Business Aviation Insider - September/October 2013 (PREVIEW) - (Page 11)
Morgan Anderson Photography
dealing with Contaminated runways
When winter arrives, and airport runways
are subject to the effects of the cold
weather, safety experts agree on what
operators need to do: Be aware of runway
conditions; develop a plan appropriate for
those conditions; execute that plan.
These three critical steps are required to
successfully negotiate runways contaminated with ice, slush, snow or water.
Reports from the NTSB and the Aviation Safety Reporting System show that
pilots' failure to sufficiently adjust for
contaminated runways contributes to a
disproportionate percentage of runway
accidents, said J.R. Russell, a founder and
principal of ProActive Safety Systems Inc.
“Often the biggest challenge is getting
current, accurate runway-condition information when you most need it,” explained
Russell, an air transport-rated pilot who
also serves on NBAA’s Safety Committee.
“Knowing conditions now is the most
critical piece of knowledge you can have
before starting an approach to a challenging runway,” said Russell, who added, “No
matter what the pre-departure weather
briefing said, conditions probably changed
while you were en route. You must know
how to fly appropriate to conditions – then
Runway surface friction, expressed as an
“Mu” number, is directly proportional to
the braking action available to an aircraft,
with 100 being the maximum. To simplify
this formula, just remember: complications
increase as friction decreases.
Sometimes the contaminant is little
more than a thin sheet of liquid water. Or
it can be as complicated as ice ridges or
ruts alternating with patches of bare pavement. Either way, each condition affects
takeoffs and landings differently. Russell
explained, for example, that hydroplaning on standing water is usually more of a
problem on landing than takeoff.
“Different aircraft come with different
instructions on handling runway contamination,” Russell continued. “You must
know what the manufacturer says is
best for the conditions – and know those
conditions’ impact on performance.”
Avoiding Avoidable Accidents
“Managing contaminated runways is an
exercise in threats and errors management,” Russell said. “Assess the threat,
manage that threat and avoid errors that
can become an accident.”
Failure to adjust for a contaminated runway’s decreased friction is
the common factor in winter-runway
accidents. “Sometimes pilots seem to
not recognize the significance of friction measurements and braking-action
reports,” observed NBAA Operations
Service Group Specialist Brian Koester.
Accidents and incidents involving
winter-contaminated runways largely stem
from pilot failures to control speed, landing spot or both. Landing too fast or too
long sets up runway-overrun accidents;
failure to adjust for icy pavement contributes to aircraft sliding off runways in
strong winds or in turns.
Runway contaminants also can create
mechanical issues that contribute to other
failures. For example, wheels can freeze
when slush accumulates on them during
takeoff, which can cause them to freeze in
the wheel wells. When wheels won't turn,
the plane slides until they break free.
“Contaminated runways require the
same level of awareness, knowledge
and disciplined action as instrument
operations because runways often
stay contaminated long after weather
improves,” Koester explained.
Russell concurred: “You can't adjust for
conditions without knowing those conditions before landing. So we must know
current runway conditions; understand the
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