Controlled
Flight Into Terrain (CFIT) – Introduction
Human
error is the major cause of UK general aviation accidents. Controlled Flight
Into Terrain (CFIT) is a major cause of UK general aviation fatal accidents.
CFIT accidents are a classic example of human error by the pilot concerned.
In this issue we examine two CFIT accidents in an attempt to find some
common factors and to alert both fixed-wing and rotary-wing pilots to the
hazards that lead to these avoidable fatalities.
Controlled Flight Into Terrain accidents may
appear to be the most avoidable of all fatal accidents. Yet they continue to
happen, causing untold loss to the families of those who die and a feeling
approaching helplessness among those who try to prevent aircraft accidents.
In a future
issue of Gremline we will look at an accident that came about through flying
up a valley below an overcast sky. The valley narrowed and the valley floor
climbed towards the cloudbase that was below the tops of the surrounding
mountains. Why would two qualified pilots, both with current instrument
flying qualifications, continue on a track that took them directly into the
vertical face of a cloud-covered mountain? Loss of situational awareness?
Navigation error? Lack of appropriate and positive action in deteriorating
weather? “It’ll get better in a few more minutes”?
“We can climb out/turn around if it doesn’t get better
soon.”? Perhaps some or all of these factors apply, but CFIT accidents
do not only result from descending through cloud, or holes in the cloud, into
the ground. A common factor in CFIT accidents to GA aircraft is the human
attribute described as ‘press-onitis.’ A pilot becomes determined
to press-on towards his destination despite deteriorating weather, probably
in the hope that either the weather will improve or else he can scrape home
below the cloudbase in marginal visibility.
These accidents often occur at weekends when the
pilot is faced with some inconvenience if he returns to his point of
departure or accepts the need for a diversion en route to his destination.
Remember the old joke about “Cheer up! Things could be worse.”
“So I did, and they were.” In this context we will look at an
accident where the pilot and his wife paid with their lives for pressing-on
towards their destination in deteriorating weather after a weekend flight.
A light helicopter with a pilot not equipped
for instrument flying seems to me to offer the option of a precautionary
landing almost anywhere, assuming the pilot has chosen a sensible route away
from heavily built-up areas.
In this issue we
examine the probable causal links between spatial disorientation and one, and
possibly two, CFIT accidents. Spatial Disorientation was discussed in broad
terms in the
May 2008 issue of Gremline but is
a wide subject that merits study by all pilots. Spatial disorientation
contributes to more aircraft accidents than any other physiological problem.
Knowledge of the triggers for spatial disorientation and methods to overcome
its onset can greatly increase the safety of all flight operations.
Some accidents are forgivable in that a
pilot, through no fault of his own, is faced with a sudden and unforeseen
situation that is simply beyond his skill to handle. Most accidents are the
result of a chain of circumstances that combine in a cumulative manner to
overwhelm the skill and experience levels of a pilot who probably flies fewer
hours per year than are required to keep him fully current in the many skills
involved in flying any type of aircraft.
In my opinion, the vast majority of CFIT
accidents are totally unforgivable in that the pilot knowingly pushed his
luck and flew his aircraft beyond the boundaries of his own skill and
experience. As mentioned above, CFIT accidents are often the result of
‘pressing on’ into deteriorating weather instead of recognising
the need for a diversion, a precautionary landing or a simple 180 degree turn
back to the departure point to wait for another day.
In the past some UK
GA pilots may have hesitated to make a timely diversion to a nearby airfield
when the weather began to close in because they feared a huge bill for
landing fees when they arrived at their diversion. Thanks to the efforts of
Charles Strasser of AOPA this is no longer a consideration in Britain as the
vast majority of UK civil, and ALL military, airfields have agreed not to
charge GA pilots for a genuine diversionary landing. (Our tables of
UK Emergency Diversion
Airfields
were last updated in October 2008). Pilots in the southern
parts of England can never be very far away from a suitable and free
diversionary airfield. Those in remoter parts of the UK are more likely to be
a considerable distance from any airfield, so their flight requires even more
careful planning when thinking of available ‘bolt holes.’
Standards of weather forecasting have made huge advances in the last 20 years
or so and accurate weather information is readily available from many
sources. There is no excuse for getting into the air without having an accurate
and up-to-date weather picture in your mind, with a copy in your hand.
