AOPA Turbine Pilot Magazine - November 2021 - 87

RUDDER & WRENCH
ON INSTRUMENTS /
Low-IMC alerts
Anticipating challenges on final
BY THOMAS A. HORNE
precision approaches have missed
approach points defined by published
decision heights or decision altitudes,
and most approaches supplemented with
DME information post their minimums
augmented with DME distances. But
ILS and many nonprecision approaches
are published with elapsed times from
their final approach fixes to their missed
approach points. The times are based on
the airplane's groundspeed, and on many
nonprecision approaches (those without
vertical guidance) it's the elapsed
time that dictates the missed approach
point. Forget to start timing at the final
approach fix-and adjust the time for
wind effects-and on many nonprecision
approaches you won't know when to execute
a missed approach.
Speaking of time, it's equally imporF
LY I NG INS TRUMENT APPROACHES in
actual instrument conditions is always
demanding, but when the weather is low
IFR (ceiling less than 500 feet, and/or visibility
less than one mile), seemingly small
blunders can have big consequences.
When ceilings and visibilities are well
above minimums, there's often enough
altitude and time to allow a larger margin
of error. That's not often the case when
you're on the final approach course, close
to the ground, and still in clouds.
Not anticipating the effects of a crab
is one such problem. You may have listened
to the ATIS, ASOS, or AWOS back at
the initial approach fix-and even copied
it down-so you know the wind direction
and the approach runway in use.
You know if a crosswind component is a
factor, so you're mentally prepared for a
crosswind landing technique. On the trip
down the final approach course you make
the proper heading corrections to keep on
track, adjusting for any crosswind effects.
But when you break out of the clouds,
spotting the runway may be a challenge.
Depending on your crosswind correction
angle, the nose of the airplane may
be pointing well away from the airport.
You're still on course, but need to look
around to find the runway, then maneuver
in preparation for landing. And at this low
altitude, it isn't exactly the best time to
make steep banks. Especially if you hadn't
mentally prepared for it. That goes double
if you're flying at night. The runway lights
may be far from the view straight ahead.
Crabbing and slipping prior to touchdown
is common in crosswind VFR operations.
Coming out of a big crab angle on a long
final in IMC is another matter.
Forgetting to time your approaches
can bring other surprises in low instrument
meteorological conditions. Sure,
tant to keep track of your flight time. You
calculated an estimated time en route
(ETE) on your flight plan, and ATC will
rely on that in the event communications
are lost. Should that happen, any expect
further clearance (EFC) times will depend
on your estimated time of arrival (ETA) at
your destination airport, which is based
on your flight-planned ETE. Absent an
EFC time, if your last clearance limit
was an approach fix, you'd leave it at
your ETA. If the last clearance limit you
received wasn't to an approach fix and
you lost communications, then the regulations
say to fly to one and then begin
your descent and approach at your ETA.
Meanwhile, ATC is keeping other traffic
at bay while you proceed to the airport.
For complete missed approach procedure
details, consult FAR 91.185(c).
And all of this depends on the ETE
you filed. That means starting the clock
at takeoff and monitoring your ETE as
you fly. Did you ever forget this step? I'm
betting it's pretty common, so let's hope
AOPA PILOT / November 2021
87
CHARLES FLOYD
AOPA Turbine Pilot Magazine - November 2021

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