ROBERT N. ROSSIER
BETTER PILOT / STICK & RUDDER
Descent
Planning
Preparing to land
WHILE CRUISE IS ARGUABLY the safest phase of flight, the situation
changes as we head toward landing. As our workload slowly
increases, our focus begins to narrow, and we can easily overlook details that could lead to a dangerous situation. Statistics
reveal that an accident is four times as likely during descent as
it is in cruise flight. With proper attention to the details of
descent planning, we can more easily manage the demands of
the descent and increase the chances of a safe arrival.
THE BASICS
On the surface, it would seem that
descent planning is primarily a matter of
mathematics. For many light aircraft, we
might plan a comfortable 500-foot-per
minute descent. Reducing power
gradually minimizes the risk of shock-cooling the engine; that is, allowing
cylinders to cool so fast that they crack.
Also, 500 feet per minute is not likely to
cause passengers’ ears to pop
uncomfortably. And finally, 500 feet per
minute makes for easy arithmetic.
That’s 1,000 feet down for every two
minutes’ flying time. To translate that
into miles from the destination, check the
groundspeed. At 120 knots, for example,
you’re covering two nautical miles (nm)
per minute. So you should plan to start
your descent four nm out for every 1,000
feet you are above pattern altitude.
Example: Let’s say we’re cruising
westbound at 6,500 feet mean sea level
toward an airport with a pattern altitude
of 1,500 feet. Simple subtraction reveals
