Pilot, safety expert, consultant, and aviation journalist Stuart “Kipp” Lau writes about flight safety and airmanship for AIN.

Contributor - Safety

Stuart “Kipp” Lau

During a 20-month period, two Hawker business jets crashed during post-maintenance test flights. Each was required by the manufacturer to undergo a stall test flight following a routine four-year maintenance inspection; in both cases, the aircraft entered an aerodynamic stall, and the pilots—although qualified to fly the aircraft—were unprepared to safely address the adverse stall behavior encountered.
NTSB, through its investigations, found three additional incidents involving the aircraft type. In January 2026, the board published a report (Aviation Investigation Report AIR-26-01) that made several urgent safety recommendations to the manufacturer, the FAA, and NBAA. NTSB found flight crews unprepared for post-maintenance stall test flights in Hawker airplanes, due to insufficient training and procedural guidance from the manufacturer.
Former Hawker Beechcraft chief test pilot Gary Grommet, during an NTSB interview, expanded on the stall test procedures and requirements. He found that “the requirements in the maintenance manual were ambiguous” and the wording appeared biased toward the qualification that any pilot—not a trained factory test pilot—with experience performing stalls in the Hawker may perform that stall test.
To date, Grommet has performed more than 400 stall test flights in Hawker aircraft: 100 while employed by the OEM and the remainder as a contracted flight test pilot. Grommet does not believe that the guidance in the Hawker maintenance and flight manuals is the industry standard because the pilot would then need procedures, tolerances, and training to determine that the stall characteristics of the aircraft (during the test flight) satisfied airworthiness requirements.
According to Grommet, to mitigate the risk associated with a Hawker stall test flight, a detailed flight test plan is required to be briefed, followed, and flown by a highly qualified pilot with flight test experience.
The complete NTSB Operational Factors/Human Performance interview with Grommet is available in the docket of the investigation into one of the Hawker accidents, registration N900VA (<a href="https://data.ntsb.gov/Docket?ProjectID=193761">NTSB WPR24FA083</a>).
<h2>Hawker 800XP Crash in Michigan</h2>
On Oct. 16, 2025, a Raytheon Hawker 800XP (registration XA-JMR) crashed near Bath Township, Michigan, approximately 8 nm northeast of Capital Region International Airport in Lansing, Michigan (KLAN). The pilot, copilot, and a maintenance technician from the MRO were fatally injured.
According to the NTSB’s preliminary report, the aircraft, which was owned and operated by a Mexican charter company, had just completed routine maintenance at Duncan Aviation’s facility in Battle Creek, Michigan (KBTL). One inspection required the removal of the wing leading edges and TKS ice protection panels for a visual inspection for cracks and signs of corrosion. Per the manufacturer’s structural repair manual (SRM), a post-maintenance stall test flight was required prior to return to service.
According to the NTSB’s preliminary report, the aircraft departed KBTL and entered a left climbing turn to the northeast. The flight crew asked air traffic control for a block altitude from FL140 to FL160. Once level at FL150, the aircraft began a rapid descent. Cleveland Center queried the aircraft, and the pilots responded, “We are in a…” followed shortly by a transmission in Spanish, which translated to “in a stall, recovering, sorry…” There were no further transmissions to ATC from the accident flight crew. The aircraft, according to the NTSB, impacted the ground in “relatively flat attitude.”
According to Duncan Aviation personnel, the two pilots were the primary crew of the accident aircraft. Before the completion of maintenance, the captain was provided with a list of experienced test pilots to perform the post-maintenance stall test flight. Unable to connect with an experienced contracted flight test pilot, the flight crew instead flew the accident stall test themselves.
NTSB reported that both crew members recently completed simulator training at a commercial training facility. The stall training included stall prevention procedures, stall recovery, and stick pusher demonstrations; this training was focused on recognizing and avoiding stalls.

