Investigation Summary
The MD-80 series uses a control tab system where the pilot's yoke moves a small tab on the elevator, which then uses aerodynamic force to move the larger elevator surface. Because these surfaces are not hydraulically powered, they are free to move when the aircraft is parked. During the two days N786TW was parked at Willow Run, a windstorm with gusts up to 55 knots affected the area. The aircraft was positioned downwind of a large hangar, which computational fluid dynamics (CFD) later showed created a 'canyon effect' of localized, vertical turbulence. This turbulence caused the right elevator to oscillate violently, eventually driving the geared tab linkage beyond its design limits until it locked overcenter. During the takeoff roll, the crew reached V1 and then Vr (rotation speed). When the captain pulled back on the yoke, the left elevator responded, but the jammed right elevator remained fixed in the full trailing-edge-down position, creating a massive nose-down moment that prevented the aircraft from lifting off. Recognizing the lack of pitch response, the captain called for an abort 12 seconds after V1. The aircraft overran the runway at approximately 100 knots, crossed a road, and came to rest in a field. The NTSB noted that the MD-83 design provided no way for the crew to detect a jammed elevator during standard pre-flight checks, as the tabs are not visible from the cockpit and the yoke remains free to move even if a surface is jammed. The airline operated four antiquated DC-9s, among fewer than 30 still in commercial service worldwide, and two MD-83s. Despite the severity of the overrun, everyone on board walked away from the accident, a miraculous outcome given the state of the aircraft.
Final Conclusions
The NTSB concluded that the probable cause was the jammed right elevator resulting from exposure to localized, dynamic wind while parked. The investigation highlighted that the wind speeds were below the manufacturer's 65-knot design limit for parked aircraft, but the presence of the hangar amplified the loads through turbulence. The board praised the captain's decision to reject the takeoff after V1, noting that although it violated standard high-speed abort protocols, continuing the takeoff in an un-flyable aircraft would have likely resulted in a catastrophic crash. The NTSB issued recommendations to Boeing and the FAA to develop methods for MD-80 crews to verify elevator freedom before takeoff.
Photographic Evidence (1)
Video Analysis
What STOPPED this Airplane from flying? | Air Crash Investigation — A detailed look at the Ameristar 9363 accident, explaining the unique MD-80 elevator system and how a windstorm jammed the controls.
If playback is blocked, the owner has disabled embedding — use the link above.
Crew Experience
Captain
Pilot Flying; Mark Radloff, 54, with 15,530 total flight hours.
Check Airman
Pilot Monitoring; Andreas Gruseus, 41, with 9,660 total flight hours.
Systems & Failure Modes
Elevator Control Tabs
A non-hydraulic system where the pilot moves a control tab, which then uses airflow to move the main elevator surface. This allows for manual control of large aircraft but leaves surfaces free to move in the wind when parked.
Geared Tab Linkage
A mechanical linkage that coordinates the movement of the elevator and its tabs. In this accident, the linkage was forced into an 'overcenter' position, locking the elevator.
Interesting Facts
- 01The aircraft was carrying the University of Michigan men's basketball team to the Big Ten tournament.
- 02The MD-80 series does not have a cockpit-controlled gust lock system for the elevators.
- 03The right elevator was jammed in a 15-degree trailing-edge-down position.
- 04The captain rejected the takeoff at a speed significantly higher than V1, which is normally prohibited.
- 05One emergency slide failed to inflate during the evacuation.
- 06The Michigan Wolverines went on to win the Big Ten tournament after traveling on a replacement flight the next day.
Safety Actions & Advisories
Elevator Inspection Requirements
The FAA issued Airworthiness Directives requiring MD-80 series operators to perform physical inspections of the elevator geared tab linkages following exposure to high winds.
Pre-flight Verification Procedures
Boeing was tasked with developing a procedure to allow flight crews to verify that elevators are not jammed before takeoff, such as observing tab movement during the flight control check.