition, video showed that the departure airport was surrounded by obscuration and precipitation during takeoff.

Investigators said evidence showed that the flight crew was aware of the presence of sleet and winter conditions before departure during their interactions with maintenance personnel. The presence of these conditions should have given the flight crew pause before they executed the stall test, which required visual meteorological conditions and no icing, according to the airplane’s pilot’s operating manual (POM).

The Details

On February 7, 2024, the airplane, owned by Vici Aviation and operated by Clay Lacy Aviation., was on a repositioning flight, heading from Grand Junction Regional Airport (KGJT) in Colorado, where it had just undergone maintenance, to its base at Tacoma Narrows Airport (KTIW) in Gig Harbor, Washington.

According to the NTSB, the aircraft was at West Star Aviation at KGJT for routine maintenance, which included an inspection of the wing leading edges and TKS panels looking for cracks and corrosion.

The flight crew, composed of the pilot in command (PIC) and second in command (SIC), was conducting a stall test in the airplane following the recent removal, inspection, and reinstallation of the wing leading edges and deice panels as part of routine maintenance.

The airplane took off from KGJT and turned toward the northeast. Two AIRMETs were issued about two and a half hours before the accident flight for moderate icing throughout the airplane’s climb and cruise altitude for the stall test. In addition, video of the departure airport at the time of the Hawker’s takeoff showed the field was surrounded by obscuration and precipitation, and the flight crew was aware of the presence of sleet and “storm” conditions before departure during their interactions with maintenance personnel.

The stall test conditions required by the POM include having an empty ventral tank, an operative stall identification system, and the autopilot off.

The aircraft took off normally and climbed to an altitude of 20,000 feet msl, where the crew then began the stall tests. According to the flight data recorder and the cockpit voice recorder, the pilots did not follow the recommended cloud clearance and height limitations prescribed by the stall test procedure in the POM.

The flight crew knowingly chose to execute the stall test above clouds, which put them 2,000 feet above the prescribed maximum altitude. The NTSB report also noted there was no evidence that the flight crew attempted to verify that the external surfaces were free of ice after flying through icing conditions despite the airplane being equipped with an ice detection spotlight system that could have been used to illuminate the wing fairings. It was noted that the airplane was also equipped with an ice detector that had to be manually activated by the flight crew as it was not directly connected to the airframe ice protection system.

“The presence of these conditions should have given the flight crew pause before they executed the stall test, which required visual meteorological conditions and no icing according to the airplane’s pilot’s operating manual (POM),” the NTSB report noted.

The flight data showed no anomalies with the flight controls or engines, as the flight control surface movements were consistent with the flight control inputs and engine performance matched the power lever movement.

The airplane decelerated and its pitch attitude increased, consistent with the flight crew preparing to perform their planned post-maintenance stall warning and identification system checks.

“The airspeed then slowed further, with flaps retracted for the first system check,” the report noted. “Performance calculations showed that the stick shaker activated about 117.5 [knots], 1 knot below the activation speed for the stick shaker at flaps zero. The stick pusher then activated at 113.5 [knots], 3 [knots] above the stick pusher activation speed.”

“Given the airplane’s weight and load factor, the shaker and pusher both activated at appropriate speeds; however, the airplane entered the stall at the same time the stick shaker activated, which provided no warning to the flight crew.”

According to the NTSB, the correct stall warning sequence should be “stick shaker, stick pusher, then, if the pilot does not attempt a stall recovery, stall entry.”

The report continued: “After the airplane entered the stall, the flight crew attempted to break the stall by inputting full left-wing-down aileron when the airplane abruptly banked right and applied full power and full aft control column, which aggravated the aerodynamic stall/spin.”

The incorrect response on the part of the flight crew suggests they were insufficiently trained for the flight, and the brief guidance from the POM provided no clear instructions for the possible consequences of “unacceptable stall characteristics” referenced as a cautionary note or a proper recovery.

