Here at Disaster Breakdown we’ve looked at
a lot of different plane accidents. Now just because most of our videos involve planes
doesn’t necessarily mean that things have go wrong in the air. Planes have been known to
crash whilst on the ground. Today we’re going to be looking at one such incident. The case of Dan
Air Flight 0034 that occurred on July 31st, 1979. It’s a tale about negligence,
botched maintenance and oil.
In 1965, reserves of Natural Gas were
discovered off the Coast of East England. For a long time it was long suspected
that the North Sea between Scandinavia and the British Isles held large amounts of
natural resources. Five years later in 1970, British Petroleum discovered large reserves of
oil out here and the North Sea was never the same again. In the following years oil companies from
around the world descended upon these waters.
Oil rigs went up, drilling commended, oil and gas
were extracted and transported back to one of a number of countries which benefitted from access
to the North Sea. The two big, involved countries of which being Norway and the United Kingdom.
Such infrastructure to do this meant transporting many people to and from the oil platforms and
refineries. The easiest way to do that is by air. One of the main gateways to the North Sea
was for the longest time, Sumburgh airport. Located at the southern tip of the Shetland
Archipelago, North East of Mainland Scotland.
The proximity to the oil fields made this the
ideal transport hub for oil workers. The way it would work was workers arrived in on a larger
often chartered plane from Scotland, usually Aberdeen. From there, workers would transfer
to their final destination in the oil industry. Whether that be by Helicopter, sea or land.
The discovery of oil in this region saw passenger numbers explode at Sumburgh’s small
airport. In fact according to statistics, the late 1970s was the peak in terms of passenger
traffic in the airport’s history. Sumburgh was actually one of the busiest airports
in the entire country at this time.
A number of different oil corporations contracted
with British Air Carriers to perform these flights to and from Sumburgh over the years. So there
needed to be a plane that could operate at this small airport. The United Kingdom itself did
happen to have one such plane that could fulfil this role. In 1977, the British Airline Dan
Air sourced a total of 7 British Built Hawker Siddeley HS748 turboprop planes from Argentina.
Energy giant Shell had plenty of operations in the North Sea and so contracted with Dan Air to
charter their HS748s to and from Sumburgh. Amongst these planes was the aircraft registered
as G-BEKF. This was the ill-fated plane.
That kind of gives a background regarding the
accident plane but for this video, we actually need to look at and familiarize ourselves with
Sumburgh Airport itself before we get into the specifics of the disaster. As already mentioned,
Sumburgh airport can be found at the southern tip of Shetland. The airport takes up a large portion
of the land here with the runways spanning in multiple directions. East to West and North to
South. Additionally, there is a third runway used by Helicopters. It is the East/West runway,
runway 09/27 that we are interested in today. If you look at satellite imagery of this airport,
you’ll see that this runway has water on either end. In fact the whole airport itself is almost
surrounded by water given where its located.
This runway today at least measures at 1500
meters in length. The runway was extended a number of years ago but at the time in 1979, it
was only around 1000 meters in length. One of the more interesting things about this airport though
is that the main road route to actually access the Terminal located here, means passengers now
have to cross this runway to reach the airport, so Sumburgh is a rare case of an airport
that actually has a level crossing… I’m not kidding. Point is, this is the primary
runway used at Sumburgh. It takes advantage of regional prevailing winds, there are no
terrain obstacles and also this runway features instrument approach equipment.
A shorter runway obviously means that the aircraft themselves are rather limited in size.
The airport is primarily served by small regional prop airliners. So Sumburgh is an airport that
the Hawker Siddeley 748 fits into rather well. In fact, for many more years after this accident,
the plane was still a common site there. But of course, we are interest in the case of Dan Air
Flight 0034 which brings us to July 31st, 1979.
On the day of the accident, Kilo Foxtrot,
the accident aircraft was scheduled to perform two flights between Aberdeen and
Sumburgh that day, one leg outbound in the morning which was performed without issue
and a return flight in the afternoon.
When the plane arrived in Sumburgh that
morning it spent seven hours on the ground, sitting there idle. Before the pilots left
the plane in the morning, they ran through a procedure to properly park the aircraft as
it would sit in its cold and dark state for hours. This meant applying the aircraft’s
gust locks. And this gets us moving in the right direction in understanding this accident,
the Gust locks. So, what are the Gust locks?
Gust locks are really only found on smaller
planes, and similar to your car steering lock, it locks the flight controls of the plane.
