# NTSB ANC93IA007: Boeing 737-200, N673MA, Anchorage, AK, October 8, 1992

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: October 8, 1992, 09:39 local (17:39 UTC)
- Place: Anchorage, AK
- Coordinates: 69.21936, -146.789642 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=69.2194&lon=-146.7896&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 26 uninjured
- Status: Completed, report October 8, 1993
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- NTSB case key (mKey): 5838
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC93IA007
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/5838/pdf
- Page: https://openairdocs.org/ntsb/ANC93IA007

## Probable cause (aircraft 2)

IMPROPER ATC CLEARANCE INSTRUCTIONS BY THE APPROACH CONTROLLER, RESULTING IN A FAILURE TO INSURE SAFE SEPARATION BETWEEN AN AIRPLANE IN VISUAL CONDITIONS WITH AN AIRPLANE IN INSTRUMENT METEOROLOGICAL CONDITIONS ON CONVERGING COURSES. A FACTOR WHICH CONTRIBUTED WAS INSUFFICIENT INFORMATION PROVIDED TO BOTH PILOTS BY THE CONTROLLER.

## Sequence of events

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

- Near collision between aircraft, approach - iaf to faf/outer marker (ifr)
  - atc clearance - improper, atc personnel(dep/apch) (cause)
  - information insufficient, atc personnel(dep/apch) (contributing factor)
- Near collision between aircraft, approach - vfr pattern - downwind
  - atc clearance - improper, atc personnel(dep/apch) (cause)
  - information insufficient, atc personnel(dep/apch) (contributing factor)

## Analysis (aircraft 2)

THE DHC-8, N680MA, WAS NORTH BOUND IN RADAR CONTROL APRX 8 NM FROM ANC INTL ARPT, AND WAS PROVIDED VISUAL SEPARATION FROM THE B-737, N673MA, NE BOUND ON APCH TO ELMENDORF AFB. THE B-737 WAS IN CLOUDS AT THE TIME OF THE ADVISORY, AND THE DHC-8 MISTOOK ANOTHER B-737 FOR VISUAL SEPARATION. THE TCAS ALERTED THE FIRST B-737 PILOT OF CLOSE PROXIMITY OF TRAFFIC APPROACHING AT AT HIS 2 O'CLOCK POSITION, AND HE INITIATED A CLIMB IN IMC. A RAPID DESCENT WAS INITIATED BY THE DHC-8 PILOT AFTER SEEING THE B-737 EMERGING FROM THE CLOUDS. THESE EVASIVE ACTIONS OCCURRED APPROXIMATELY 20 SECS PRIOR TO THE CROSSING OF THE TRACKS OF THE TWO AIRPLANES. ATC CONTROL OF THE CONFLICTING AIRPLANES WAS BY THE SAME POSITION CONTROLLER ON SEPARATE FREQUENCIES. THE B-737 PILOT WAS NOT ADVISED NOR AWARE OF THE DHC-8 BEING PROVIDING VISUAL SEPARATION FROM HIS AIRPLANE PER FAA ORDER 7110.65G UNTIL THE TCAS PULL-UP AND VISUAL SIGHTING OF THE TRAFFIC PASSING UNDER AND IN FRONT.

## Aircraft 1

- Registration: N673MA (not matched to a registry record)
- Reported make and model: BOEING 737-200
- Category: Airplane
- Engines: P&W JT8D-9A turbo jet
- Damage: No damage
- Flight: Part 121
- Operator: Mark Air, Inc, doing business as Mark Air
- Registered owner: Mark Air, Inc
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, January 2, 1900
- Departed: AKN, KING SALMON, AK
- Destination: EDF, ELMENDORF AFB, AK
- Flight plan: IFR

## Aircraft 2

- Registration: [N680MA](https://openairdocs.org/deregistered/N680MA-1993-04-22), registration cancelled 1993-04-22, S/N 242 (OpenAirDocs)
- Reported make and model: DE HAVILLAND DHC-8
- Registry model: [Boeing Of Canada/Dehav Div DHC-8-311](https://openairdocs.org/model/boeing-of-canada-dehav-div-dhc-8-311) (registry code 1386006) (OpenAirDocs)
- Category: Airplane
- Engines: turbo prop
- Damage: No damage
- Flight: Part 121
- Operator: Mark Air Inc.
- Registered owner: Mark Air Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, January 2, 1900
- Departed: ADQ, KODIAK, AK
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot, aircraft N673MA; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, unknown; seat: left
- Pilot, aircraft N680MA; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: valid medical--no waivers/lim.; seat: left

## Weather

- Conditions: Visual (VMC), Day
- Wind: 170° at 11 knots
- Lowest ceiling: 2,800 ft broken
- Temperature: 39 °F
- Altimeter: 29.00 inHg
- Observed at: ANC, 4 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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