The commonest scenario leading to a CFIT
fatality is where the pilot blunders into deteriorating weather and continues
to try to reach his destination until he either loses control in cloud or
smashes into the ground in bad visibility.
A
Weekend Trip to Disaster — Jodel DR1050
A Jodel DR1050 owned by a
syndicate of which the pilot was a member was operated from Inverness
Airport. He held a PPL without any instrument qualification or training. His
total experience amounted to 216 hours with 126 hours on type accumulated
over a period of seven years, an average of 18 hours per year. He had flown 4
hours in the last 90 days and 1 hour in the last 28 days.
He and his wife flew from Inverness to Dornoch on
a Sunday in May to take some friends on local sight-seeing flights. The
flight from Inverness to the unlicensed grass airfield at Dornoch took twenty
minutes at 2000 feet, with the pilot having to find a break in the cloud
before landing at Dornoch. The first sight-seeing flight was flown below
cloud at about 400 feet agl. The passenger on the second similar flight
recalled that the aircraft stall warning light had illuminated during a turn
but the pilot appeared unconcerned. Syndicate members were aware that the
stall warning tended to operate well above stalling speed.
The pilot completed pre-flight external
checks before he and his wife entered the aircraft for the return flight to
Inverness. They were seen to fasten their lap and diagonal seat belts before
departing at 15.12 hrs.
The actual weather at Inverness Airport
timed at 14.50 hrs gave a surface wind of 040/07 kt varying between 010 and
080 degrees, visibility of 8,000 metres in light rain showers with few clouds
at 400 feet, scattered at 2,500 feet and broken at 4,500 feet. The visibility
had dropped to 5,000 metres with scattered cloud at 400 feet by 15.20 hrs. A
special observation at 15.28 hrs recorded few clouds forming at 100 feet
above the surface.
The pilot contacted Inverness Tower at 15.20
hrs to report passing Tain (an inactive Danger Area), VFR inbound for
Inverness. He was instructed to continue VFR to report field in sight and was
passed the weather and airfield details. At 15.25 hrs the Inverness
controller advised the Jodel pilot of a very low cloudbase at Fort George and
the Beauly Firth, to the west of Inverness. The pilot replied that he was at
the Nigg oil rig fabrication yard 1nm north of Cromarty and still VFR with a
cloudbase of 400 feet. A direct track from there to Inverness Airport would
involve crossing the Cromarty Firth, overflying Cromarty town and then
crossing ground rising to 512 ft amsl and passing close to the Rosemackie
transmitter mast standing 1,074 ft amsl before crossing the Moray
Firth.
At 15.30 hrs the commander of a BAe 146
inbound to Inverness from the west reported for the benefit of the Jodel
pilot that there was a break in the low cloud so that the threshold of Runway
06 was visible from Inverness town. There was no response to this or further
transmissions.
A witness in his house in Cromarty town
heard the loud sound of an aircraft overflying the town. He went to his
garden and saw the Jodel banked steeply to the left circling into the mist.
He saw the aircraft circle twice and heard it circle a further three times
before it moved away towards the rising ground to the south-west. A second
witness heard the aircraft approach his house that stood 1km south-west of
the town on higher ground. He saw the aircraft “very very low
travelling towards Inverness. It followed the contours of the rising ground
dipping its wings to the left before disappearing over the crest of the hill
in a wings level attitude at a height half that of the nearby trees.”
Some moments the aircraft struck the ground and both occupants suffered fatal
injuries.
The aircraft came to rest inverted on the
top of a 340 ft amsl hill. Ground marks indicated that the Jodel had crashed
on a heading of 280° M and then rotated through 270° before coming to rest 6
feet further on. The aircraft had been pitched to at least 30° beyond the
vertical, turning to the left at a speed of about 60 kt on impact. The engine
was at low power. The airbrakes were unlocked and drooped about one inch from
the closed position but their position before the crash could not be
determined. There was no evidence of any pre-impact failure.
The AAIB came to the conclusion that the
pilot, untrained for instrument flying and attempting to remain VMC, appeared
to have become disorientated and crashed into rising ground, perhaps having
stalled while attempting to climb through the low cloud.
