Flight Training - February 2014 - 23

ACCIDENT REPORT

Dan Namowitz
THE AVERAGE snowflake falls at a
speed of 3.1 miles per hour.

COLD AND CALCULATING

SLIPPERY CONDITIONS CAN CATCH YOU

he sun is dazzling, and a brisk breeze is snapping the windsock as you head for the airport the day after a winter storm
moved through the area. It's been a few weeks since the holiday interval created any opportunities for a cross-country or
even just some simple practice sessions. So now, you're headed to the
airport to fulfill that annual resolution to fly more.
A certain fine edge of your flying skills
has been dulled by your sporadic flying opportunities. Landings inevitably
unmask a slippage of skill more blatantly
than other elements of piloting. Passengers-who may not have been aware that
your zigzagging track down the localizer
course, or your one-dot-low positioning
on the glideslope, wasn't a great performance-are certain to notice if your
touchdown seems unduly interesting.
You know that a slightly clunky arrival
is acceptable if the wind is high and
gusting. But don't confuse making a firm
landing under lively conditions with a
failure to exercise precise control. Lapses
you can get by with in warm-weather
flying can put you on a very slippery slope
in winter.
Suppose you recall that the last time
you landed in a gusty left crosswind, you
had given yourself good marks for aggressive rudder work to keep the aircraft's
nose (longitudinal axis) aligned with its
direction of motion, but you were disappointed to find that your aircraft had
drifted half a wingspan downwind of the
runway centerline during the flare. Were
you so fixated on tracking straight ahead
that you failed to control bank angle to
compensate for downwind drift?
Unsatisfied with that outcome, you gave
it the gun and flew another pattern. This
time during the landing you kept the aircraft perfectly positioned over the runway
centerline, but a squeak of pique from the
landing gear served to remind that even a
PLUS Hone your aeronautical
decision-making skills in this
Air Safety Institute course.

slight crab during touchdown is too much.
Ah, well, it was only technical imprecision, not a true safety concern...right?
Not this time of year.
Snow melts rapidly on pavement under
this bright sun-and the crew does a great
job of scraping the surface bare-but
here and there an icy patch remains. And
although daylight is increasing, the sun
need not be beneath the horizon before
temperatures plummet, the midday melting ceases, and wet patches harden into
traps for a sliding wheel. Under such scenarios, the adverse effects of drift or crab
errors are greatly magnified. Throw in
some lingering post-frontal snow squalls
and variable wind directions and you
have a tricky but common set of winter
conditions.
It's not always the icy patch that gets
you; sometimes it's the bare spot waiting
just beyond-especially if other conditions have already teamed up to elevate
the risk factor. A pilot landing a twinengine Piper PA-31-350 in Dutch Harbor,
Alaska, on February 16, 2013, "reported
that during the flight the weather began
changing and he arrived at the destination airport in unforecast deteriorating
weather conditions," said an online
National Transportation Safety Board

Safety Quiz: Ice Flight
Take a flight up the East Coast in an IFRequipped Cessna 172RG and consider what
you would do when faced with the icing
conditions on this flight in this Air Safety
Institute online Safety Quiz (www.aopa.
org/Education/Safety-Quizzes).

accident report. "Unable to circle to land
into the wind, the pilot elected to land on
Runway 12 with a gusting quartering right
tailwind. During the landing roll, a wind
gust pushed the nose of the airplane to
the right, and the airplane began to slide
momentarily on an icy patch on the runway. While sliding sideways, the left main
landing gear contacted bare pavement,
which resulted in the collapse of the left
main landing gear."
Winds were reported from "339 degrees
at 26 knots, with gusts to 35 knots." The
NTSB added that "according to the pilot
operating handbook for the accident
airplane, the maximum demonstrated
crosswind component for the airplane is
20 knots, and a plot of the current wind
conditions at the time of the accident
showed that the crosswind component
for the accident landing was 30 knots, 10
knots above the maximum demonstrated
component."
Perhaps you have heard it pointed out
during hangar-flying sessions that a demonstrated crosswind velocity is developed
in flight testing but does not constitute a
limiting value. That fine distinction did
not stop the NTSB from assigning as probable accident cause "the pilot's decision to
land in wind conditions that exceeded the
airplane's demonstrated crosswind capability, which resulted in a loss of airplane
control during the landing roll."
Even if you have landed on slippery
surfaces many times without mishaps, and
have tackled crosswinds near published
(if not limiting) values with ease, think of
the combined effect of those two winter hazards on an aircraft as if the wind
were higher, the aircraft's responsiveness
diminished, and the time available to
make the save almost nil.
Then go out and practice.
Dan Namowitz is an aviation writer and flight
instructor. He has been a pilot since 1985 and an
instructor since 1990.

FEBRUARY 2014 FLIGHT TRAINING

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http://flash.aopa.org/asf/decisionmaking/dtrt.cfm? http://www.aopa.org/Education/Safety-Quizzes http://www.aopa.org/Education/Safety-Quizzes

Flight Training - February 2014

Table of Contents for the Digital Edition of Flight Training - February 2014