# Accident 19980917046359A: Aerosp ATR42300, Chicago, IL, September 17, 1998

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: September 17, 1998, 19:33 local time
- Place: Chicago, IL
- Airport: Chicago-O Hare International
- Phase of flight: Initial Approach-IFR
- Operating rules: Air carrier (Part 121)
- Operator: SIMA
- Location: 41.9628° N, 88.2580° W: Placed by OpenAirDocs from the FAA’s distance and direction from , within about 5 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=41.9628&lon=-88.2580&mi=10
- Aircraft: N233RM, a cancelled registration (https://openairdocs.org/deregistered/N233RM-2006-09-22) (OpenAirDocs)
- Registry model: Aerospatiale/Aeritalia ATR 42-300 (registry code 8680920, https://openairdocs.org/model/aerospatiale-aeritalia-atr-42-300) (OpenAirDocs)
- Registry engine: Pratt & Whitney Canada PW120 (registry code 52114, https://openairdocs.org/engine/pratt-whitney-canada-pw120) (OpenAirDocs)
- Reported make and model: AEROSP ATR42300
- Reported engine: PWA PW120
- People aboard: 15
- Fatal injuries: 0
- Pilot flight hours: 9,296 total, 3,621 in this make and model, 178 in the last 90 days
- NTSB investigation: [NTSB CHI98LA351](https://openairdocs.org/ntsb/CHI98LA351) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/19980917046359A

## Narrative

As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^.

(.4)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.      (-23) ON SEPTEMBER 17, 1998, AT 1954 CENTRAL DAYLIGHT TIME (CDT), AN ATR-42, OPERATED BY AMERICAN EAGLE (SIMA), AS FLIGHT #4146, ENCOUNTERED MODERATE WAKE TURBULENCE FROM A BOEING 737. THE FLIGHT WAS 20 MILES OUT ON APPROACH TO O'HARE INTERNATIONAL AIRPORT.  THE AIRCRAFT WAS NOT DAMAGED.  NO PASSENGERS RECEIVED ANY INJURIES.  THE FLIGHT ATTENDANT RECEIVED A FRACTURED ANKLE.  TWO COCKPIT CREWMEMBERS WERE NOT INJURED.

## The NTSB's investigation of this event (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB CHI98LA351](https://openairdocs.org/ntsb/CHI98LA351), Sep 18, 1998: Aerospatiale ATR-42-300 (N233RM), Chicago, IL, no damage. Probable cause: the wake turbulence encountered by Flight 146.

From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record.

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