Summary
The
probability is that the Jodel was actually out of control on impact so
perhaps it would be more accurate to classify this accident as being caused
by Spatial Disorientation. BUT the pilot knowingly flew his aircraft into
deteriorating weather until the situation got to the point where he could no
longer control his aircraft. Perhaps he could have diverted to a nearby
airfield with better weather. Perhaps he could have checked the weather at
Inverness before leaving Dornoch. Perhaps he should have delayed the flight
from Inverness to Dornoch for another day; but he had the pressure of having
arranged to take his friends at Dornoch for their sight seeing flights.
94 Seconds to Impact — Robinson R44
A Robinson R44, with a crew of two
and one passenger, crashed into cloud-covered groundnear Chroley, Lancashire,
at 16.45 hours UTC in early February, killing the three people on board. This
review of the accident is closely based on AAIB Field Investigation Ref:
EW/C2000/02/01 which source is gratefully acknowledged.
A Bell 206 helicopter flew two pilots from
Coventry to Blackpool to collect the Robinson R44 and return to Coventry
where the Robinson R44 was to be used for pilot training. The Bell 206
carried two passengers, one of whom decided to return to Coventry in the
Robinson R44 instead of travelling back in the Bell 206. The crew of the R44
consisted of the commander who held a PPL(H) with an Instructor Rating
and another pilot who held a PPL(H) and was converting to the Robinson
helicopter. The commander was qualified to instruct on both the R22 and R44
and to fly at night. He had a total of 737 hours with 11 hours on the R44.
The other pilot was qualified as pilot-in-command of the Bell 206 and the
Robinson R22. He had a total of 88 hours on helicopters with 2 hours on the
R44. Neither pilot was trained or qualified to fly by sole reference to
flight instruments.
The commander of the Bell 206, with one
passenger, agreed to follow the Robinson R44 in loose formation back to
Coventry. The R44 had a more capable navigation system and a more experienced
commander. The weather on departure from Blackpool was good with no
significant cloud and good visibility. A cold front was moving south through
the area with extensive low cloud and reduced visibility in rain to the south
of the front, between Blackpool and Coventry. The two helicopters departed
Blackpool at 16.33 hrs and contacted Warton Radar two minutes later. They
climbed from 700 feet amsl to 1,000 feet amsl once they were south of Warton.
The R44 commander confirmed with Warton that he intended to transit the
Manchester Low Level Route and then onwards to Coventry. At 16.42 hrs the R44
informed Warton Radar that he was descending to 600 feet to remain clear of
cloud. He also said that he intended to follow the M6 motorway to the Low
Level Route. At 16.44 hrs he reported his position as just south of Leyland
and intended to turn through 180 degrees to remain clear of cloud. The Bell
206 pilot, following the R44 at about 60 yards, saw the R44 turn left and
enter cloud. The Bell 206 also turned left but remained clear of cloud and
settled on a westerly heading.
Warton Radar asked the R44 commander if he
was happy with his position as he was three miles north west of Winter Hill
radio mast that rises to 2452 feet above mean sea level. The R44 commander
replied, “We’re actually in the cloud now can you give us some
vectors?” The time was 1644:10 hrs. The following transmissions were
recorded:
1644:16 Warton to R44: “Head west
now make the heading 270. I’ll take you back towards the M6 and you can
pick up the M6.”
1644:24 R44 to Warton: “Affirm we
are turning right east … was that east to follow the M6?”
1644:30 Warton to R44: “No go west
onto heading 270 … can you fly the heading?”
1644:33 R44 to Warton: “Affirm
…west turning left onto west 270.”
1645:00 Warton to R44: “Squawk for
me 3641.”
1645:04 R44 to Warton: “3641 ..
we’re actually in a bit of trouble now .. if you can give us a bit of
assistance … we’re climbing to 1500 feet to get out of the
cloud.”
1645:27 Warton to R44: “Just
confirming I do have you identified you’re 12 miles south east of
Warton make the heading 270 to take you back towards the M6.”
1645:42 R44 to Warton: “Helicopter
Golf Mike Echo we’re in trouble.”
1645:44 No response to transmissions
from Warton Radar.
The pilot
of the Bell 206 requested radar vectors to the last recorded position of the
Robinson R44 but could not reach the position because the high ground was
covered by cloud. He then continued to Coventry. A police helicopter offered
assistance and made several attempts to locate the crash site until it was
forced by fuel shortage to return to base.
