Ameristar Charters Flight 9363 was a charter flight from
Willow Run Airport
Willow Run Airport is an airport in Van Buren Township, Michigan, Van Buren Charter Township and Ypsilanti Township, Michigan, Ypsilanti Charter Township, near Ypsilanti, Michigan, Ypsilanti, Michigan, United States, that serves freight, cor ...
to
Washington Dulles Airport
Washington Dulles International Airport ( ) – commonly known by its former name of Dulles International Airport, by its airport code of IAD, or simply as Dulles Airport – is an international airport in the Eastern United States, located w ...
on March 8, 2017, which
rejected takeoff
In aviation, a rejected takeoff (RTO) or aborted takeoff is the situation in which the pilot decides to abort the takeoff of an airplane after initiating the takeoff roll but before the airplane leaves the ground.
Reasons to perform a rejected ta ...
and
overran the runway. The crash was caused by a jammed
elevator
An elevator (American English) or lift (Commonwealth English) is a machine that vertically transports people or freight between levels. They are typically powered by electric motors that drive traction cables and counterweight systems suc ...
, which was damaged by high winds the day before the crash.
All 116 passengers and crew survived the crash, with only one minor injury, but the aircraft was
damaged beyond repair. The
NTSB
The National Transportation Safety Board (NTSB) is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and inc ...
investigation found that the elevator was damaged while the aircraft was parked, and then was not noticed due to flaws in the aircraft's design and Ameristar's operating procedures.
Accident
The aircraft had been chartered to transport the
Michigan Wolverines men's basketball
The Michigan Wolverines men's basketball team is the College basketball, intercollegiate men's basketball program representing the University of Michigan. The school competes in the Big Ten Conference in NCAA Division I, Division I of the Nationa ...
team to the
Big Ten tournament Big Ten Tournament can refer to any Big Ten Conference sport that has a tournament or championship game:
* Big Ten Football Championship Game
* Big Ten men's basketball tournament
* Big Ten women's basketball tournament
* Big Ten baseball tournamen ...
in
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with ...
for the following day's game against the
Illinois Fighting Illini
The Illinois Fighting Illini () are the College athletics, intercollegiate athletic teams that represent the University of Illinois Urbana-Champaign. The university offers 10 men's and 11 women's Varsity team, varsity sports.
The university op ...
.
Prior to the flight, the aircraft had been parked at Willow Run Airport since it arrived from
Lincoln Airport in
Lincoln, Nebraska
Lincoln is the List of capitals in the United States, capital city of the U.S. state of Nebraska. The city covers and had a population of 291,082 as of the 2020 census. It is the state's List of cities in Nebraska, second-most populous city a ...
on March 6.
Hours before the accident, the
air traffic control tower
Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled ai ...
at Willow Run Airport had been evacuated due to high winds.
The windstorm affected much of
Southeast Michigan
Southeast Michigan, also called southeastern Michigan, is a region in the Lower Peninsula of Michigan that is home to a majority of the state's businesses and industries as well as slightly over half of the state's population, most of whom are c ...
,
and resulted in power outages for over 800,000
DTE customers. A power outage at Willow Run disabled most of the weather instrumentation in the airport's
automated surface observing system
Airport weather stations are automated sensor suites which are designed to serve aviation and meteorological operations, weather forecasting and climatology. Automated airport weather stations have become part of the backbone of weather observing ...
(ASOS), and manual weather observations were also unavailable due to the evacuation of the control tower.
As a result, the flight crew of Flight 9363 obtained weather information from alternate sources, contacting company operations personnel for a temperature setting, and calling the nearby
Detroit Metropolitan Airport
Detroit Metropolitan Wayne County Airport is the primary international airport serving Detroit and its Metro Detroit, surrounding metropolitan area, in the U.S. state of Michigan. It is located in Romulus, Michigan, Romulus, a Detroit suburb ...
on one of the pilots'
cell phone
A mobile phone or cell phone is a portable telephone that allows users to make and receive calls over a radio frequency link while moving within a designated telephone service area, unlike fixed-location phones ( landline phones). This radio ...
s to get the current weather information at the latter airport. Lacking information from the ASOS, the crew used
windsock
A windsock (also known as wind cone or wind sleeve) is a conical textile tube that resembles a giant sock. It can be used as a basic indicator of wind speed and direction, or as decoration. Windsocks are typically used at airports to show the d ...
s at the airport to determine the predominant wind direction and inform their choice of runway.