Smaller planes are obviously lighter and so are more vulnerable to damage cause by the
wind. Gust Locks prevent the ailerons, elevators and rudder from flapping about on windy days.
On the HS748 the gust lock controls are located on the console between the pilots, next to
the throttle controls. The gust locks on this plane are purely mechanical, no electrics
involved. To keep it simple, there are three flight control locks on the plane, the lever
in the cockpit actuates all of them. Full down enables all locks whilst fully up disengages
them. There are detents along the channel which the lever sits in that catches the locks.
The lever itself is not just moved forward or backward by the pilots but they must also
lift the lever in order for the mechanism to work. Then push the lever to where it needs to be
followed by a downward press. This sort of caused a bit of wear on the internals of the system.
Now when the manufacturer first developed the plane, beneath this metal housing of the console
they placed what they called a “gate plate”. It was made of a synthetic material that contained
a cut out of these mechanical detents. This was the part that was known for wearing out. So,
Hawker Siddeley notified air carriers that this should be replaced with a steel gate plate.
This notification went out whilst the accident plane was with its previous operators in
Argentina. When investigators later looked through the wreckage of the accident plane, they
discovered this part of the gust Lock system was installed rather poorly. It didn’t really fit.
This was only by a matter of millimetres mind you, but it created an environment where there was
insufficient “interference” as the accident report puts it, between the gate plate and the gate stop.
The Gust lock lever and thus the flight control locking system could be put into a false range
and partly reengage or not fully disconnect.
This damage was deemed not to be a result of
impact damage in the accident but instead the result of botched maintenance. Not only were
non-standard repairs carrier out on the gust lock system on the plane but further checks
on the aircraft in both Argentina and in the United Kingdom failed to pick up on this
issue. So, the aircraft continued to operate with a faulty mechanical gust lock system. It
never caused an issue, until July 31st, 1979.
Once finishing the necessary checklist,
the inbound pilots left the plane, and a new crew was to take the plane
back to Aberdeen later that day.
The pilots themselves, the information we
have is a bit hit and miss. We only the know the name of the captain. 37-year-old Captain
Chris Watson had the majority of his flying experience logged in the HS748. That is 4
and a half thousand out of a total 6 and a half thousand flight hours. He was deemed to be a
very competent pilot through training and exams.
His co-pilot was in contrast very new to the
aircraft. It appears the name of this individual has not been released. But what we do know about
the co-pilot is that they were a 51-year-old man and had logged four and half thousand flight
hours by the time of the accident. Just 57 of those were in this plane. Due to low flight hours
in the aircraft, Dan Air company policy forbid him from handling the flight controls until
he reached 100 hours in the aircraft. Captain Watson was to be in control for this flight.
The two men turned up for work that afternoon. Running through the checklists the pilots
powered the plane back up, the gust locks would seemingly be disabled as normal. The
passengers and flight attendant boarding the aircraft ahead of the departure. 47 passengers
and crew boarded the aircraft. All 44 of the passengers were oil workers, all of them men.
Another unrelated problem with the aircraft meant that the sole flight attendant needed to conduct
the safety demonstration using a megaphone.
The time was 3:48 in the afternoon, flying
as flight 0034, the pilots requested their clearances. After receiving start up clearances,
the pilots began their taxi out to runway 09. To get there from the apron, the pilots
were told to hold position at this point, just short of entering the airport’s other runway.
The plane would hold position here for a total of six minutes due to conflicting traffic.
Perhaps one of the more frustrating aspects of this incident, is that the accident plane did
not have a cockpit voice recorder installed. If you cast you mind back to when we discussed the
accident of British European Airways Flight 548, we mentioned how the investigation recommended
that commercial aircraft in Britain be fitted with a cockpit voice recorder as standard, as
that was case where the investigation really would have benefitted from the presence of one.
The new requirement for a voice recorder only applied to aircraft exceeding a certain size
threshold. The HS748 was a plane below that, and airlines weren’t required to
fit one on smaller planes like this. So, the thing is we don’t know exactly how things
transpired in the cockpit of the Dan Air flight.
It is likely though that during that
6-minute period when the plane was holding, the pilots would have performed
the pre-take-off checklists. Before take-off pilots should check the range of
movement of the flight controls. If you have ever watched a plane while at your local airport you
can clearly see when a pilot does this. They’ll move the ailerons, elevator and most obvious to
an observer, move the rudder. It’s a basic and obvious check a pilot would do, no-one wants
to go flying with inhibited flight controls.
