Helicopter Age, Safety Level, Flight Path
& Structure - Q&A
Q: Was this a case of operational use being made of
an obsolete model?
A: "Yassour" is the Israel Air Force designation for
the US Sikorsky CH-53 assault air transport
helicopter developed 30 years ago for the Marines,
and which arrived in Israel toward the end of the
War of Attrition in the late ‘sixties. The original
model was upgraded over the years at the parent
plant, and the "Yassour 2000" helicopters that
crashed last night were also equipped with Israeli
improvements.
Model age is not necessarily the same as aircraft age
and the helicopters, on the face of it, do not seem to
have been very old. This helicopter is actually an
Israeli development, based on local experience, and
it is equipped with Israeli-manufactured avionics
devices. The helicopter has proven daytime and
night-time all-weather reliability and
manoeuvrability.
Q: In their 28 years of service in the IAF, Yassour
helicopters have been involved in 12 crash
disasters. Does this not characterise their safety
level?
A: Reliability and safety level are not measured by
accident statistics but in relation to the mass of
operational sorties and, in training, in terms of flight
hours, load and tasks. The accident percentage may
be assumed to be minimal in relation to quantity.
Q: What causes helicopter accidents?
A: A helicopter usually flies at low altitude. That is
its operational advantage, enabling it to steal
unobserved into enemy territory, keeping close to
the ground, or moving along water courses, in
geographical conditions that prevent early detection
on radar screens. But this is also its drawback. Its
manoeuvrability is limited in case of malfunction.
Proximity to the ground also restricts recourse to
instrument flying so that the human element,
meaning the pilot’s responses, becomes, for better
or for worse, a key element.
Q: What lessons are learned from an accident of this
sort?
A: For example: The number of passengers per sortie
should be reduced. Each of the helicopters that
crashed last night was flying only 35 soldiers in
addition to the air crew, and that was not by chance.
Q: Why did the helicopters have to fly over a
populated area?
A: Flight paths, especially in the circumstances
prevailing last night, have a more or less regular
format. The helicopters took off from the
Mahanayim airfield near Rosh Pina, heading for
south Lebanon, and the shortest and quickest route
necessarily passed over the Galilee Panhandle. This
area is relatively densely populated. It is not one in
which a helicopter can manoeuvre between the
populated settlement areas and the farming areas.
The advantage of an ordinary night flight over an
area of this sort is that the settlement lights make
navigation easy.
Q: The accident was reportedly caused by a
nose-tail collision. Does this indicate an erroneous
flight formation?
A: It is too soon to tell. In any event, when flying in
formation, aircraft must have eye contact with one
another. In the rainy, foggy weather conditions that
obtained last night, the helicopters could not enter
Lebanon in wide formation, but had to fly in
compact, line formation. This was a combination of
circumstances calling for alertness and readiness on
the part of the pilots.