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Accident description
Last updated: 21 June 2018
Status:Final
Date:Sunday 16 August 2015
Time:14:55
Type:Silhouette image of generic AT43 model; specific model in this crash may look slightly different
ATR 42-300
Operator:Trigana Air Service
Registration: PK-YRN
C/n / msn: 102
First flight: 1988-05-28 (27 years 3 months)
Total airframe hrs:50133
Cycles:55663
Engines: 2 Pratt & Whitney Canada PW120
Crew:Fatalities: 5 / Occupants: 5
Passengers:Fatalities: 49 / Occupants: 49
Total:Fatalities: 54 / Occupants: 54
Aircraft damage: Destroyed
Aircraft fate: Written off (damaged beyond repair)
Location:16,7 km (10.4 mls) NW of Oksibil Airport (OKL) (   Indonesia)
Crash site elevation: 2530 m (8301 feet) amsl
Phase: En route (ENR)
Nature:Domestic Scheduled Passenger
Departure airport:Jayapura-Sentani Airport (DJJ/WAJJ), Indonesia
Destination airport:Oksibil Airport (OKL/WAJO), Indonesia
Flightnumber:IL257
Narrative:
Trigana Air Service flight 257, an ATR 42-300, was destroyed when it impacted a mountainside near Oksibil Airport in Papua, Indonesia. All 49 passengers and five crew members sustained fatal injuries.
The ATR-42 departed Jayapura at 14:22 LT (05:22 UTC) and was expected to arrive at Oksibil at 15:04 LT (06:04 UTC).
At 14:55 the pilot made first contact with Oksibil Aerodrome Flight Information Services (AFIS), reporting cruising at 11500 feet over position Ambisibil. The AFIS controller acknowledged the message and instructed the pilot to report when overhead the airport. The pilot reported that they intended to fly a direct left base leg for runway 11. The Oksibil AFIS officer then told the pilot to continue approach and to call when position on final for runway 11.
There was no further contact with the flight.
The aircraft wreckage was found the next day on a ridge of Tanggo Mountain at approximately 8,300 feet AMSL, about 17 km from the airport.

The investigators concluded that the flight crew deviated from the standard approach procedure over mountainous terrain. There was no EGPWS warning nor any other EGPWS callout during the descent. The Oksibil Airport was not provided with the high-resolution terrain data in the database version installed on the accident aircraft's EGPWS.
Additionaly, some pilots within the air operator had experiences that the EGPWS warning became active in a condition that according to the pilots, the warning is not appropriate. These experiences led to the pilot behaviour of pulling the EGPWS circuit breaker to eliminate nuisance of EGPWS warning that considered unnecessary.
The investigators could not determine the actual EGPWS CB position during the accident flight.

Probable Cause:

Contributing Factors:
1. The deviation from the visual approach guidance in visual flight rules without considering the weather and terrain condition, with no or limited visual reference to the terrain resulted in the aircraft flew to terrain.
2. The absence of EGPWS warning to alert the crew of the immediate hazardous situation led to the crew did not aware of the situation.

Accident investigation:
cover
Investigating agency: NTSC Indonesia
Status: Investigation completed
Duration: 2 years and 5 months
Accident number: KNKT.15.08.17.04
Download report: Final report

Classification:
Controlled Flight Into Terrain (CFIT) - Mountain

Sources:
» BASARNAS


Follow-up / safety actions

NTSC issued 3 Safety Recommendations

Show all AD's and Safety Recommendations

Photos

photo of ATR 42-300 PK-YRN
photo of ATR 42-300 PK-YRN
photo of ATR 42-300 PK-YRN
final flight path
photo of ATR 42-300 PK-YRN
Trigana's circling approach procedure for runway 11
photo of ATR 42-300 PK-YRN
Terrain profile and expected EGPWS response
photo of ATR 42-300 PK-YRN
predicted aircraft flight track after passing point MELAM
photo of ATR 42-300 PK-YRN
photo of ATR 42-300 PK-YRN
Add your photo of this accident or aircraft
 

Aircraft history
date registration operator remarks
28 May 1988 F-WWEZ ATR first flight
22 August 1988 F-GFTO ATR new registration
29 September 1988 N421TE Resort Air bought
1 October 1989 N421TE Trans States Airlines transferred
13 December 1990 N421TE Trans States Airlines Incident: Blew 2 tyres after swerving on landing Madison, WI. Cause: Steering differential valve defective.
16 Jun 1997 N421TE Trans States Airlines Incident: Evacuated following left engine fire warning during taxi At St. Louis, MO. Warning was false. Cause: Bleedair duct leak.
8 August 1999 N421TE Trans States Airlines Incident: Diverted to Springfield, IL after left engine was shut down due to "low oil pressure" warning.
23 July 2000 N421TE Trans States Airlines Incident: Emergency landing due to flight control difficulty while in cruise flight. Cause: Failure of aileron trim switch due to foreign material contamination.
5 February 2003 N421TE Trans States Airlines Incident: Emergency diversion to Bloomington, IL after crew saw and smelled smoke.
23 February 2003 N421TE Trans States Airlines Incident: Nose gear axle broke; right wheel separated during taxi at St. Louis, MO.
21 January 2005 PK-YRN Trigana Air Service bought

Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Jayapura-Sentani Airport to Oksibil Airport as the crow flies is 258 km (161 miles).
Accident location: Exact; as reported in the official accident report.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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ATR-42

  • 457+ built
  • 31st loss
  • 9th fatal accident
  • The worst accident
» safety profile

 Indonesia
  • 14th worst accident
» safety profile