The flight crew modified their planned takeoff to protect against the danger of
wind shear
Wind shear (; also written windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical ...
, selecting a higher
rotation
Rotation or rotational/rotary motion is the circular movement of an object around a central line, known as an ''axis of rotation''. A plane figure can rotate in either a clockwise or counterclockwise sense around a perpendicular axis intersect ...
speed than would otherwise be prescribed.
The flight was delayed slightly, due to the communication difficulties caused by the power outages at the airport.
Flight 9363 taxied uneventfully to runway 23L, and received its takeoff clearance from Detroit Metropolitan via cell phone due to the lack of ATC services at Willow Run. The
check airman
A check pilot (or check airman) is an aircraft pilot who performs an oversight, safety, and qualification role for commercial pilots undergoing evaluation. The role of the check pilot is to ensure that the flight crew member has met competency st ...
acting as
pilot in command
The pilot in command (PIC) of an aircraft is the person aboard an aircraft who is ultimately responsible for its operation and safety during flight. This would be the captain in a typical two- or three- pilot aircrew, or "pilot" if there is only ...
, 41-year-old Andreas Gruseus, directed the
captain
Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader or highest rank officer of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police depa ...
, 54-year-old Mark Radloff,
to begin the takeoff roll, which began at 14:51:12
EST.
The takeoff roll was normal until rotation speed (
VR), at
indicated airspeed
Indicated airspeed (IAS) is the airspeed of an aircraft as measured by its pitot-static system and displayed by the airspeed indicator (ASI). This is the pilots' primary airspeed reference.
This value is not corrected for installation error, ...
(KIAS). At V
R, when the captain pulled back on the
control column
A yoke, alternatively known as a control wheel or a control column, is a device used for Pilot (aeronautics), piloting some fixed-wing aircraft.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 563. Aviation Supplies ...
to rotate the aircraft, the aircraft failed to respond, even after the captain applied additional back force to the control column. Judging the aircraft to be incapable of flight, the captain performed a
rejected takeoff
In aviation, a rejected takeoff (RTO) or aborted takeoff is the situation in which the pilot decides to abort the takeoff of an airplane after initiating the takeoff roll but before the airplane leaves the ground.
Reasons to perform a rejected ta ...
, immediately applying maximum braking followed by
spoiler
Spoiler or Spoilers may refer to:
Arts, entertainment and media
* Spoiler (media), something that reveals significant plot elements
* The Spoiler, DC Comics superheroine Stephanie Brown
Film and television
* ''Spoiler'' (film), 1998 American ...
s and
reverse thrust Reverse or reversing may refer to:
Arts and media
*Reverse (Eldritch album), ''Reverse'' (Eldritch album), 2001
*Reverse (2009 film), ''Reverse'' (2009 film), a Polish comedy-drama film
*Reverse (2019 film), ''Reverse'' (2019 film), an Iranian cr ...
.
By the time the captain rejected the takeoff, the aircraft had accelerated to , over above the decision speed (
V1), and was moving too fast to stop in the remaining runway distance. The aircraft ran off the end of the runway and across the grassy
runway safety area
A runway safety area (RSA) or runway end safety area (RESA, if at the end of the runway) is defined as "the surface surrounding the runway prepared or suitable for reducing the risk of damage to airplanes in the event of an undershoot, overshoot, ...
(RSA), before striking the raised pavement of an access road along the airport perimeter.
Upon striking the road pavement, the aircraft's
landing gear
Landing gear is the undercarriage of an aircraft or spacecraft that is used for taxiing, takeoff or landing. For aircraft, it is generally needed for all three of these. It was also formerly called ''alighting gear'' by some manufacturers, s ...
collapsed, and the aircraft slid on its belly over the road and a ditch just beyond, causing substantial damage to the belly and underside of the nose. The aircraft came to a stop with its
empennage
The empennage ( or ), also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow.Crane, Dale: ''Dictionary of Aeronautical Terms, third ed ...
on the road and its nose in a grassy field on the far side of the road and ditch.
An orderly, rapid evacuation followed. The aircraft had 8 emergency exits, of which 4 were used. One emergency exit was rendered unusable by a faulty
evacuation slide
An evacuation slide is an inflatable slide used to evacuate an aircraft quickly. An escape slide is required on all commercial (passenger carrying) aircraft where the door sill height is such that, in the event of an evacuation, passengers would ...
