# NTSB ATL90GA023: Sikorsky SK-70, N23576, Marathon, FL, November 3, 1989

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Final report
- Date: November 2, 1989, 21:30 local (Nov 3, 1989, 02:30 UTC)
- Place: Marathon, FL
- Coordinates: 24.710319, -81.080078 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=24.7103&lon=-81.0801&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal, 2 minor, 3 uninjured
- Status: Completed, report September 5, 1991
- Report: Approved by Office Director
- NTSB case key (mKey): 8152
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL90GA023
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8152/pdf
- Page: https://openairdocs.org/ntsb/ATL90GA023

## Probable cause

FAILURE OF THE PILOT TO MAINTAIN THE PROPER ALTITUDE OVER THE OCEAN WATER.  FACTORS RELATED TO THE ACCIDENT WERE:  CONTINUED OPERATION OF THE HELICOPTER WITH A KNOWN PARTIAL DEFICIENCY OF THE RADIO ALTIMETER/WARNING SYSTEM, DARKNESS, THE PILOT'S LACK OF VISUAL PERCEPTION, FAILURE OF THE COPILOT TO ADEQUATELY MONITOR THE HELICOPTER'S ALTITUDE ABOVE THE WATER, AND INSUFFICIENT MANAGEMENT STANDARDS TO IDENTIFY INORDINATE FLIGHT RISKS.

## Sequence of events

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

- In flight collision with terrain/water, maneuvering
  - light condition - dark night (contributing factor)
  - flight/nav instruments,altimeter,radio - failure,partial (contributing factor)
  - operation with known deficiencies in equipment - continued (contributing factor)
  - insuff standards/requirements,operation/operator, other govt organization (contributing factor)
  - terrain condition - water
  - proper altitude - not maintained, pilot in command (cause)
  - visual/aural perception, pilot in command (contributing factor)
  - monitoring - inadequate, copilot/second pilot (contributing factor)

## Analysis

THE HELICOPTER WAS ON A NIGHT LAW ENFORCEMENT MISSION OVR THE OCEAN NR MARATHON, FL. AFTER TKOF, THE PIC NOTED THE RADARALTIMETER NEEDLE, WHICH ACTIVATED THE LOW ALT WARNING, WAS NOT FUNCTIONAL, THOUGH THE DIGITAL DISPLAY & COPLT'S RADAR ALTIMETER WERE OPERATING NORMALLY. AFTER ENTERING THE MISSION AREA, THE PIC BGN RANDOM MNVRS WITH THE ALT VARYING BTN 200 & 300 FT ABV THE WATER. THERE WAS AN ESTD 1000 FT OVC SKY COND WITH NO VISIBLE HRZN. BOTH PLTS WERE WEARING NIGHT VISION GOGGLES. THE COPLT OPERATED THE SEARCH LIGHT & WAS TO MONITOR THE INSTS. WHILE MNVRG TO KEEP A BOAT IN VIEW, THE HELICOPTER BGN DSCNDG & CONTACTED THE WATER. IMMEDIATELY, THE CABIN FILLED WITH WATER. ALL OF THE OCCUPANTS EGRESSED SUCCESSFULLY FM THE HELICOPTER, EXCEPT THE COPLT, WHO PRESUMABLY DROWNED. THE PIC & 2 OF THE OTR CREWMEMBERS WERE NOT INJURED; THE REMAINING 2 RCVD MINOR INJURIES. AN AGENCY OPNS HANDBOOK DISCUSSED HAZARDS/INCIDENTS, BUT NO MISSION RISK ASSESSMENT PROGRAM WAS IN PLACE FOR MANAGEMENT TO ADEQUATELY IDENTIFY THE LEVEL OF RISK ASSOCIATED WITH THE OPN.

## Aircraft

- Registration: N23576 (not matched to a registry record)
- Reported make and model: SIKORSKY SK-70
- Category: Helicopter
- Serial number: 81-23576
- Airframe hours: 2016
- Engines: GE T700-GE-700 1560 horsepower turbo shaft
- Damage: Destroyed
- Flight: Public aircraft, Part 91
- Registered owner: U.S. States Customs Service
- Last inspection: Continuous airworthiness, September 24, 1989, 2 hours before
- Departed: HST, HOMESTEAD AFB, FL
- Destination: HST
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane, helicopter; medical: class 2, valid medical--no waivers/lim.; seat: right; toxicology performed; flight hours: 4,758 total, 490 in this make and model, 4,503 as pilot in command, 73 in the last 90 days, 31 in the last 30 days

## Weather

- Conditions: Visual (VMC), Night/dark
- Wind: variable at 9 knots
- Visibility: 10 statute miles
- Lowest ceiling: 1,000 ft broken
- Temperature: 75 °F, dew point -0 °F
- Altimeter: 29.00 inHg

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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