It was November of 1970 and the United
States Military Airlift Command had chartered a Capitol Airways
DC-8, N4909C, to transport 219 service personnel from Tacoma,
Washington to Vietnam. The flight plan called for two fuel stops,
the first in Anchorage, Alaska. Under the command of captain William
Reid, first officer James Downs, flight engineer Edward Fink, and
flight navigator Robert Leonard, the aircraft touched down in
Anchorage just after 3:30pm on the 27th.
Nightfall comes early in that part of the world
during the winter and it was already dark with light sleet falling
as 09C began servicing on the ramp. The aircraft was sprayed down
with heated ethylene glycol to remove ice that had accumulated as it
sat in the freezing precipitation. With the passengers loaded and
the 10 crew members in place, 09C taxied away from the terminal to
runway 06R shortly before 5pm. The wind was light and visibility was
just under 5 miles with and overcast layer at 1600ft. Downs would be
handling the controls for the takeoff, but Reid taxied the aircraft
into position on the icy runway and informed the crew that he would
handle the brakes throughout the takeoff. Even though the aircraft
was near maximum gross weight, with some 10,000ft of available
runway, they were well within limits of making their Vr speed of
When cleared for takeoff, Reid held the brakes
while advancing the power to 80%. He then released the brakes and
Downs maintained directional control as Reid brought the engines up
to full takeoff power. The aircraft appeared to accelerate normally,
but V1 came a few moments late. Acceleration the became increasingly
sluggish, but the aircraft achieved Vr with over 1,500ft of runway
remaining. Downs brought the nose of the aircraft up into the
takeoff attitude, but for some reason, the aircraft failed to climb
away from the runway. Six seconds later, still in the nose-up
attitude, the aircraft ran out of runway. Reid closed the throttles
and attempted to stop the aircraft, but it ploughed through
navigation structures and hit a drainage ditch which caused the
aircraft to break up. Fuel from both wings ignited and the aircraft
slid to a stop 3,000ft from the end of the runway.
Reid, uninjured, exited through his cockpit
window and immediately began evacuating passengers. Finding the
flight deck door blocked, he went back outside and entered Downs'
window and assisted Downs, Fink, and Leonard out to safety. Despite
the flight crew's efforts and the quick response of fire crews, 46
people died in the post-crash fire.
......Several of the survivors reported that about halfway through
the takeoff roll, there were several loud explosions which they
believed to be the main tires blowing out. These sounds were not
audible from the flightdeck and there was no accompanying vibration.
Examination of the runway area revealed evidence to support the
passengers claims however. The tire tracks appeared normal from the
taxiway to the runway holding point. There was a clear "footprint"
where the warm tires had melted through the ice while the aircraft
waited in position for takeoff on the runway. From this point on,
however, skid marks were found along the entire length of the runway
and evidence of tire deterioration increased along the takeoff path.
The first piece of tire rubber was found only
about 500ft down the runway. By about 4,000ft, all of the port tires
had blown out and all the starboard tires by 8,000ft. Examination of
the wheels still intact after impact showed that they had all been
ground down on only one side indicating that they were not rotating
during the takeoff roll. The brakes all appeared to be in normal
working order and the parking brake was found in the "off" position.
No evidence of any malfunction of the system was found.
......The NTSB requested that NASA (National Aeronautics and Space
Administration) conduct tests on the rolling and sliding friction
caused by aircraft tyres. The concern was that the tire could
produce a sliding coefficient of friction so low on ice that they
would fail to spin up after brake release. NASA concluded in all
cases that the tires would release and spin up normally. However,
further testing revealed an interesting discovery. The initial tests
were conducted on frosted and glazed ice which resulted in friction
coefficients which were still considerably higher than the normal
wheels-rolling friction coefficient. 09C, however, had been sitting
in position which allowed the ice directly in contact with the tires
This liquid water on top of the ice reduced the
friction coefficient to such a degree that it was almost identical
to the normal wheels-rolling friction coefficient. Under these
circumstances, the aircraft could initially accelerate without the
wheels rolling with little hesitation. Analysis of the FDR showed
that the aircraft accelerated almost normally up to about 100kts.
After this, the deterioration of the tire surface began to increase
the friction coefficient and progressively decrease performance.
The aircraft only reached a maximum speed of 1
knot below Vr. Investigators believed, however, that the wheels
should have begun to spin normally unless brake pressure was held
prior to the takeoff role and not released. No evidence was ever
found to support this and both crew members were sure that the
brakes had been released prior to the aircraft's takeoff role.
Although the FDR showed evidence of decreased performance after
passing through 100kts, the progressive nature of the problem
hindered the crew's ability to make a prompt and correct analysis
and correction of the difficulties. The crew's actions were not
cited as contributing to the accident, but the NTSB suggested that
FAA should revise takeoff procedures to allow crews to evaluate
takeoff performance at all points in the takeoff roll.
...... As I stated above, investigators believed that brake pressure
had to be applied AND HELD prior to the takeoff roll in order for
the tires to have slid throughout the takeoff roll. It was clear
that Reid had applied the toe brakes prior to bringing up power, but
he then released them. Downs supported this by saying that he felt
no pressure on the pedals as he controlled the aircraft on takeoff.
Barring a failure of the hydraulic system, which was damaged by
fire, there was no evidence in the mechanical brake system to
indicate that they were applied. This was a highly experienced crew,
each with nearly 14,000 hours, all having over 2,000 hours on the
DC-8 itself. They showed good cockpit organization and adherence to
checklists and procedures.
I believe that further study of the frictional
data may indicate what actually happened. Breakaway friction
coefficient is determined by thrust to weight ratios. With the
aircraft at its takeoff weight, only 65% power would be required to
get the aircraft to skid with the brakes ON. We know that Reid
brought the power to 80% prior to brake release. He immediately
released the brakes and applied full takeoff power.
It seems likely that the aircraft actually
started to skid when power was brought up above 65%. With the smooth
application of power by Reid, this skidding was probably not
detectable until he had already released the brakes and the crew
would then believe themselves to be accelerating normally. At this
point, with the wheels already skidding on the water-covered ice,
releasing the brakes would not be sufficient to get the wheels to
The only way to have prevented this would have
been to not use braking, which would have increased the takeoff roll
length, or to have not stopped on the runway, which would have
required an immediate clearance by ATC.