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often uses the floor/ceiling altitudes to route IFR air
carrier flights transitioning to or from the airport
terminal area. Safer practice is to maintain an
appropriate VFR altitude buffer between the aircraft and
Class B floor/ceiling altitudes.
Code/A Alert
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Helicopter Connections
CALLBACK has published stories in past issues about
aircraft that took off with a tow bar or tail stand
attached. Here’s a similar report filed by the pilot of a
helicopter air ambulance flight:

I was going to move the aircraft to airport so it could be
hangared from the approaching severe thunderstorm. The
aircraft has several orange electrical cords used to power
the medical equipment and cellular telephone. I walked
around the aircraft, untied the rotor blade and observed the
orange cords lying on the ground. I started the aircraft and
took off for the airport and returned to the hospital due to
the thunderstorm. I missed one of the cords plugged into
the aircraft and it became tangled in power lines on
approach (over) to the hospital. No damage to the aircraft
occurred.
The incident was caused by the urgency to move the
aircraft due to severe weather…. I also started the aircraft
without the assistance of the other crew members, as they
were busy. All of these factors caused me to miss the cord
going in the right rear door of the aircraft.
Telephone Line Flexes Muscle
Professional helicopter pilots spend many hours honing
the skills needed to perform confined area landings and
takeoffs. These skills are crucial to the completion of
many helicopter missions. Pilots in a multi-crew
helicopter operation often used ground observers to help
judge clearance from wires and other hazards to spinning
rotor blades. But at times even this precaution is not
enough to prevent an incident, as the pilot of this aerial
photography mission discovered.

The mission was to take up a photographer to take
aerial pictures of the scene of a shooting. A landing was to
be made near the incident to pick up the photographer. The
area was an urban environment with numerous wires.
After an aerial reconnaissance was completed, a landing
was made to a suitable spot.
After landing, the pilot got out of the helicopter to better
inspect the wires he would need to negotiate on departure.
There was a single strand wire crossing North to South
between two telephone poles. The departure was to the West.
Below the wire was a chain link fence approximately 12 feet
high. With the way the helicopter was configured, the pilot
was not sure he would be able to clear the wire on
departure. He decided the best option would be to fly slowly
over the fence and under the wire. Beyond the wire the
departure area was clear. The estimated distance between
the top of the fence and the wire was 20+ feet. The wind
was out of the West at 10 knots.
The observer was left on the ground so the load would be
lighter. The pilot brought the helicopter to a high hover
and slowly moved over
the fence. The pilot
looked up to check the
clearance of the wire
again and it looked good, so he proceeded forward. A loud
snapping sound was heard and the aircraft began to
shudder. The pilot continued forward and brought the
helicopter to a landing beyond the fence.
The observer that was left on the ground said that as the
helicopter moved over the fence it appeared to have plenty of
clearance. Then as the rotor system was just about centered
under the wire, the wire began to oscillate up and down
eventually coming down far enough to strike the top of the
rotor system… The pilot simply did not imagine at the time
that the wire could be affected to that extent by the rotor
wash.
After the incident, the pilot talked to other pilots in the unit
about the incident. Most said they would have done the
same thing and had never considered that something of
this nature could happen. The exception was a military
trained pilot who said that when the military trains for
under-wire flights, the minimum clearance is 200 feet.
Frequency Update
The November 2000 CALLBACK (#255) included an
article on wake vortex hazard at cruise altitudes.
This article cited 131.8 MHz as the aircraft-toaircraft
communications frequency used on North
Atlantic routes in conjunction with Reduced Vertical
Separation Minimum (RVSM) air traffic procedures.
We heard back from several alert readers that the
131.8 MHz frequency is no longer in use.
✍ I sometimes fly in [North Atlantic] airspace with
　
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