# NTSB CHI90IA166: Mcdonnell Douglas DC-9-32, N948ML, Chicago, IL, June 29, 1990

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: June 29, 1990, 09:10 local (14:10 UTC)
- Place: Chicago, IL
- Coordinates: 41.779251, -87.770851 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.7793&lon=-87.7709&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 65 uninjured
- Status: Completed, report May 10, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 14568
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI90IA166
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14568/pdf
- Page: https://openairdocs.org/ntsb/CHI90IA166

## Probable cause

THE PILOT-IN-COMMAND'S INADEQUATE WEATHER EVALUATION. FACTORS IN THE INCIDENT WERE THE WEATHER AND ARTCC'S FAILURE TO ISSUE A WEATHER ADVISORY.

## Sequence of events

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

- In flight encounter with weather, descent - normal
  - weather condition - thunderstorm,outflow (contributing factor)
  - weather evaluation - inadequate, pilot in command (cause)
  - weather condition - turbulence,clear air (contributing factor)
  - interpretation of instructions - not issued, nws personnel (contributing factor)
  - autopilot/flight director - engaged
  - airspeed - improper, pilot in command
  - flight control,speed brake - open
- Loss of control - in flight, descent - uncontrolled
  - remedial action - performed, pilot in command

## Analysis

A PASSENGER TRANSPORT EXPERIENCED SEVERE TURBULENCE DURING AN EN ROUTE DESCENT TO DESTINATION. THE FLIGHT'S FORECAST INDICATED THUNDERSTORM DEVELOPMENT IN THE DESTINATION VICINITY. THE CREW HEARD DESTINATION ATIS ANNOUNCE SEVERE TURBULENCE ON APPROACH BUT RECALLED NO ATC ADVISORY STATING TURBULENCE WAS SEVERE. THE PILOT COMPLIED WITH ATC'S REQUEST TO SLOW FOR TRAFFIC SEPARATION, PLACING THE SPEED BELOW THAT RECOMMENDED FOR TURBULENCE PENETRATION. THE AIRPLANE WAS TURNING TO AVOID CLOUDS AND VIRGA, WITH SPEEDBRAKES EXTENDED AND AUTOPILOT ENGAGED WHEN IT ENTERED INCREASING TURBULENCE. THE AIRPLANE PITCHED UP 20 DEGREES AND ROLLED TO 45 DEGREES. THE PILOT RIGHTED THE AIRPLANE AND STOPPED THE DESCENT 500 FEET BELOW ASSIGNED ALTITUDE. SPEED BRAKE EXTENSION INCREASES ROLL RATE. AUTOPILOT USE IN SEVERE TURBULENCE IS RECOMMENDED ONLY IN THE PITCH-HOLD MODE.

## Aircraft

- Registration: [N948ML](https://openairdocs.org/deregistered/N948ML-2014-11-19), registration cancelled 2014-11-19, S/N 47169, built 1968 (OpenAirDocs)
- Reported make and model: MCDONNELL DOUGLAS DC-9-32
- Registry model: [Douglas DC-9-32](https://openairdocs.org/model/douglas-dc-9-32) (registry code 3022066) (OpenAirDocs)
- Registry engine: [Pratt & Whitney JT8D-9 series](https://openairdocs.org/engine/pratt-whitney-jt8d-9-series) (registry code 52048, turbo-jet) (OpenAirDocs)
- Category: Airplane
- Serial number: 47169
- Engines: P&W JT8D-9B 14500 lbs thrust turbo jet
- Damage: No damage
- Flight: Part 121
- Registered owner: Midway Airlines, Inc.
- Airworthiness certificate: Standard, Transport
- Departed: DCA, WASHINGTON, DC
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 40; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 15,580 total, 8,000 in this make and model, 8,170 as pilot in command, 220 in the last 90 days, 73 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 280° at 14 knots
- Visibility: 15 statute miles
- Lowest ceiling: 9,000 ft overcast
- Temperature: 70 °F, dew point 66 °F
- Altimeter: 29.00 inHg
- Observed at: MDW, 33 nm away

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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