, and another was blocked by a seatbelt stuck in the door. All 110 passengers and 6 crew members survived the crash, with one injury, a passenger who suffered a laceration to the leg.
Aircraft
The aircraft involved was a
McDonnell Douglas MD-83 (DC-9-83), registration N786TW, manufacturer serial number (MSN) 53123, line number 1987. It was damaged beyond repair in the accident and written off aged 25 years.
Investigation
Aircraft design
The crash occurred after the aircraft failed to rotate upwards, and the investigation focused on the aircraft's elevator system as a cause of the failure. The elevators of the MD-80 series aircraft are controlled indirectly via a system of
servo tab
A servo tab is a small hinged device installed on an aircraft control surface to assist the movement of the Flight control surfaces, control surfaces. Introduced by the German firm Flettner, servo tabs were formerly known as Flettner tabs. Ser ...
s, using a design similar to the MD-80's predecessor, the
DC-9
The McDonnell Douglas DC-9 is an American five-abreast, single-aisle aircraft designed by the Douglas Aircraft Company. It was initially produced as the Douglas DC-9 prior to August 1967, after which point the company had merged with McDonnell A ...
.

During a normal takeoff in an MD-80 aircraft, the pilot rotates the aircraft off the runway by pulling the
control column
A yoke, alternatively known as a control wheel or a control column, is a device used for Pilot (aeronautics), piloting some fixed-wing aircraft.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 563. Aviation Supplies ...
back (aft), which moves the elevator control tab into a trailing-edge-down (TED) position. The elevator control tab directs airflow around the elevator, and causes
lift
Lift or LIFT may refer to:
Physical devices
* Elevator, or lift, a device used for raising and lowering people or goods
** Paternoster lift, a type of lift using a continuous chain of cars which do not stop
** Patient lift, or Hoyer lift, mobile ...
from forward airflow to move the elevators in the opposite direction of the tab. The elevator is in turn linked to two more servo tabs, including a geared tab that provides
mechanical advantage
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to obtain a desired amplification in the output force. The model for ...
to the pilot's control inputs. During takeoff, the pilot's commands through the control column, via the system of three servo tabs, ultimately moves the elevator into a
trailing-edge-up (TEU) position. This affects the
pitch angle of the aircraft, and rotates it up and off the runway.
As a consequence of this design, the elevators are not able to be moved during a typical preflight inspection, when the aircraft is stationary and there is no airflow over the elevators. A more thorough inspection of the elevators involves moving them by hand, but it requires a
scissor lift
An aerial work platform (AWP), also an aerial device, aerial lift, boom lift, bucket truck, cherry picker, elevating work platform (EWP), mobile elevating work platform (MEWP), or scissor lift, is a mechanical device used to provide temporary ...
(or similar equipment) to reach the top of the
T-tail
A T-tail is an empennage wikt:configuration, configuration in which the tailplane of an aircraft is mounted to the top of the vertical stabilizer, fin. The arrangement looks like the capital letter T, hence the name. The T-tail differs fr ...
in the air, and is not typically performed during a preflight inspection.
Another consequence of the elevator system design is that when the aircraft is parked, the elevators move freely with the wind, within limits. The MD-80 is not equipped with a
gust lock
A gust lock on an aircraft is a mechanism that locks control surfaces and keeps open aircraft doors in place while the aircraft is parked on the ground and non-operational. Gust locks prevent wind from causing unexpected movements of the contro ...
, which would prevent this motion. The range of motion of the elevator is constrained by stops, which are equipped with
shock absorber
A shock absorber or damper is a mechanical or hydraulics, hydraulic device designed to absorb and Damping ratio, damp shock (mechanics), shock impulses. It does this by converting the kinetic energy of the shock into another form of energy (typic ...
s for protection. This system is designed to withstand high-speed airflow from straight ahead during flight, but strong forces from other directions can overcome the shock absorbers. If the linkages in the geared tab move too far, they can become "overcentered," jamming the elevator in place. The MD-80 was designed to withstand horizontal wind gusts of up to from any direction while on the ground.
Postaccident condition of the control systems
When the aircraft was inspected on site following the accident, the right elevator was found to be jammed in a full trailing-edge-down (TED) position slightly beyond its normal limit of motion, and could not be moved by hand.