The stall section of the POM states that “pilots conducting stall checks should have prior experience in performing stalls in the Hawker and must be prepared for unacceptable stall behavior at any point leading up to and throughout the maneuver.”

A review of the crew’s training records revealed in the previous year they had attended simulator training at a commercial facility for the SIC’s initial training and the PIC’s recurrent training. These courses cover the operation of the stall warning and identification system consisting of the shaker and pusher, and the training focuses on recognizing and avoiding stalls, as the simulator is not designed to teach full stalls, and cannot prepare the crew for an uncommanded roll, although the POM warns of this.

It was noted the PIC had participated in a stall test flight four years earlier, but the SIC had not participated in a stall test. The NTSB noted, given this information, “it is unlikely that the flight crewmembers’ simulator training on the stall warning and identification system and the PIC’s previous participation in a stall test flight adequately prepared them to safely conduct a stall flight test or address any unacceptable stall behavior.”

Investigators stated that the stall warning sequence for the accident flight, with the stall occurring at the same time the stick shaker activated, was likely due to a degradation in the relationship between lift and angle of attack (AOA) from wing contamination, either by icing or the airplane’s recent maintenance.

Based on the weather at the time of the accident and the fact the aircraft had to climb from 5,000 feet to 16,700 feet msl through clouds and precipitation to get to altitude, it is possible the Hawker accreted up to 1 millimeter of ice on the wings during the climb.

As pilots learn in private ground school, even a thin layer of ice can reduce lift by up to 40 percent.

The aircraft entered a flat spin from which it did not recover. It hit the ground and fragmented, then caught fire. This prevented a complete and thorough wreckage examination of the airframe and engines.

The Timeline

10:36:41: The SIC reported to the PIC that anti-ice was off while the airplane was on the ground before departure.

10:37: ADS-B and flight data recorder (FDR) data indicated that the airplane takes off from KGJT and begins a climb to the southeast.

10:38:45: The flight crew requests a block altitude from ATC in the “mid-teens for about 10 minutes,” and the SIC reports the “anti-ice is off.”

10:39:54: The PIC tells the SIC, “We’ll request an altitude once we get above in VMC-C.”The aircraft makes a turn to the northwest and continues to climb.

10:42:25: The SIC asks Denver Center for a block of altitude from FL 180 to FL 200. Center approves the altitude block. The Hawker climbs and levels off at 20,000 feet msl.

10:44:00: The FDR shows airspeed decreasing from 219 knots as the airplane’s pitch attitude and AOA (angle of attack) begin to increase.

10:44:41: The flight crew begins to discuss the stall test, then the SIC asks, “So we’re taking indicated, right?” to which the PIC responds, “Ah, yeah, indicated. We’re lookin’ for shaker, pusher. I’ll call mark on pusher if you can’t see it for some reason.”

10:45:01: The autopilot is disconnected.

10:45:51: A sound consistent with the gear warning horn is heard, followed by an acknowledgment from the PIC.

10:46:33: The cockpit area microphone records a sound consistent with the stick shaker, and the SIC reports “one nineteen” as the airplane’s pitch attitude continues to increase while airspeed simultaneously decreases.

10:46:37: While decelerating from 118 knots, at an AOA of 0.91 percent and 0.93 percent for the right and left, respectively, and a pitch attitude of 15.12 degrees for both the right and left, Stall Valve A opened. The CVR records a rattling sound that was accompanied by the sound of the stick shaker.

1046:47: The flight track data show the airplane began a rapid descent in a pattern resembling the shape of a corkscrew. The airplane makes multiple circular rotations before ending at 10:47:44.

The NTSB found the probable cause of the accident was the flight crew’s decision to conduct a post-maintenance stall test in an area of icing conditions, which resulted in wing contamination that significantly degraded the airplane’s critical angle of attack.

The completed NTSB final report can be found below:

Scroll to Top