Flight Training - August 2019 - 10

FLYING CARPET BY GREG BROWN

When GREG BROWN learned
instrument flying, the toughest
challenge was visualizing your
position. Nowadays, it's programming
the avionics.
GregBrownFlyingCarpet.com

OH, THE GLORY

Rarely do light airplane pilots get to outfly the airlines, but it
does occasionally happen.
A dozen years ago, the Flying Carpet sustained a spate of inflight voltage
regulator failures. This device meters electricity generated by the alternator to
meet the airplane's ongoing electrical needs and keep the battery charged. It
also protects the electrical system against spikes or shorts that could damage
electrical components. Every few months our latest voltage regulator would fail
in flight, disabling the aircraft's charging system and sending us scrambling for
a mechanic. Sometimes it could be temporarily reset by cycling the alternator
switch, but usually not. Of course these failures always occurred at inopportune times, and caused lots of "what-if " stress every time we launched on a
cross-country flight. Yet the intermittency stymied our mechanics ability to
identify the cause.
Then one day, a savvy avionics tech at Falcon Field (FFZ) asked if I could hear
our original-equipment flashing beacon cycling on and off through my headset.
When I answered yes, he asked if those beacon pulses also presented via the
ammeter needle. They did. It turns out that with age, the power supply units for old
flashing beacons can internally deteriorate, drawing increasing electrical current as
the circuitry fails. Testing revealed that our beacon was drawing so much current
with each flash, that over time it was causing each successive voltage regulator to
disconnect the charging system and fail. Installing a new low-power LED beacon
solved the problem, but it would take months of trouble-free operation before we
could fully believe it.
10 FLIGHT TRAINING AUGUST 2019

Jean and I launched homeward from
FFZ that day flashing our bright-andshiny new beacon, arriving to rare IFR
weather in Flagstaff. For those not familiar,
cloud-flying pilots navigate specific published instrument approach procedures to
guide them safely from cruising altitude to
landing. In general, the more accurate the
approach, the lower airplanes are allowed
to descend. If the pilot can see the runway
upon reaching the minimum legal altitude
for that approach, he or she proceeds to
land. If not, the pilot must execute a specific missed approach procedure, and, in
most cases, land elsewhere.
On this day, Flagstaff Pulliam Airport
reported a 600-foot overcast with good
visibility underneath. The airport features
three approaches with minimums well
below that. Although the ILS (groundbased instrument landing system) was
out of service for runway lengthening, I
anticipated no difficulty descending out
of the clouds on one of two precision GPS
instrument approaches to land. However,
as we steered for our assigned initial
approach fix, the regional airliner ahead
of us canceled its approach request and
diverted back to Phoenix. Had something changed to affect our safe arrival?
Alarmed, I queried Flagstaff Tower.
"With the ILS out of service, the ceiling is too low for the airliner to get in,"
came the reply. It had never occurred to
me that an airliner might not be equipped
with approach GPS, so widely installed
in light aircraft. Without it, the lowest
remaining VOR approach available to the
airline pilots featured 800-foot minimums, still in the clouds. Therefore, they
had to divert.
Our decades-old Flying Carpet, however, was fitted with avionics capable of
precision-like GPS approaches to 250 feet
above the ground. So while the airliner
retreated to Phoenix, we easily cleared
the clouds to land. Afterward I'd learn
that few airline aircraft regardless of size
were then equipped with GPS approach
capability-still the case today with many
older jetliners.
"You have a heckuva bright beacon,"
commented the tower controller as we
taxied in. "Even in daylight I spotted it
the moment you broke out of the clouds."
But my mind was elsewhere. Oh, the
glory, that Jean should be along to witness my heroic approach and touchdown,
on a day when airliners couldn't land. FT

http://www.GregBrownFlyingCarpet.com

Flight Training - August 2019

Table of Contents for the Digital Edition of Flight Training - August 2019