SHERIFFDOM OF NORTH STRATHCLYDE
FATAL ACCIDENTS AND SUDDEN DEATHS INQUIRY
(SCOTLAND) ACT 1976
FATAL ACCIDENT INQUIRY CHINOOK MkII ZD576
DETERMINATION AND NOTE BY SHERIFF SIR STEPHEN
|II||THE LEGAL FRAMEWORK
|III||THE EVIDENCE GENERALLY
|IV||THE BACKGROUND TO THE ACCIDENT
|V||THE FINAL FLIGHT OF ZD576
|VI||THE AAIB INVESTIGATION/RACAL REPORT
|VII||THE CAUSE OF THE ACCIDENT
|IX||COCKPIT VOICE RECORDER AND ACCIDENT DATA RECORDER
PAISLEY, 21 MARCH 1996
[Sidenotes omitted editorially]
The Sheriff, having resumed consideration of the evidence
and submissions thereon, determines as follows:
1. Chinook MkII helicopter ZD576 was delivered to RAF
Aldergrove on 31 May 1994. It had recently been the subject of
a mid-life update by its manufacturers, Boeing Helicopters.
2. The operation of ZD576 was subject to the terms of
the CA Release issued by the Controller Aircraft who is responsible
to the Secretary of State for Defence. The CA Release, which may
be amended from time to time, certifies the airworthiness of the
type of aircraft to which it relates within the particular limitations
set forth therein. At the material time ZD576 was subject to limitations
in respect of weight and icing clearance.
3. On 2 June 1994 in the late afternoon ZD576 was tasked
to carry a group of 26 passengers from RAF Aldergrove to Fort
George near Inverness. In the event only 25 passengers went on
4. The crew of ZD576 for the flight to Fort George were
Flt Lt Tapper (captain), Flt Lt Cook (co-pilot) and MALM Forbes
and Sgt Hardie (crewmen).
5. Before departure of the flight the crew obtained from
the Met Office at Belfast International Airport up-to-date terminal
area forecasts and actual observations which covered their planned
route to Fort George. The forecast for the Machrihanish area was
that visibility in general would be 7,000 metres in haze with
the scattered cloud base at 1,200 feet and the broken cloud base
at 3,000 feet and that temporarily between 1400 and 2100GMT the
visibility would be 4,000 metres with the broken cloud base at
500 feet. In addition there was a 30 per cent probability that
between these times the visibility would be reduced to 500 metres
in fog with the broken cloud base at 100 feet. The actual observations
taken at Machrihanish at 1416GMT indicated that the visibility
was 4,800 metres in haze with the scattered cloud base at 200
feet and the broken cloud base at 800 feet.
6. The journey to Fort George was planned by the crew
to be flown under Visual Flight Rules (VFR) at low level on the
way out and at medium level on the return to RAF Aldergrove.
7. Before departure the crew left with an operations
clerk at RAF Aldergrove copies of three sections of a 1:500000
scale map on which had been recorded details of the planned route
to Fort George including tracks, distances, estimated times and
safety altitudes for each leg of the sortie.
8. The planned route was to fly from RAF Aldergrove to
the lighthouse at the Mull of Kintyre, thence to Corran near Fort
William and thence up the Great Glen to Inverness and Fort George.
On the first leg to the lighthouse the track was shown as 027ºM,
the distance 42 nautical miles (nm), the time 21 minutes and the
safety altitude 2,800 feet.
9. During pre-flight procedures, the crew entered five
waypoints into the aircraft's RNS252 SuperTANS computer. Waypoint
A was entered as N55º 18.50 W005º 48.00 which was a
point approximately 280 metres south east of the Mull of Kintyre
lighthouse. Waypoint B was entered as a point near Corran.
10. In due course the 25 passengers boarded the aircraft
and at 1642GMT (1742BST) a member of the crew reported to Aerodrome
Control at Belfast International Airport that the aircraft was
lifting and departing.
11. At 1643GMT a member of the crew reported to Approach
Control at the airport that the aircraft was outbound on a course
of 027ºM at low level. At 1646:14.06 a further report was
received from the aircraft to the effect that it was at the airport
zone boundary (approximately 9nm from the airport) flying VFR.
These reports were all routine and unexceptional.
12. During the flight Flt Lt Tapper occupied the left
hand seat in the cockpit of the aircraft and acted as non-handling
pilot while Flt Lt Cook occupied the right hand seat and acted
as handling pilot. MALM Forbes acted as No 2 crewman at the front
of the cabin while Sgt Hardie acted as No 1 crewman at the rear.
13. At about 1750BST the aircraft was observed flying
at low level over Carnlough on the Antrim coast and out over the
North Channel in the direction of the Mull of Kintyre.
