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Stall tests are an action item for an airplane returning to service after certain wing repairs. Safety first is the goal, but when a flight test goes awry and ends in fatalities, it begets the question of the process in the first place. On February 7, 2024, a Hawker 900XP on a test flight crashed in Westwater, Utah, caught fire, and was completely destroyed. Two flight crew members were killed. Following its investigation, the National Transportation Safety Board (NTSB) issued its Final Accident Report on December 23, 2025. The NTSB detailed the accident's probable causes and issued urgent safety recommendations to Textron Aviation (then the Hawker type certificate holder), the Federal Aviation Administration (FAA), and the National Business Aviation Association (NBAA).Accident overviewOn December 20, 2023, a Hawker 900XP (N900VA) underwent routine maintenance at West Star Aviation's Grand Junction, Colorado maintenance facility. Located at the Grand Junction Regional Airport, the facility had performed multiple routine inspections on the subject aircraft. The maintenance tasks included a requirement to remove the wing's leading edges and TKS panels. Maintenance personnel searched for cracks and evidence of corrosion. Following the inspections' completion, the Hawker 900XP was returned to service on February 6, 2024.On February 7, 2024, the Hawker's flight crew began executing a post-maintenance stall warning and systems check-in soon after leaving Grand Junction Regional Airport. The flight was en route to Gig Harbor, Washington. The airframe manufacturer required this post-maintenance procedure, which integrated exacting criteria for the flight environment, meteorological conditions, and aircraft equipment settings. The aircraft unexpectedly began a rapid corkscrew-shaped descent as the Hawker 900XP spiraled into remote terrain near the Utah-Colorado border. The pilot in command (PIC) and second in command (SIC) were killed and the aircraft was consumed by the post-crash fire.The NTSB provided a Project Summary of 33 docket items related to the Hawker 900XP crash (Accident Number WPR24FA083). The Project Summary was released to the public on December 23, 2025, according to the NTSB.The flight crew's stall test trainingDuring the year before the accident, both flight crew members attended a commercial facility's simulator training sessions. The PIC received recurrent training while the SIC received initial training. They did not attend the sessions together.The training sessions detailed the stall warning and identification system (shaker and pusher) operation with a focus on recognizing and avoiding stall situations. The simulator-based training was not structured to teach full stalls or prepare crew members for a potential uncommanded roll.The accident flight's PIC took part in a stall test flight four years before the accident. However, as SIC at the time, he likely had limited test involvement. The flight's SIC had not been a stall test flight participant prior to the accident flight.Therefore, the NTSB determined that the flight crew's stall warning and identification system simulator training, and the PIC's earlier stall test flight participation, likely did not adequately prepare them to safely execute a stall test flight. Further, the NTSB said the training did not prepare the flight crew to address unacceptable stall behavior, according to the NTSB's Final Accident Report.The accident's probable causes After a thorough investigation, the NTSB determined that the Hawker 900XP accident had two probable causes and one significant contributing factor. First, the NTSB cited the flight crew's decision to conduct the post-maintenance stall test during icing conditions. This operating environment led to wing contamination that substantially reduced the aircraft's critical angle of attack.Additionally, the NTSB said the aircraft manufacturer had not established training and experience requirements that could enable the flight crew to safely complete the stall test. Lacking this framework, the crew attempted a remedial action that magnified the aerodynamic stall. This led to the flight crew's loss of control from which they could not recover the airplane.The accident's contributing factor For the contributing factor, the NTSB said the Hawker 900XP's flight crew did not adhere to established stall test conditions. These criteria pertained to the cloud clearance, visual meteorological conditions, and the altitude limit. The flight crew also did not ensure that all aircraft external surfaces were ice-free.An airport security camera video taken before the accident flight's departure displayed low-altitude cloud cover around the airport. While observing the accident flight crew's pre-flight inspection, a maintenance facility mechanic noted that precipitation and sleet were present, according to the NTSB's Final Accident Report.The NTSB's recommendationsFollowing the NTSB's investigation, the agency identified discrepancies in information accessible to airplane owners, pilots, and operators. This information pertained to safe performance of manufacturer-required post-maintenance stall test flights in specific Hawker aircraft models. The NTSB said that because of these training and procedural deficiencies, other flight crews assigned to execute such flights could also be unprepared for safe performance. That risk wasn't hypothetical. On October 16, 2025, a Hawker 800XP, XA-JMR, crashed near Battle Creek, Michigan, during its own post-maintenance stall test, after the same category of wing leading-edge and TKS panel work performed on N900VA. The pilot, copilot, and a maintenance representative aboard were killed. According to Duncan Aviation, the flight crew could not coordinate with a test pilot and conducted the stall test on their own. The NTSB has not yet issued a final report or probable cause finding on that crash, but the preliminary findings, and their resemblance to the Westwater crash, are likely what turned what may have been a routine NTSB recommendation into an urgent one.Therefore, the NTSB issued the following urgent safety recommendations. These recommendations were contained in a separate NTSB safety recommendation action (DCA26SR003) which was adopted on January 2, 2026.Urgent safety recommendations to Textron AviationSpecify manufacturer-authorized pilot training and experience qualification criteria for pilots performing post-maintenance stall test flights in certain Hawker airplanes (A-26-1).Create a stall test plan, ideally preparing manufacturer-authorized flight crew members to safely execute post-maintenance stall test flights in certain Hawker airplanes (A-26-2).Review all other type certificate A3EU airplane models. For models subject to post-maintenance stall test flights, Textron Aviation should specify stall test flight pilot training and experience qualification requirements and create a stall test plan (A-26-3). Review the Pilot's Operating Manual and Airplane Flight Manual for type certificate A3EU airplane models. Textron Aviation should revise the manuals as needed to describe the adverse effects of specific wing surface anomalies on the aircraft's stall behavior (A-26-4). Notify owners and operators of type certificate A3EU airplane models with post-maintenance stall test flight requirements of the accident's circumstances. The flight crew's training and experience necessary to ensure the flight's safety should exceed that typically given to operational line pilots (A-26-5). Urgent safety recommendation to the FAAThe NTSB said the FAA should require Textron Aviation to execute the actions detailed in Safety Recommendations A-26-1 through -3. Further, Textron Aviation must ensure the integration of accurate information into the proper FAA-approved document or manual for each aircraft (A-26-6). Urgent safety recommendation to the NBAA The NTSB said that the National Business Aviation Association (NBAA) should make the organization's members aware of recent accidents related to required post-maintenance stall flight tests. The requirement applies to Hawker 750, 800, 800XP, 850XP, and 900XP business jets. The post-maintenance stall flight test requirement also applies to other type certificate A3EU aircraft.The NTSB seeks to heighten owner, pilot, and operator awareness of unacceptable stall behavior's occurrence. The NTSB said the flight crew's training and experience necessary to ensure the subject flight's safety should go beyond that typically furnished to operational line pilots (A-26-7). Broader stall test scrutinyThe takeaway for Hawker operators is clear after two fatal accidents in the same test regime. Test flight training and procedures need immediate remediation. But this is also a moment for other manufacturers, along with business jet owners and operators to consider a review of post-maintenance stall flight test requirements and flight crew training and experience criteria.