The inboard control linkage of the right elevator's geared tab was damaged, being locked in an overcenter position, beyond its normal limit of travel, and with portions of the control linkage bent and displaced outboard.
When the damaged linkage was disconnected by investigators, the elevator could be freely moved by hand from stop to stop.
The cockpit controls could be moved throughout their full range of motion, and the control tabs were observed to move properly in response to control column inputs.
Company policies and maintenance
Ameristar's procedures were intended to protect aircraft from damage to flight controls from high winds. Per company policy, aircraft stored outside in winds of over 60 knots had to be parked facing into the wind. If aircraft had been exposed to wind gusts in excess of 65 knots from other than straight ahead while parked, a physical inspection of all flight control surfaces would have been required, including a check confirming that the control surfaces were free to move.
Measurement equipment at Willow Run recorded maximum wind gusts of , below both thresholds.
A review of elevator-position data from the aircraft's
flight data recorder
A flight recorder is an electronic recording device placed in an aircraft for the purpose of facilitating the investigation of aviation accidents and incidents. The device may often be referred to colloquially as a "black box", an outdated nam ...
(FDR) showed that the right elevator moved properly on the morning of March 6, during a maintenance check.
By the next time the aircraft was powered up, at 12:38 on the day of the accident, the right elevator was already at the full trailing-edge-down position, and remained there in all elevator-position data recorded during the preparations for the flight to Dulles.
In contrast, the left elevator moved several times throughout its full range of motion under the influence of ground winds.
During the attempted takeoff, the left elevator followed the captain's commands, but the right elevator remained in the full trailing-edge-down position until partway through the attempted rotation, and then only moved slightly.
Prior elevator jam incident (Munich, 1999)
Prior to the Flight 9363 accident, the aircraft manufacturer had record of only one wind-induced elevator jam on any DC-9-series aircraft, which occurred at
Munich Airport, Germany, in December 1999, and involved exposure to winds exceeding the elevator system's design limits.
In that incident, the airport had been subjected to a severe windstorm while the incident aircraft (another MD-83) was on the ground, with peak winds of up to . This exceeded the manufacturer's mandatory inspection limits for the DC-9/MD-80 flight control system, and the flight crew requested an inspection of the aircraft's flight control system.
A full inspection of the aircraft's elevators, which would have involved moving the elevators by hand, was not conducted due to personnel-safety concerns in the continuing high winds. Instead, maintenance personnel had the flight crew perform a flight control check by moving the control column throughout its entire range of motion and checking for any abnormal resistance.
No abnormalities were detected during this check, and the aircraft was released for flight. The aircraft was unable to rotate off the runway, and the flight crew were forced to reject the takeoff at very high speed. In this instance, the aircraft was safely brought to a stop on the runway.
The
(BFU) found that the Munich aircraft's left elevator was jammed in a full trailing-edge-down position, having been forced into that position by the high winds experienced on the ground.
Boeing, as recommended by the BFU, instituted new procedures for DC-9, MD-80, and Boeing 717 operators, requiring inspections of elevator systems after aircraft were exposed to high winds on the ground. The threshold set was without the aircraft's nose pointed into the wind, and the requirements following exposure to winds below this threshold remained unchanged.
Wind field analysis and load testing of elevator system

The aircraft in the Ameristar 9363 incident was damaged in the same way as the aircraft in Munich, but it was not subject to winds nearly as strong. Investigators identified a
hangar
A hangar is a building or structure designed to hold aircraft or spacecraft. Hangars are built of metal, wood, or concrete. The word ''hangar'' comes from Middle French ''hanghart'' ("enclosure near a house"), of Germanic origin, from Frankish ...
immediately upwind of the aircraft's parking position as a potential cause of wind conditions that could have affected the aircraft. The investigators performed
computational fluid dynamics
Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid dynamics, fluid flows. Computers are used to perform the calculations required ...
(CFD) modeling of the wind field downwind of the hangar and around the parked aircraft, using a detailed three-dimensional model of the hangar obtained via
drone
Drone or The Drones may refer to:
Science and technology Vehicle
* Drone, a type of uncrewed vehicle, a class of robot
** Unmanned aerial vehicle or aerial drone
*** Unmanned combat aerial vehicle
** Unmanned ground vehicle or ground drone
** Unma ...
imagery.