14. At 1655:14GMT a member of the crew called the Scottish
Air Traffic Control Centre (Military) at Prestwick in the following
terms: "Scottish Military, good afternoon, this is F4J40"
(which was the aircraft's callsign). This was not an emergency
call. For reasons which are not known the call was not answered.
Nor was it repeated. No further radio communications were heard
from the aircraft.
15. At the time or shortly after this call was made the
aircraft was observed flying below the cloud base at a height
between 200 and 400 feet and at a point about 2nm south west of
the Mull of Kintyre lighthouse. It was in straight and level flight
and heading in the direction of the land mass of the Mull at a
16. At this time cloud and hill fog extended over the
land mass from approximately the base of the lighthouse building
(at 250 feet above sea level) to at least the summit of Beinn
na Lice (1404 feet) which is situated a little under 1nm east
of the lighthouse.
17. When the aircraft was about 0.81nm from the position
entered into the SuperTANS for the lighthouse (waypoint A) on
a bearing of 018ºT a member of the crew manually changed
the waypoint displayed on the SuperTANS (which was in Tactical
Steering mode) so as to give steering, distance and time to go
information to Corran (waypoint B).
18. This change of waypoint was made when the aircraft
was approximately 400 to 500 feet above sea level.
19. After the change of waypoint the aircraft flew towards
the land mass of the Mull on an ascending track of 022ºT
(which was approximately two degrees to the right of the track
which the crew had planned to follow from RAF Aldergrove to the
lighthouse and nine degrees to the right of the planned track
from the lighthouse to Corran).
20. A few seconds after the change of waypoint (and about
15 to 18 seconds prior to impact with the land mass of the Mull)
the aircraft was at a height of 468 plus or minus 50 feet above
21. At some stage the aircraft entered Instrument Meteorological
Conditions (IMC). This required the aircraft to transfer to flight
under Instrument Flight Rules (IFR), and in particular to climb
at least as high as the calculated safety altitude for that leg
of the route, namely 2,800 feet.
22. At a point in time some 2.9 seconds before the initial
impact, the aircraft was climbing at a rate of approximately 1,000
feet per minute and at an airspeed of approximately 150 knots.
To this speed there fell to be added a tailwind component of approximately
24 knots which resulted in a groundspeed of approximately 174
23. At that point in time large aft and left cyclic and
collective control inputs were made in the aircraft which resulted
in a final cyclic flare before the aircraft struck the ground.
During this final flare the aircraft travelled approximately 812
feet over the ground, increased its rate of climb to approximately
4,670 feet per minute and climbed approximately 128 feet. In addition
the flight path angle increased to 20º above the horizontal
and the nose of the aircraft was pitched up to about 31º
above the horizontal.
24. The distance between the point where the change of
waypoint was made and the initial impact point was about 0.95nm.
25. The aircraft initially struck a rocky outcrop on
the side of Beinn na Lice at a point 810 feet above mean sea level
and approximately 0.28nm east of the Mull of Kintyre lighthouse.
26. At the time of the initial impact the aircraft was
travelling at a groundspeed of approximately 150 knots on a track
of approximately 012ºT. It was banked some 5 to 10º
to the left with a yaw angle of less than 10º.
27. Upon initial impact much of the fuselage undersurface
of the aircraft and rear end was torn off and the right and lower
area of the cockpit damaged.
28. The aircraft then travelled almost 200 metres airborne
while sustaining fuselage strikes from rotor blades and executing
extreme violent manoeuvres. It impacted the ground inverted and
broke into two major pieces which tumbled a short distance, shedding
the aft pylon and both engines. Fuel tanks on both sides were
ruptured at initial impact and extensive ground fire initiated,
severely damaging much of the remains.
29. The time of the initial impact was approximately
1759:30BST on 2 June 1994. All the occupants of the aircraft were
rendered unconscious at once and died more or less instantaneously.
30. The names of those who died, and the cause of death
in each case, were as follows:
|Richard Allen||Chest and head injuries due to aircraft accident.
|Christopher John Biles||Multiple injuries due to aircraft accident.
|Dennis Stanley Bunting||Severe chest injuries due to aircraft accident.
|Desmond Patrick Conroy||Multiple injuries due to aircraft accident.
|Richard David Cook||Multiple injuries due to aircraft accident.
|Martin George Dalton||Severe head and chest injuries due to aircraft accident.
|Philip George Davidson||Multiple injuries due to aircraft accident.
|Stephen Davidson||Multiple injuries due to aircraft accident.
|John Robert Deverell||Multiple injuries.
|Christopher John Dockerty||Multiple injuries due to aircraft accident.
|John Charles Brian Fitzsimons||Massive chest injuries due to aircraft accident.
