Boeing B-737-300 accident near Aliquippa, Pennsylvania, September 8, 1994
On September 8, 1994 at about 11:03 pm local time, a Boeing B-737-300, registered N513AU, was destroyed in an accident near Aliquippa, Pennsylvania. It was a flight of an unrecorded kind under scheduled airline rules (Part 121). 132 people were killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A loss of control of the airplane resulting from the movement of the rudder surface to its blowdown limit. The rudder surface most likely deflected in a direction opposite to that commanded by the pilots as a result of a jam of the main rudder power control unit servo valve secondary slide to the servo valve housing offset from its neutral position and overtravel of the primary slide.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 8, 1994 · about 11:03 pm local time
- Place
- Aliquippa, Pennsylvania · map
- Type
- Accident
- Injuries
- 132 people were killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Boeing B-737-300
- Registration
- N513AU · no longer on the register · serial 24549
- Damage
- Destroyed
- Flight
- Flight of an unrecorded kind · scheduled airline rules (Part 121)
The NTSB's narrative final · quoted from the NTSB record
The airplane crashed while maneuvering to land at Pittsburgh International Airport. The airplane entered an uncontrolled descent and impacted terrain about 6 miles east of the airport. The airplane struck the ground at an angle of descent of about 80 degrees, in a slight roll to the left, and the airspeed was about 260 knots at impact. The investigation revealed that during the accident sequence, the airplane rudder deflected rapidly to the left and reached its left aerodynamic blowdown limit shortly thereafter. Examination of the rudder system revealed that it is possible, in the main rudder power control unit (PCU) of the airplane (as a result of some combination of tight clearances within the servo valve, thermal effects, particulate matter in the hydraulic fluid, or other unknown factors), the servo valve secondary slide could jam to the servo valve housing at a position offset from its neutral position without leaving any obvious physical evidence and that, combined with rudder pedal input, could have caused the rudder to move opposite to the direction commanded by a rudder pedal input. This condition of the PCU was also consistent with analysis of the cockpit voice recorder, computer simulation, and human performance data, including operational factors
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot, commercial pilot, flight engineer
- Ratings: multi-engine land; instrument: airplane
- Flight time: 12,000 hours in all; 12,381 in this make and model; 112 in the last 90 days; 20 in the last 30 days
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 23,846 hours
- Last inspection: continuous airworthiness programme, August 8, 1994; 274 hours since
- Maximum gross weight: 142,500 lb
- Seats: 142
- Landing gear: retractable
- Engine: Cfm CFM65-3-B2/1 (turbofan); 0 hours total
- Fire on the ground
The flight
- Departed from: ORD Chicago IL at 11:30 pm
- Destination: PIT Pittsburg PA
- Flight plan: IFR
- Runway 0
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: at 0 knots
- Visibility: 15 statute miles
- Sky: not recorded; scat at 8,000 ft
- Temperature: 73°F (23°C), dew point 52°F (11°C)
- Altimeter: 30.00 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 5 | |||
| Passengers | 127 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.