The CFD analysis showed that the hangar had a significant impact on the local winds at the parked aircraft. A horizontal gust passing over the hangar was found to produce a 58-knot gust at the aircraft itself. The hangar also introduced significant turbulence, which produced vertical forces. These forces could slam the aircraft's elevators forcefully between their stops, potentially resulting in flight-control damage.
To determine whether this theory was possible, the NTSB performed a series of static and dynamic load tests on the accident aircraft's undamaged horizontal stabilizers and left elevator. The tests, conducted at a Boeing laboratory in
Huntington Beach, California
Huntington Beach is a seaside city in Orange County, California, United States. The city was originally called Pacific City, but it was changed in 1903 to be named after American businessman Henry E. Huntington. The population was 198,711 as of ...
, simulated the wind conditions calculated by the CFD analysis. The static tests consisted of hanging weights from the elevator while in its trailing-edge-down position, simulating constant wind speeds. Static testing resulted in no damage to the geared tab linkage (the damaged component of the accident aircraft), even at wind speeds of up to .
The dynamic load tests simulated
turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to laminar flow, which occurs when a fluid flows in parallel layers with no disruption between ...
in the wind flow by lifting the elevator and dropping it. The investigators used the same quantity of weight as the static tests, simulating the same horizontal wind speeds with more fluctuation of vertical wind speed. A simulated 60-knot gust applied to the elevator in its full trailing-edge-up position, slamming down to its full TED position, was sufficient to overcenter the geared tab linkage. A simulated 70-knot gust was able to achieve similar effects from the elevator's neutral position.
As a final test, with the inboard geared-tab linkage of the test elevator locked in an overcenter position, a TEU force was applied to the elevator using the forklift, simulating the conditions during the takeoff roll. The overcentered links failed and bent outboard, in the same manner as the right elevator did during the takeoff roll.
Probable cause
The NTSB released their final report in February 2019,
which concluded that
Pilots' actions
The report praised the actions of the flight crew for contributing to the lack of serious injuries or fatalities in the accident.
In a press release on March 7th, 2019, NTSB chairman
Robert Sumwalt stated "This is the kind of extreme scenario that most pilots never encounter – discovering that their plane won't fly only after they know they won't be able to stop it on the available runway. These two pilots did everything right after things started to go very wrong."
Aftermath
The morning after the crash, the Wolverines men's basketball team traveled to Washington on the
Detroit Pistons
The Detroit Pistons are an American professional basketball team based in Detroit. The Pistons compete in the National Basketball Association (NBA) as a member of the Central Division (NBA), Central Division of the Eastern Conference (NBA), East ...
team plane.
The team arrived at the
Verizon Center in Washington at 10:30 AM, in time for their noon game against
Illinois
Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. It borders on Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash River, Wabash and Ohio River, Ohio rivers to its ...
. The Wolverines played the game in their practice uniforms, as the team's luggage was still on the crashed plane. The Wolverines won against Illinois, 7555, and went on to win the
Big Ten tournament Big Ten Tournament can refer to any Big Ten Conference sport that has a tournament or championship game:
* Big Ten Football Championship Game
* Big Ten men's basketball tournament
* Big Ten women's basketball tournament
* Big Ten baseball tournamen ...
. Following their Big Ten tournament victory, the Wolverines advanced in the
NCAA tournament, reaching the Sweet Sixteen round before losing to
Oregon
Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...
on March 24.
Legacy
In response to the crash, Boeing developed a modification to the DC-9 elevator system, which would add a second stop to the elevator system. This secondary stop would physically prevent the elevator from moving far enough past its limits to allow the geared-tab linkages to become locked in an overcenter configuration. For DC-9s with tab-driven elevators not yet equipped with the secondary elevator stop, including DC-9s, MD-80s, and 717s, the maintenance manual was revised to decrease the wind strengths which would necessitate a physical inspection of the elevator system before further flight.
The NTSB recommended that Boeing finalize and fully implement these changes, and also develop a means for DC-9 flight crews to detect an elevator jam before attempting to take off.
See also
*
2021 Houston MD-87 crash, an MD-80 runway excursion that resulted in the total destruction of the aircraft due to flight-control damage similar to Flight 9363
Notes
References
External links
* NTSB accident report
summaryPDF
NTSB investigation docketarchive
Accident descriptionat the
Aviation Safety Network
The Flight Safety Foundation (FSF) is a non-profit, international organization concerning research, education, advocacy, and communications in the field of aviation safety. FSF brings together aviation professionals to help solve safety problems ...
archive
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Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...