# NTSB CHI93LA224: Boeing 757-222, N579UA, Baraboo, WI, June 24, 1993

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: June 24, 1993, 12:29 local (17:29 UTC)
- Place: Baraboo, WI
- Coordinates: 43.45932, -89.739662 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=43.4593&lon=-89.7397&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious, 147 uninjured
- Status: Completed, report August 17, 1994
- Report: Approved by Office Director
- NTSB case key (mKey): 9226
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI93LA224
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/9226/pdf
- Page: https://openairdocs.org/ntsb/CHI93LA224

## Probable cause

an encounter with moderate turbulence in the clouds.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Altitude deviation,uncontrolled, descent - normal
  - weather condition - turbulence in clouds (cause)

## Analysis

THE AIRPLANE WAS DESCENDING ON A VECTOR FOR LANDING ON RUNWAY 14R AT CHICAGO O'HARE INTERNATIONAL AIRPORT. PASSING THROUGH FLIGHT LEVEL 290 THERE WAS A SHORT ENCOUNTER WITH MODERATE TURBULENCE WHILE STILL IN THE CLOUDS. ONE FLIGHT ATTENDANT FELL AND INJURED HER ANKLE DURING THE ENCOUNTER. WHEN SHE WAS TREATED FOR THE INJURY, IT WAS DISCOVERED THAT SHE HAD SUSTAINED A FRACTURED ANKLE.

## Factual narrative

On June 24, 1993 at 1229 central daylight time, a Boeing 757-222, N579UA, operated by United Airlines, Inc., as flight number 1218, encountered moderate turbulence in the clouds at flight level 290, over Baraboo, Wisconsin, while descending on a vector for an approach runway 14R at Chicago O'Hare International Airport.  The operator reported the seat belt sign was on, the weather radar was on, and the airplane was clear of any green returns on the radar. One flight attendant sustained serious injuries.  There were no injuries to the two cockpit crewmembers, five other flight attendants, or 140 passengers aboard the airplane.  The flight was operating under 14 CFR Part 121, and originated at Vancouver, British Columbia, Canada, at 0920.  The destination was O'Hare Airport.  An IFR flight plan was filed, and instrument meteorological conditions prevailed at the time.

During the turbulence encounter, the flight attendant fell and injured her left ankle.  She was treated for the injury on completion of the flight.  The injury was diagnosed as a fractured ankle.

## Aircraft

- Registration: N579UA (not matched to a registry record)
- Reported make and model: BOEING 757-222
- Category: Airplane
- Serial number: 26697
- Engines: turbo fan
- Damage: No damage
- Flight: Part 121
- Registered owner: United Airlines
- Airworthiness certificate: Standard, Transport
- Departed: YVR, VANCOUVER
- Destination: ORD, CHICAGO, IL
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left

## Weather

- Conditions: Instrument (IMC), Day
- Wind: 160° at 16 knots
- Visibility: 8 statute miles
- Lowest ceiling: 8,500 ft overcast
- Temperature: 84 °F, dew point 72 °F
- Altimeter: 29.00 inHg
- Observed at: MSN, 30 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19930624036859A](https://openairdocs.org/incident/19930624036859A), Jun 24, 1993: Boeing 757222, Baraboo, WI. Descending through FL290 short encounter moderate turbulence. Flight attendant fell and broke her ankle.

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.