ATR-42 encounters wake turbulence from Boeing 737-300

Casualties unknown • Chicago, IL, US

An ATR-42 aircraft experienced significant vertical acceleration while on approach after encountering wake turbulence from a preceding Boeing 737-300.

What happened

While operating on the ILS 09R approach, an ATR-42 (Flight 146) encountered wake turbulence generated by a preceding Boeing 737-300 (Flight 554). At the time of the encounter, Flight 146 was positioned approximately 18 miles from the airport at an altitude of roughly 4,900 feet.

Radar data indicates that Flight 554 intercepted the localizer approximately 17.5 miles from the airport while descending through the altitudes of 5,200 feet to 4,800 feet. The separation between the two aircraft at the moment of the encounter was approximately 4.8 miles.

During the turbulence event, the ATR-42 experienced fluctuating vertical acceleration, which varied from a high of 2.3679 g's to a low of .5542 g's.

Probable cause

The encounter with wake turbulence produced by a preceding Boeing 737-300 while the ATR-42 was on approach.

Frequently asked questions

What happened in the 1998-09-18 Aerospatiale ATR-42-300 accident near Chicago, IL?

An ATR-42 aircraft experienced significant vertical acceleration while on approach after encountering wake turbulence from a preceding Boeing 737-300.

What aircraft was involved and where did it happen?

The accident on 1998-09-18 involved a Aerospatiale ATR-42-300, registration N233RM, operated by American Eagle, Inc., at Chicago, IL.

What was the probable cause of the accident?

The encounter with wake turbulence produced by a preceding Boeing 737-300 while the ATR-42 was on approach.

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