# NTSB CHI91IA175: Douglas DC-9-32, N933ML, Kansas City, MO, May 29, 1991

- Type: NTSB incident investigation
- Classification: Incident · Minor injuries · Incident investigation · Final report
- Date: May 29, 1991, 13:00 local (18:00 UTC)
- Place: Kansas City, MO
- Location: 39.0997° N, 94.5786° W: Placed by OpenAirDocs: center of Kansas City, MO, within about 10 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=39.0997&lon=-94.5786&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 6 minor, 40 uninjured
- Status: Completed, report May 5, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 14930
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI91IA175
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14930/pdf
- Page: https://openairdocs.org/ntsb/CHI91IA175

## Probable cause

INADEQUATE DESIGN BY THE MANUFACTURERS.   FACTORS ASSOCIATED WITH THE INCIDENT ARE INADEQUATE CERTIFICATION/APPROVAL BY THE FEDERAL AVIATION ADMINISTRATION AND CLEAR AIR TURBULENCE.

## Sequence of events

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

- In flight encounter with weather, cruise - normal
  - weather condition - turbulence,clear air (contributing factor)
- Airframe/component/system failure/malfunction, cruise - normal
  - misc eqpt/furnishings,seat belt - disengaged
  - acft/equip,inadequate design, manufacturer (cause)
  - inadequate certification/approval, faa(organization) (contributing factor)

## Analysis

THE INCIDENT AIRPLANE ENCOUNTERED CLEAR AIR TURBULENCE WHILE FLYING IN VISUAL METEOROLOGICAL CONDITIONS AT 10,000' MSL.  THE AIRPLANE WAS NOT DAMAGED DURING THE ENCOUNTER AND THE SEAT BELT SIGN WAS ON.  SHORTLY AFTER THE ENCOUNTER THE CAPTAIN WAS ADVISED BY THE CABIN CREW THAT THERE HAD BEEN INJURIES IN THE CABIN DURING THE TURBULENCE.  THE FLIGHT CONTINUED TO ITS DESTINATION WHERE IT WAS MET BY PARAMEDICS.  SIX PERSONS, THREE FLIGHT ATTENDANTS AND THREE PASSENGERS, WERE TRANSPORTED TO A LOCAL HOSPITAL, TREATED FOR MINOR INJURIES AND RELEASED.  ONE PASSENGER SEAT BELT SEPARATED FROM ITS ATTACHMENT POINT ON THE SEAT FRAME.  EXAMINATION OF THE SEAT BELT SHOWED A DISTORTED KEEPER CLIP ON THE HOOK ASSEMBLY.

## Aircraft

- Registration: [N933ML](https://openairdocs.org/deregistered/N933ML-1993-06-08), registration cancelled 1993-06-08, S/N 47548 (OpenAirDocs)
- Reported make and model: DOUGLAS DC-9-32 (DC9-32)
- Registry model: [Douglas DC-9-31](https://openairdocs.org/model/douglas-dc-9-31) (registry code 3022065) (OpenAirDocs)
- Category: Airplane
- Serial number: 47548
- Engines: P&W JT8D turbo fan
- Damage: No damage
- Flight: Part 121
- Operator: Midway Airlines
- Airworthiness certificate: Standard, Transport
- Departed: MDW, CHICAGO, IL
- Destination: MCI, KANSAS CITY, MO
- 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, unknown

## Weather

- Conditions: Day
- Wind: 200° at 11 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 88 °F, dew point 73 °F
- Altimeter: 29.00 inHg
- Observed at: MCI, 27 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).

- [Incident 19910529022919I](https://openairdocs.org/incident/19910529022919I), May 29, 1991: Doug DC931, Kansas City, MO. Encountered clear air turbulence on descent. Three passengers and two flight attendants injured. A seat belt broke.

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.

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