Date:	Wednesday 2 May 1984
Time:	12:40 LT
Type:	Boeing Vertol 234LR
Owner/operator:	British Airways Helicopters
Registration:	G-BISO
MSN:	MJ002
Fatalities:	Fatalities: 0 / Occupants: 47
Other fatalities:	0
Aircraft damage:	Substantial
Location:	North Sea, 8 miles WNW of Cormorant Alpha Platform -   United Kingdom
Phase:	En route
Nature:	Offshore
Departure airport:	Magnus oil field/Polycastle rig, North Sea
Destination airport:	Aberdeen Airport (ABZ/EGPD)
Investigating agency:	AIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Ditched 2/5/1984 in the East Shetland Basin of the North Sea, 8 miles WNW of Cormorant Alpha Platform. Lack of flotation bag integrity led the helicopter to capsize and submerge after 85 minutes. All 47 persons on board (44 passengers and 3 crew) escaped through the starboard rear hatchway, and were rescued by rescue boats and helicopters

The aircraft was not damaged by the emergency landing but sustained some damage during recovery and severe damage from the effects of saltwater immersion.

The accident was caused by two separate flying control system malfunctions that produced intermittent loss of collective control. Although the registration G-BISO was cancelled by the CAA as aircraft "destroyed" on 20/11/1984, the airframe was rebuilt as N235CH for Columbia Helicopters International. (First registered as such 23/11/1985)

1. AAIB: https://www.gov.uk/aaib-reports/5-1987-boeing-vertol-bv-234-lr-g-biso-2-may-1984
2. CAA: https://cwsprduksumbraco.blob.core.windows.net/g-info/HistoricalLedger/G-BISO.pdf
3. https://en.wikipedia.org/wiki/British_Airways_Helicopters#Accidents_and_incidents
4. https://www.key.aero/forum/historic-aviation/87795-spectacular-mystery-accident-nobody-hurt-who-s-got-the-details [photos]
5. https://www.helis.com/database/cn/1419/
6. https://en.wikipedia.org/wiki/Cormorant_oilfield
7. https://www.thenorthernecho.co.uk/news/1095132.100-killed-oil-rig-copter-accidents-since-1969/
8. https://www.helis.com/database/gps/cormorant_a_platform_uk

I'm a bit puzzled by your statistics, in view of the disastrous G-BWFC accident at Sumburgh, in addition to G-BISO which I think you are probably referring to. With regard to the former, this may interest. Brilliantly written, if grim reading: https://t.co/Rkr98ZtFqt

— DaddyPeb (@StrutThePeb) December 21, 2020

Date/time	Contributor	Updates
02-Jan-2010 08:34	TB	Added
03-Jan-2010 02:51	TB	Updated [Damage, ]
05-Apr-2010 05:38	TB	Updated [Aircraft type, Narrative, ]
19-Nov-2012 16:18	Dr. John Smith	Updated [Destination airport, Source, Embed code, Narrative, ]
23-Dec-2012 09:17	TB	Updated [Source, Narrative, ]
03-Nov-2015 22:44	Dr.John Smith	Updated [Time, Cn, Operator, Location, Source, Embed code, Narrative, ]
03-Nov-2015 22:46	Dr.John Smith	Updated [Departure airport, ]
03-Nov-2015 22:49	Dr.John Smith	Updated [Narrative, ]
03-Nov-2015 22:53	Dr.John Smith	Updated [Embed code, ]
21-Jan-2016 20:46	Aerossurance	Updated [Time, Aircraft type, Location, Source, ]
24-Sep-2016 14:45	Aerossurance	Updated [Narrative, ]
01-Mar-2017 16:08	TB	Updated [Time, Location, Source, ]
17-Aug-2022 21:59	Dr. John Smith	Updated [Location, Departure airport, Destination airport, Source, Embed code, Category, ]