Accident Fokker F-28 Fellowship 1000 LN-SUY,

ASN Wikibase Occurrence # 330296

Date:	Saturday 23 December 1972
Time:	16:34
Type:	Fokker F-28 Fellowship 1000
Owner/operator:	Braathens SAFE
Registration:	LN-SUY
MSN:	11011
Year of manufacture:	1969
Total airframe hrs:	8228 hours
Cycles:	16710 flights
Engine model:	Rolls-Royce Spey 555-15
Fatalities:	Fatalities: 40 / Occupants: 45
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	16 km W of Oslo-Fornebu Airport (FBU) - Norway
Phase:	Approach
Nature:	Passenger - Scheduled
Departure airport:	Ålesund-Vigra Airport (AES/ENAL)
Destination airport:	Oslo-Fornebu Airport (FBU/ENFB)
Investigating agency:	Flyhavarikommisjon
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Braathens flight 239 turned some 10 NM ahead of the ILS-procedure for runway 06 at Oslo-Fornebu Airport while the captain was having private communications regarding Christmas with the ACC-controller. The F-28 also descended below MSA and the crew lowered the gear and flaps as it was established on the ILS. It then flew into the woods more than 4 NM off course in darkness and fog.

Accident cause (translated from Norwegian):

The probable cause of the aircraft LN-SUY that crashed near Asdoltjern in Asker on 23 December 1972 at 1634:55 was incorrect navigation under a truncated instrument approach to runway 06 at Fornebu.
The fact, which could not to specifed more closely, however, must have been committed when the aircraft left 3500 feet but was not fatal for the last 13 seconds when it was flown 1510 feet below the glide path down while aboard it must have been clear that neither was at or within 2 1/2° from the ILS facility centerline.

Contributing factors:
a) The aircraft's ADF no. 2 was probably tuned to 100 kHz erroneously.
b) Fornebu ILS to runway 06 provides useable glideslope signals from Sylling to the accident site.
c) Outer Marker on Steilene can provide convincing signals for passage of an outer Marker Beacon in apparently correct glidepath altitude between Sylling and the accident site in the F-28 aircraft if "merkefyrbryteren" are put in setting HIGH.

Unfortunate circumstances:
a) The commander was not as rested as he could have been according to regulations
b) The commander made radio calls with air traffic controller in the control tower that were not allowed during the initial phase of the approach.
c) Control tower bearing indicator was moved from its fixed position in the control desk, so that the possibility of random directional control was reduced.
d) Training Position for approach control at Oslo ATCC was unmanned.

Accident investigation:


Investigating agency:	Flyhavarikommisjon
Report number:	Final Report
Status:	Investigation completed
Duration:	2 years and 11 months
Download report:	Final report