Recorded
radar data showed the R44 crossed the M6 at Leyland before following the M61
until abeam Chorley where it began a left turn towards high ground, when the
pilot reported entering cloud. The speed had been steady at 100 kt until then
but increased to 113 kt on entering cloud before reducing to 65 kt over the
next minute. It then recovered briefly to 83 kt before reducing again to 67
kt.
The helicopter hit the ground at a high rate
of descent on a track of 060 degrees magnetic. It was pitched slightly nose
down and moderately banked to the right with some right sideslip. The
groundspeed was of the order of 60 kt. The skids dug into soft ground and the
fuselage and lower cabin disrupted. The cabin floor was dragged under the
fuselage as the aircraft rolled rapidly forward and onto its right side with
the rotor mast and head striking the ground heavily. A 2 metre piece of the
outer main rotor blade was thrown 85 metres from impact. The complete
instrument binnacle lay 45 metres from the impact point.
There was no evidence of any pre-impact
failure. There was no clear indication of any instrument warning caption
light being lit prior to impact, but AAIB considered the evidence to be
inconclusive because of the relatively low impact forces involved. All
circuit breakers were still set except the attitude indicator circuit breaker
which had tripped. It was considered likely that this circuit breaker had
popped because of shorting in the wiring harness during the break-up
sequence. The attitude indicator was examined in detail and found to be
operating correctly without drift in pitch or roll.
Summary
The flight
was uneventful until the two helicopters crossed the M6 motorway near Leyland
and began to follow the M61 motorway southwards. This was not as planned by
the R44 commander and suggests that he may have crossed the M6 without seeing
it in the deteriorating visibility and lowering cloudbase. He became unsure
of his position and recognised the hazard of continuing southwards so
announced his intention of turning through 180 degrees, away from the
worsening weather. Unfortunately, he turned left towards high ground. This
reinforces the supposition that he had become lost, as a right turn would
have taken him away from high ground towards flat country. The R44 then
entered the lowering cloud and the commander, not being trained or qualified
in instrument flying, realised that he was in a dangerous situation. The R44
instrument panel was fitted with an ASI, VSI, altimeter, magnetic compass and
artificial horizon identical to the R22 that was more familiar to the
commander. The R44 was also fitted with a Garmin 150 GPS and a Skyforce
Tracker that could show the aircraft’s position on a map display. The
commander of the R44 was not familiar with the GPS/Tracker equipment and it
was not intuitive in its set-up procedure. This equipment was destroyed on
impact and nothing could be recovered from the memory. It was not possible to
say if the GPS was used during the accident flight. Several 1:250,000
topographical charts covering the intended route were found in the
wreckage.
Radar recorded an erratic flight path during
the last minute and a half, suggesting that the pilot had become
disorientated and lost control of the helicopter. The commander’s
confusion of ‘east’ for ‘west’ may also indicate a
high mental workload while he was trying to resolve the disorientation. The
pilot did not have the ability or training to recover control before the
aircraft struck the cloud-covered high ground.
The
physiological problem of spatial disorientation is one of many subjects dealt
with in “Aviation Medicine” [edited by Ernsting and King and
available from our
Bookshop]. The very real hazards
of spatial disorientation are succinctly summarised as follows: “The
ability to maintain control of an aircraft without adequate visual cues is
quite short, typically about 60 seconds, even when the aircraft is in
straight and level flight at the time vision is lost, and shorter still if
the aircraft is in a turn. In such circumstances, loss of control occurs
because the non-visual receptors give either inadequate or erroneous
information about the position, attitude and motion of the aircraft.”
A common factor in
both these CFIT accidents is that the pilots concerned allowed themselves to
go beyond their own abilities and training and to get their aircraft into a
situation that was unrecoverable. It is vitally important that all pilots, no
matter how experienced, qualified and skilled, should be aware of their own
limitations and the limitations of their aircraft. If you have the slightest
doubt about anything to do with a planned flight then the best thing to do is
to return to your armchair and resolve that doubt before you get into the
aircraft.
A superior pilot is one who uses his judgement to avoid
having to use his superior skill.
Text and Photographs © 2008 Gremline & Hill House
Publications, unless otherwise stated.
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