Aerospatiale ATR-42-300 accident near Chicago, Illinois, September 18, 1998
On September 18, 1998, a Aerospatiale ATR-42-300, registered N233RM, was involved in an accident near Chicago, Illinois (O'Hare Int'L airport). It was a flight of an unrecorded kind under scheduled airline rules (Part 121). 1 person was seriously injured; 15 others were unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
the wake turbulence encountered by Flight 146.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 18, 1998
- Place
- Chicago, Illinois · O'Hare Int'L
- Type
- Accident
- Injuries
- 1 person was seriously injured; 15 others were unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Aerospatiale ATR-42-300
- Registration
- N233RM · no longer on the register · serial 235
- Damage
- Not recorded
- Flight
- Flight of an unrecorded kind · scheduled airline rules (Part 121)
The NTSB's narrative final · quoted from the NTSB record
Flight 146, an ATR-42 was approximately 18 miles from the airport on the ILS 09R approach when it encountered wake turbulence from a Flight 554, a Boeing 737-300, which was vectored onto the approach from the north in front of Flight 146. Radar data showed Flight 554 intercepted the localizer approximately 17.5 miles from the airport while descending from 5,200 feet to 4,800 feet. Flight 146 was at an altitude of about 4,900 feet when the wake turbulence encounter occurred. Separation of the two airplanes when the encounter occurred was approximately 4.8 miles. Vertical acceleration of Flight 146 varied from 2.3679 g's to .5542 g's during the encounter.
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
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 9,296 hours in all; 3,621 in this make and model; 178 in the last 90 days; 61 in the last 30 days; 7,725 as pilot in command; 662 on instruments
- Medical certificate: Class 1 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Last inspection: approved inspection programme, June 6, 1997
- Maximum gross weight: 37,258 lb
- Seats: 49
- Landing gear: retractable
- Engine: P&W PW 120 (turboprop); 0 hours total
- Operator: American Eagle, INC.
The flight
- Departed from: CWA Mosinee WI at 11:36 pm
- Destination: ORD
- Flight plan: IFR
- Runway 0
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 040° at 10 knots
- Visibility: 10 statute miles
- Sky: scat at 8,000 ft
- Temperature: 72°F (22°C), dew point 10°F (-12°C)
- Altimeter: 30.00 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | 2 | ||
| Passengers | 13 |
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.