<h2>Hawker 900XP Crash in Utah</h2>
The NTSB investigation into the Hawker 800XP accident in Michigan continues. However, the descent profile and other aspects of the flight are like another post-maintenance test flight that occurred 20 months earlier involving a Hawker 900XP crash in Utah.
According to the NTSB, on Feb. 7, 2024, a Hawker 900XP (N900VA) was destroyed when it crashed near Westwater, Utah. Both pilots were killed.
The aircraft was owned by Vici Aviation and was operated by Clay Lacy Aviation. Like the Hawker 800XP accident in Michigan, this aircraft had just completed routine maintenance that included removal of the wing leading edges and deicing panels to inspect for cracks and signs of corrosion. Before reentry into service, the aircraft would be required to have a post-maintenance stall test flight.
Both crewmembers of the Hawker 900XP accident flight were “the operator’s line pilots” and had attended separate simulator training sessions that covered stall warning and identification system (stick shaker and stick pusher) and focused on recognizing and avoiding stalls. It is unlikely that this simulator profile would prepare the pilots for a flight into the regime of an actual aerodynamic stall. According to the accident report, the pilot (PIC/pilot flying) had participated in a stall test flight four years before the accident as a SIC, and the copilot had never participated in a stall test flight.
The accident flight departed from Grand Junction Regional Airport (KGJT) and climbed to near the top of the flight crew’s requested block altitude of FL180 to FL200 before leveling off. At the time of departure, areas of clouds and precipitation were reported at KGJT.
The pilot operating manual (POM) requires a minimum altitude of 10,000 feet above ground, 10,000 feet above the clouds, and below 18,000 feet msl in VMC. Subject matter experts of Hawker stall flight tests recommend altitudes between 14,000 and 16,000 feet msl.
Flight data recorder and ADS-B data showed that the airplane entered a rapid, vertical descent consistent with a flat spin from which the flight crew did not recover aircraft control. Data indicates “the aircraft rolled through 360 degrees multiple times in a corkscrew descent.”
Investigators confirmed through flight data that the airplane was configured with flaps retracted and the autopilot off. Prior to entering the spin, the aircraft entered the stall at the same time the stick shaker activated before the stick pusher activated (the stick shaker is designed to activate 7% to 9% above stalling speed). In this scenario, there was no indication to the flight crew that the stall was imminent. NTSB determined that this stall identification and warning system activation sequence—the stall occurring at the same time as the stick shaker activation—was likely due to wing performance degradation from structural icing that occurred during the climb. &nbsp;&nbsp;
According to flight data for the accident flight, following the stall, the aircraft abruptly rolled to the right, the flight crew responded with full left wing down aileron input, full power, and full aft (airplane nose up) elevator control input, which aggravated the stall and spin.
<h2>There Is a History</h2>
According to NTSB, two other Hawker stall test flights were investigated. In each case, uncommanded roll behavior occurred on aircraft certified under Textron Aviation’s type certificate A3EU. The Hawker type certificate (A3EU), initially issued in the 1960s, has been held and transferred by at least seven different companies and includes 51 unique airplane models.
<h3>BAE 125-800A Incident in Nebraska</h3>
On May 4, 2006, a BAE 125-800A departed Lincoln, Nebraska (KLNK), for a manufacturer’s required post-maintenance stall test flight. During this flight test, according to the NTSB, the airplane entered a stall without the expected stick shaker and stick pusher activation and rolled uncommanded through 360 degrees. The pilot, copilot, and four technicians on board the aircraft sustained minor injuries. Both pilots were employed by the manufacturer; however, neither was a factory flight test pilot.
According to the flight crew, the stall test was conducted with the autopilot engaged, and the stall occurred at a higher airspeed than they had calculated. Unexpectedly, as the aircraft entered the stall, the right wing dropped abruptly, and the aircraft rolled through 360 degrees multiple times, both left and right. NTSB analysis of the flight data recorder indicated that the aircraft became inverted 4 seconds after the initial upset and lost 11,000 feet of altitude in 30 seconds. During the recovery, the crew and aircraft experienced downward acceleration forces that exceeded 6 g.
Again, investigators found that the flight crew initiated the stall test with ice contamination on the wings, and this contamination resulted in adverse stall behaviors. Although the flight crew did not observe any icing advisory lights or any ice on the wings, a technician on board saw “frost” on the wing surface near the root of the wing and reported it to the crew. The pilots continued with the stall test.
After this incident, Raytheon Aircraft issued an internal Production Flight Test Procedure that included a stall training syllabus that outlined the operational considerations for stall testing and clarified approved recovery procedures; this information was not included in the aircraft flight manual or pilot operating manual.
<h2>Incidents Involving Deformed Vortex Generators</h2>
On March 3, 2005, a Hawker 800XP undergoing a post-maintenance test flight in West Palm Beach, Florida, stalled without stick shaker or pusher activation and rolled three times to the right. During the recovery, the aircraft lost about 3,000 feet of altitude before the flight crew regained control of the aircraft.
Following this incident, maintenance personnel found several deformed vortex generators on the aircraft’s wing, which contributed to the unacceptable stall characteristics. The NTSB determined that a deformed vortex generator, inadequate fillet sealing on the wing leading edges, and additional imperfections may negatively impact Hawker stall performance.
An earlier stall test flight incident highlighted the adverse effects of deformed vortex generators. In 1993, a Hawker 125-800 exhibited unsatisfactory stall characteristics during a post-maintenance test flight. A Raytheon Service Information Leaflet (SER No. 180) reported that the aircraft entered an aerodynamic stall before the stick shaker or stick pusher and rolled uncommanded to the right. The leaflet advised operators of Hawker aircraft to exercise caution when cleaning the top surface of the wing and to replace or repair damaged vortex generators.
<h2>Hawker SME Discussion</h2>
The former factory test pilot, Grommet, inspected the condition and placement of the wing vortex generators before each stall test flight. “Unacceptable stall characteristics are remedied by adjustment of these spoilers (vortex generators),” according to Grommet. Each vortex generator can be moved by only .02 inches per adjustment. Grommet said they typically are adjusted during production test flights and, if maintained properly, the stall characteristics should never change.
During the NTSB interview, Grommet described his plan for a stall test flight. From the discussion, he took a disciplined approach to each of these flights using the same flight test procedure, test card, fuel loads, and briefings. Typically, Grommet flew for a block altitude of 14,000 feet msl to 16,000 feet msl and always stayed clear of icing conditions. He cautioned that flights above FL180 are undesirable because the true stall speed would increase due to the lower density of the air.
Grommet said, “99% of the time the test can be accomplished in 30 minutes.” During the test, he would stall and record the information on a test card using different flap and landing gear configurations. He always flew from the left seat and reviewed the stall test procedure with the other pilot on the ground. During the stall recovery, Grommet briefed the other pilot that “there would be more grass in the windscreen than they are used to.”
<h2>&nbsp;</h2>