|Graham William Forbes||Severe head and chest injuries due to aircraft accident.
|Robert Patrick Foster||Severe head and chest injuries due to aircraft accident.
|Richard Lawrence Gregory-Smith||Multiple injuries due to aircraft accident.
|William Rutherford Gwilliam||Massive chest injuries due to aircraft accident.
|Kevin Andrew Hardie||Multiple injuries due to aircraft accident.
|John Stuart Haynes||Multiple injuries due to aircraft accident.
|Anthony Robert Hornby||Severe head and chest injuries due to aircraft accident.
|Anne Catherine MacDonald or James||Severe chest and abdominal injuries due to aircraft accident.
|Kevin Michael Magee||Multiple injuries due to aircraft accident.
|Michael Bruce Maltby||Severe chest injuries due to aircraft accident.
|Maurice McLaughlin Neilly||Multiple injuries due to aircraft accident.
|John Turbitt Phoenix||Multiple injuries due to aircraft accident.
|Roy Pugh||Multiple injuries due to aircraft accident.
|Stephen Lewis Rickard||Multiple injuries due to aircraft accident.
|Gary Paul Sparks||Severe chest and abdominal injuries due to aircraft accident.
|Jonathan Paul Tapper||Massive head injury due to aircraft accident.
|John Tobias||Severe chest and pelvic injuries due to aircraft accident.
|George Victor Alexander Williams||Multiple injuries due to aircraft accident.
31. The wreckage of the aircraft was subsequently examined
in very considerable detail by Mr Cable, a Senior Inspector of
Air Accidents (Engineering) with the Air Accidents Investigation
Branch (AAIB) of the UK Department of Transport, assisted by various
colleagues and other personnel from Boeing Helicopters, a number
of component manufacturers and the RAF.
32. Fire damage to the wreckage of the aircraft was consistent
with the effects of the accident. No evidence of explosive effects
or pre-impact fire were found.
33. The completeness of the aircraft at impact could
not be positively verified but no evidence was found to suggest
pre-impact separation of any part.
34. The groundspeed and drift indicator of the aircraft
was probably registering 147 knots groundspeed at, or very shortly
after, the initial impact.
35. Engine condition and the available evidence of instrument
indications and control settings in the aircraft suggested normal
operation of both engines at the time of the accident.
36. Fire damage prevented assessment of the functionality
of No.1 DECU and had destroyed its memories of the operating program
and exceedance and fault history.
37. The No.2 DECU remained partially functionable, with
deficiencies that were consistent with the effects of impact damage.
38. The No.2 DECU memories showed that the operating program
and constants had not altered since delivery, that no abnormal
exceedances or faults had been detected over its life and that
no faults had been detected on the last flight.
39. HMA internal settings confirmed correct operation
for most HMA elements and indicated power levels that possibly
reflected aircraft manoeuvre effects.
40. Thorough assessment of most flight control hydraulic
system components of the aircraft was possible and revealed no
signs of pre-impact failure or malfunction. Available cockpit
indications indicated that both systems were providing normal
pressure at impact.
41. Available evidence indicated normal AFCS operation.
42. Available evidence precluded major pre-impact loss
of electrical supplies but indicated that all electrical systems
had probably de-energised almost immediately on initial impact.
43. No signs of pre-impact malfunction of the transmission
or rotor systems were found.
44. Almost all parts of the flight control mechanical
systems of the aircraft were identified, with no evidence of pre-impact
failure or malfunction, although the possibility of control system
jam could not be positively dismissed.
45. Most attachment inserts on both flight control system
pallets had detached, including the collective balance spring
bracket that had previously detached from the aircraft's thrust/yaw
pallet, with little evidence available to eliminate the possibility
of pre-impact detachment.
46. The method of attaching components to the pallets
appeared less positive and less verifiable than would normally
be expected for a flight control system application.
47. The aircraft's radar altimeter receiver was excessively
sensitive, probably a pre-existing condition that was mainly the
result of incorrect adjustment. The fault had the potential for
causing erroneous height indication but a previous flight test
result indicated that this was unlikely, provided the antenna
environment for the aircraft was similar to that for the test.
48. The radar altimeter receiver's excessive sensitivity
would have increased the maximum indicated height error build-up
in circumstances where the terrain closure rate exceeded the system's
49. A detailed investigation of possibly relevant technical
aspects of the accidents was made. The pre-impact serviceability
of the aircraft could not be positively verified but no evidence
was found of malfunction that could have contributed to the accident,
with the possible exception of the radar altimeter system fault.
50. The aircraft was not fitted with either a cockpit
voice recorder or an accident data recorder. Had these been fitted
it is likely that they would have led to the recovery of important
evidence relevant to the circumstances of the deaths and, more
particularly, the cause of the accident.