STSECR
3/f/R046/9/86
HAMPSHIRE POLICE AUTHORITY ITEM 5
23RD SEPTEMBER, 1986
THE CRASH OF OPTICA G-KATY ON 15TH MAY 1985
Report of the Clerk
This report deals with the Report of the Accidents Investigation
Branch (AIB) of the Department of Transport, which was published on
20th August. A further (confidential) report on the Authority's
liability in respect of the death of the late Police Constable
Spencer (the pilot) and the late Detective Constable Wiltshire (the
passenger) will be brought to the Authority in November.
1. The AIB's report (a copy of which is in the Members Room) has
received wide and diverse media coverage. G-KATY was orbiting
the town of Ringwood and during the third (or fourth) orbit was
seen to descend slowly from about 800 feet to between 150 and 100
feet, and then to enter a steep, but apparently controlled, turn
to the right. A few seconds later the bank angle suddenly
increased to about 90~ and the aircraft spiralled steeply into a
wood, destroying the aircraft and killing the crew. 20 to 30
seconds after impact a severe fire broke out. The death of two
experienced serving officers was made more poignant because G
KATY was the first production-model Optica produced by Edgeley
Aircraft Limited and was formally accepted by the Hampshire
Constabulary on the previous day for the purpose of evaluating
the suitability for police purposes (delivery being taken 15 days
earlier for training and conversion purposes). The crew had been
tasked with carrying out a photographic survey of the traffic
congestion in the area of Ringwood during market day on the 15th
May.
2. Despite an exhaustive examination at the crash site and
subsequent examination and trials of aircraft components at
Farnborough, the AIB conclude that it was not possible to
identify the cause of the events which resulted in the crash.
3. The AIB report records the flight of G-KATY from its base at
Lee-on-Solent to Ringwood. The flight profile was normal, the
pilot having received Hurn Air Traffic Control approval to
operate between 500/1000 feet and the aircraft arrived at
Ringwood at 10.32 am. The next and last communication with Hurn
was at 10.37 am when clearance was given for a climb up to
1500 feet for what would have been the routine taking of a final
photograph of the overall scene. There was no mention of any
difficulties, but a few seconds before the accident, at 10.40 am
the aircraft was flying at between 100/150 feet, the descent
taking place from about 800 feet in the course of the last orbits
of the town. The AIB report analyses four possible causes.
4. An intentional descent below normal reconnaissance height does
not accord with the operational task of the flight or the request
to Hurn to increase height. An inadvertent descent over a
minimum of two minutes is discounted as is incapacitation of the
pilot in view of the smooth and apparently controlled manner in
which the aircraft manoeuvred. The possibility of an enforced
descent by the jamming of the flying controls by an object in the
cockpit is also discounted.
5. An enforced descent through engine malfunction and some loss of
power by a transient condition of the engine (possible causes of
which are examined in detail) is considered a possibility. Such
a malfunction could have been the consequence of the selection of
an engine control and the report dwells at length on the fuel
selector switch. The AIB examined selector switches on other
Opticas and found that in certain circumstances a mis-selection
to the OFF position could be made and that there was relative
difficulty in rectifying it.
6. The report mentions two factors which might lend credibility to
the fuel selector hypothesis. The position and design of that
switch (controlling the intake of fuel from the aircraft's two
tanks) is consistent with the evidence of witnesses who saw the
crew "fiddling" with something in the middle of the cockpit where
the engine controls were located. The aircraft had been flying
for just under 30 minutes, which is the time the crew would
consider changing the fuel supply from one tank to another. An
inadvertent mis-handling of the fuel selector switch, leading to
a loss of power, would exactly match the course of events, likely
reasons for the continuation of the orbit and the AIB's findings
about difficulties in the correct handling of the switch in other
Opticas. The report says that the evidence of the initial
descent tends to support the hypothesis of inadvertent
mishandling of the fuel selector switch.
7. The report says that the circumstances of the final steep turn to
the right, at the end of the right hand turning final orbit
(seconds before the crash) depends on what is believed to be the
reason for the initial descent. One possibility was that the
passenger, who was sitting on the right side of the aircraft, may
have felt insecure through a combination of the perspex "bubble"
cockpit and the inertia reel upper torso restraint. On one
similar previous occasion, a passenger had grabbed the central
control column causing a sudden increase of bank angle (here from
a 45~ bank turn to one of 90~) which would cause the nose of the
aircraft to enter a spiral.
8. If there had been an engine malfunction the pilot would have been
looking for a forced landing site. The fields west of the town
appear initially to be suitable, but a closer inspection reveals
that they are obstructed by power lines and narrow ditches, as
again, on close inspection is the field just west of the crash
site. The one remaining hospitable field is a few metres
north-east of the copse into which the aircraft crashed and
rigorous application of controls would be required to achieve the
necessary landing position. This is consistent with what the
aircraft appeared to do, but because of the concentration
required to locate a landing area, or perhaps the inability to
apply power, the aircraft may have been flying below the critical
speed for that manoeuvre. The flying characteristics of the
Optica make the unexpected control input by the passenger the
more likely of the two possibilities. Regardless of the final
steep turn the aircraft then had insufficient height for the
pilot to recover form either event before impact with the ground.
9. The AIB's analysis is that detailed examination of the aircraft
and its systems failed to identify any defect relevant to the
accident, and that prior to impact the aircraft was serviceable,
but that a transient power loss could not be dismissed. The
evidence of 300+ witnesses provided no direct evidence of the
reasons for the initial descent or the final spiral. The most
likely reason for the initial descent was a transient engine
malfunction, however caused, and that the final spiral was either
the result of interference with the controls or a stall (too low
a speed) in the final turn.
10. In respect of pilot training and experience the AIB say there is
no doubt that the training of the Constabulary's Air Support
pilots was conceived and carried out in a most professional
manner; the ASU had an accident-free record. Nevertheless the
use of private pilots to perform aerial work of such demanding
and precise nature did leave itself open to question - not
because they are less safe than professional pilots, but because
of continuity of training and greater degree of competence gained
in the acquisition of a professional licence. On the other hand
a professional licence would not necessarily best qualify pilots
for this type of operation. A specialist licence for tasks
pertintent to the requirements of this kind of flying is
recommended, to the Civil Aviation Authority as are changes in a
Home Office memorandum on the use of radios above 500 ft and the
Air Navigation Order, to permit police aircraft to operate at low
level. A copy of the AIB's Conclusions, and Safety
Recommendations is attached.
RECOMMENDATION
That this report be noted and that a report on the
Authority's liability arising out of the crash be brought to the
next meeting.
3/f/R046/9/86
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