# NTSB DEN90IA012: Mcdonnell Douglas DC-9, N922RW, Monte Vista, CO, October 18, 1989

- Type: NTSB incident investigation
- Classification: Incident · Minor injuries · Incident investigation · Final report
- Date: October 18, 1989, 00:15 local (06:15 UTC)
- Place: Monte Vista, CO
- Coordinates: 37.569057, -106.139228 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=37.5691&lon=-106.1392&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor, 102 uninjured
- Status: Completed, report January 8, 1991
- Report: Approved by Office Director
- Safety recommendations: Yes
- NTSB case key (mKey): 17849
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN90IA012
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17849/pdf
- Page: https://openairdocs.org/ntsb/DEN90IA012

## Probable cause

THE POOR INFLIGHT PLANNING AND DECISIONS MADE BY THE FLIGHT CREW FOLLOWING THE FAILURE OF THE NUMBER TWO GENERATOR CONSTANT SPEED DRIVE UNIT. CONTRIBUTING FACTORS TO THE ACCIDENT WERE THE FAILURE OF THE NO. 2 GENERATOR CONSTANT SPEED DRIVE UNIT AND THE CREW'S INADVERTENT SHUT DOWN OF THE WRONG GENERATOR WHICH RESULTED IN A COMPLETE LOSS OF ELECTRICAL POWER.

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise - normal
  - electrical system,constant speed drive unit - leak (contributing factor)
  - electrical system,constant speed drive unit - failure,total (contributing factor)
  - generator - inadvertent deactivation, pilot in command (contributing factor)
  - apu - not attained, pilot in command
  - aircraft manuals,system information - inadequate
  - inadeq substantiation process,inadeq documentation, company/operator mgmt
  - electrical system - failure,total (contributing factor)
- Overrun, landing - roll
  - in-flight planning/decision - improper, pilot in command (cause)
  - unsuitable terrain or takeoff/landing/taxi area - selected, pilot in command (cause)
  - lowering of flaps - not performed, pilot in command
  - landing gear,gear indicating system - inoperative
  - insufficient standards/requirements,aircraft, manufacturer

## Analysis

WHILE IN CRUISE AT FL350 THE NO. 2 GENERATOR CONSTANT SPEED DRIVE (CSD) FAILED AND THE CREW INADVERTENTLY DISCONNECTED THE NO. 1 GENERATOR CSD. ATTEMPTS TO START THE APU ABOVE THE START ENVELOPE WERE MADE BUT ABORTED DUE TO A HOT START. A DESCENT WAS MADE ON EMERG ELECTRICAL POWER AND A LANDING WAS MADE AT AN ARPT WHICH WAS INADEQUATE FOR THE ACFT. THE CREW CHOSE TO MAKE A NO FLAP APCH AND TO LOWER LANDING GEAR BY EMERG METHOD WHEN BOTH SYSTEMS WERE OPERABLE BY NORMAL MEANS. THIS DECISION WAS INFLUENCED BY THE LACK OF LANDING GEAR AND FLAP POSITION INDICATORS WHEN THE ACFT IS OPERATED ON BATTERY POWER. THE LANDING SPEED WAS FAST AND THE ACFT DEPARTED THE END OF THE RWY DAMAGING THE LANDING GEAR AND THE NO. 1 ENGINE. THE CREW FAILED TO MANUALLY DEPRESSURIZE THE ACFT AND THE EVACUATION WAS DELAYED UNTIL A KNOWLEDGEABLE PASSENGER WENT TO THE COCKPIT AND DEPRESSURIZED THE ACFT. THE OPERATORS ACFT OPERATING MANUAL DID CONTAIN APU STARTING PROCEDURES BUT NOT AN APU START ENVELOPE CHART.

## Aircraft

- Registration: [N922RW](https://openairdocs.org/deregistered/N922RW-2007-12-01), registration cancelled 2007-12-01, S/N 47182, built 1968 (OpenAirDocs)
- Reported make and model: MCDONNELL DOUGLAS DC-9
- Registry model: [Douglas DC-9-31](https://openairdocs.org/model/douglas-dc-9-31) (registry code 3022065) (OpenAirDocs)
- Registry engine: [Pratt & Whitney JT8D-1](https://openairdocs.org/engine/pratt-whitney-jt8d-1) (registry code 52044, turbo-jet) (OpenAirDocs)
- Category: Airplane
- Serial number: 47182
- Airframe hours: 61931
- Engines: P&W JT8D 17000 lbs thrust turbo fan
- Damage: Minor damage
- Flight: Part 121
- Registered owner: Northwest Airlines
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, October 13, 1989, 68 hours before
- Departed: MSP, MINNEAPOLIS, MN
- Destination: PHX, PHOENIX, AZ
- Flight plan: IFR
- Airport: 08V, Monte Vista, runway 2, 6,000 × 60 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 15,730 total, 12,335 in this make and model, 6,500 as pilot in command, 176 in the last 90 days, 70 in the last 30 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Night/dark
- Wind: 150° at 8 knots
- Visibility: 15 statute miles
- Lowest ceiling: 3,500 ft overcast
- Temperature: 37 °F
- Altimeter: 30.00 inHg
- Observed at: PUB, 100 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.

---
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.