It's believed that the pilots did this check
whilst the plane was holding, but here is where the failure occurred. The pilots did the
flight control check as normal, but the poorly maintained gust lock system failed or slipped
once the check for the elevators was complete. The pilot had pressed the gust lock lever
back down in a false range. The movement of the flight control mechanism when the pilots
were checking the flight controls slipped the locking system into a half-engaged state so that
the elevators were now restricted as if that Lock was fully on. There was no indication to the
pilots that this had occurred, and the pilots failed to pick up on the lever being selected
in an intermediate state. The elevators were now locked, and the pilots had no idea.
Because they did the flight control check and deemed the elevators to be working as
normal, the pilots were none the wiser to the failure that just occurred under their
noses. So, at 3:57, when clearance was given for flight 0034 to taxi into position onto
runway 09, the pilots continued as expected.
There was still some time before take-off,
the pilots needed to backtrack the plane into position. At no point during this
time would they discover the failure.
3:59, Dan Air Flight 0034 was positioned on
Runway 09. Take-off Clearance was received, and the pilots powered up the engines.
Now because the runway was very short, the pilots held the brakes down whilst the
engines powered up. Once the engines were producing the desired thrust the pilots released
the brakes and the plane began to accelerate.
As normal the plane passed the
V1 speed (in this case 92 knots), usually the point pilots are committed to
take-off. At around 100 knots the pilots were expected to pull the plane into the air. Now
at take-off speed, Captain Watson would have expected that he could freely pull the control
wheel back to pitch the nose up into the air.
With his hands on the control wheel, try to
imagine how he must have felt in that moment when he tried to pull the plane up only to find
that the control wheel was locked. The faulty, reenabled gust lock, locked the movement
of the elevators he would have found that he had no movement on the pitch. It was stuck.
For a period of five seconds after the aircraft passed take-off speed, eyewitnesses reported
no take-off, the nose didn’t lift. The plane continued to accelerate. At a speed of 113 knots
the pilots did what seemed like the only option, try and slow the plane down. At this point
the plane had exhausted most of the runway.
The engine power was shut, the pilots hammered the
brakes and began to veer the aircraft to the left, skid marks were left on the runway. Needless
to say, they did not have enough room to stop. The aircraft went off the runway and crashed
through a 40-centimetre-high perimeter step. The landing gear collapsed. The aircraft then skidded
across the perimeter airport road. In the final seconds before the crash, the plane dived over the
inclined sea defence wall of the airport. The left wing made contact and was ripped off. The aircraft
plunged into the sea in a nose down left bank.
The plane came to a rest around 50 meters out
into the water. The plane did not sink at first. Within two minutes of the accident taking place,
emergency services and first responders arrived on the scene and survivors were being pulled from the
aircraft, and the sea. The plane however quickly began taking on water and the nose of the plane
began to sink. The water itself was shallow only around 10 meters in depth, so only the front
end of the fuselage was submerged in water, the tail section was left visible.
This is perhaps the most tragic aspect of this disaster. No one died from the initial crash.
Of the 47 people on board the plane, 29 passengers and the one flight attendant survived. They were
either rescued by those in sea vessels or they swam to safety. In total 30 people were left
uninjured in the crash. The 17 other occupants including the two pilots weren’t as fortunate.
They sadly perished; they weren’t able to make it out of the plane in time. All of those
who died in this accident, died by drowning.
The sole flight attendant on the plane, her
name was Elizabeth Cowe, she was recognized for her efforts in aiding the evacuation of most
of the surviving passengers. In recognition of her bravery, she was awarded an MBE.
In the aftermath of the accident, the investigation recommended that more planes
be fitted with a cockpit voice recorder. Further recommendations were made to re-design
the gust lock system to give clearer indication to pilots of its status. The airport itself was also
looked at. The British Government was to work with the coastguard on rescue procedures at airports
like Sumburgh where the runway ends in water.
Sumburgh continued to be an oil transport hub
for many more years afterward. Dan Air flight 0034 wasn’t even the last time an accident
occurred involving an oil flight at Sumburgh. In 1986 a helicopter crashed shortly before
arriving at Sumburgh. 45 people lost their lives when mechanical failure brought the helicopter
down. For more information consider watching our video on the Sumburgh Helicopter Disaster.
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