<h2>NTSB Recommendations</h2>
As a result of its investigations, the NTSB made <a href="https://www.ntsb.gov/investigations/Pages/DCA26SR003.aspx">seven urgent safety recommendations</a>: five to Textron Aviation, the type certificate holder, and one each to the FAA and the NBAA.
The following recommendations were made to Textron Aviation:
Recommendation A-26-1: Define manufacturer-authorized pilot training and experience qualification criteria for pilots who perform post-maintenance stall test flights in Hawker 750, 800, 800XP, 850XP, and 900XP airplanes to ensure they are prepared with competencies needed to safely respond to an encounter with unacceptable stall characteristics.
Recommendation A-26-2: Develop a stall test plan that describes unacceptable stall characteristics, recovery procedures, and safety considerations needed to prepare manufacturer-authorized flight crewmembers to safely perform post-maintenance stall flight tests in Hawker 750, 800, 800XP, 850XP, and 900XP airplanes. &nbsp;&nbsp;
Recommendation A-26-3: Review all other models (besides the Hawker 750, 800, 800XP, 850XP and 900XP) listed on type certificate A3EU, and for each model that is subject to post-maintenance stall test flights, define stall test flight pilot training and experience qualification criteria and develop a stall test plan, as specified in Safety Recommendations A-26-1 and A-26-2 (above). &nbsp;
Recommendation A-26-4: Review the Pilot’s Operating Manual and Airplane Flight Manual for the airplanes on type certificate A3EU and revise them, as necessary, to provide a description of the adverse effects of certain wing surface anomalies, such as visually imperceptible defects or light ice accretion, on the airplane’s stall behavior, including:
<ul>
<li>
<ul>
<li>The possibility of stall before stick shaker or stick pusher activation;</li>
<li>A description of unacceptable stall characteristics; and</li>
<li>Procedures for recovering the airplane from an inadvertent encounter with a stall or adverse stall behavior.</li>
</ul>
</li>
</ul>
Recommendation A-26-5: Inform owners and operators of the airplane models on type certificate A3EU that are subject to post-maintenance stall flight tests of the circumstances of these accidents to increase their awareness of the possibility of unacceptable stall behavior, such as uncommanded roll through 360 degrees and entry into a spin, and that the flight crew training and experience needed to ensure the safety of these flights exceeds that which is typically provided to operational line pilots.
The following recommendation was made to the FAA:
Recommendation A-26-6: Require Textron Aviation to complete the actions specified in Safety Recommendations A-26-1 through A-26-3, and ensure that the information is accurate and correctly incorporated into the appropriate FAA-approved manual or document for each airplane.
The following recommendation was made to the NBAA:
Recommendation A-26-7: Inform your members about the recent accidents that occurred during post-maintenance stall flight tests required for certain Hawker airplanes including the Hawker 750, 800, 800XP, 850XP, 900XP, and others on type certificate A3EU, to increase owner, operator, and pilot awareness that unacceptable stall behavior may occur and that the flight crew training and experience needed to ensure the safety of these flights exceeds that which is typically provided to operational line pilots.

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