Global Aviator May 2018 / Vol. 10 / No. 5 13
The view out of a Robinson Helicopter,
the world's best selling helicopter!hours of frantic searching, everyone’s
worst fears were realised – all 256
people on board had perished.
The question on everyone’s mind
now was: What could have brought
down the plane so shortly after take-
off and cause this horrific accident?
The investigation into the crash of
Arrow Air Flight 1285 would provide
more questions than answers and also
lead the CASB (Canadian Aviation
Safety Board) to issue two very different
opinions on what caused the crash.
The “majority” of the board “believes”
that the most probably cause for the
accident was ice contamination, while
a few other people had a dissenting
opinion that an in-flight fire might
be responsible for the crash.
We will take a quick closer look
at each of these opinions and maybe
by the end of the article you can
decide for yourself what you think
caused the accident of Flight 1285.
Icing
In reality only a small amount of ice
is needed to bring down an airplane,
but why is it then that other pilots
flying into and from Gander did not
have any ice related problems? The
crew of a British Aerospace VC-10 did
not report any significant icing and
therefore did not de-ice their plane
before take-off. A Boeing 737 aircraft
which departed about 30 minutes
before the accident did indeed decide
to de-ice the plane as precipitation in
the form of very light freezing drizzle
and light snow was reported.
From the information above we
now know that de-icing facilities were
available in Gander. Could the crew
of Flight 1285 have made a serious
error by not de-icing the plane? To
minimize the hazards associated with
ice contamination and also to comply
with the “clean aircraft concept”; it
is common practice in the aviation
industry to de-ice an airplane before
take-off when weather conditions are
favourable for drizzle, rain and snow.
According to the operating manual
of the DC-8, it states the following:
- Snow, ice and frost removal
“Snow removal from the control surfaces
must be complete to ensure proper
balance and travel. Control surface
movements can be seriously affected by
freezing of hinge points. Aircraft should
not be dispatched unless a careful visual
check has been made of aircraft wings,
control surfaces and hinge points, and it
has been definitely determined that frost
or snow deposits are cleared from these
areas. At any time de-icing is performed,
all slush or snow accumulations will
be removed from all areas by use
of glycol de-icing equipment.”Before the mid ninety-eighties, little
was known about the aerodynamic
impact of very thin ice accumulation.
Yes, we know the flight engineer did
his inspection before the flight took off,
but he was probably looking for large
build-up of ice that would make the
plane significantly heavier, not thin
coatings on top of the wing surface. The
leading edge portion of the wing is the
most sensitive to ice contamination. But
looking back at the other two flights that
departed Gander without problems, it is
sure to say that ice alone could not have
caused the crash. To normally find out
what caused an accident, investigators
take a look at the CVR (Cockpit Voice
Recorder) and the FDR (Flight Data
Recorder). But in this case these twopieces of equipment could not really
help with the investigation. The aircraft
also had an older model of the black box.
The older models would engrave data
on a slow moving roll stainless steel foil.
Although fire resistant, they could only
record about four flight parameters,
such as airspeed and altitude.
The CVR tape was found to
be broken in two places, but apart
from the breaks it was undamaged.
Unfortunately it did not record any of
the conversations between the crew. A
closer look at the flight data does reveal
that the distance needed to get to take-
off speed was longer than planned for- more than 1000 feet. Why did it take
so long? An aircraft will not lift-off until
the lift produced exceeds the aircraft
weight. The effect that ice has on an
aircraft is that it causes a reduced lift.
So the longer than normal take-
off supports the theory that ice on the
wings did play a role in the crash.
Weight
Focus shifted to the weight of the
aircraft – could this also have
contributed to the slow take-off?
In the operating manual under
the Weight and Balance Section it
identifies that the standard average adult
passenger weight, including five pounds
of carry-on baggage as 170 pounds.
The section also states that
when large groups of passengers are
carried whose average weight does
not conform to the normal standard
weight, their actual passenger weightRight: An aerial view of the crash site
of flight 1285 just after take-off.The CVR tape was
found to be broken in
two places, but apart
from the breaks it
was undamaged