This is the 8th in a series of “12 Days of
Christmas” gifts for pilots. You can find links to the previous seven articles
on the www.aviationchatter.com web
site. Special thanks to Vincent at www.plasticpilot.net
for suggesting this series.
The Day 8 gift is something all pilots can give themselves: Get to know your GPS thoroughly to
enhance your flight safety! Instrument flying is a “bet the ranch”
proposition. If you don’t do it well, it can hasten your demise. Modern GPS
receivers increase your potential
capability, but require increasing amounts of training and practice to get the
most from them. That puts the onus on pilots to do more self-study and
training. Flight instructors can no longer just teach the same things they’ve
always taught. Now they need to get smart on the sophisticated GPS systems
found in modern aircraft.
Here’s an excerpt from my new Max Trescott’s GPS & WAAS
Instrument Flying Handbook.
Three Ways to Fly an
Approach
“Most instrument approaches can be flown in either of two ways:
via own navigation, also called pilot navigation, which often involves a
procedure turn and via radar vectors from ATC. In addition, many GPS approaches
can be flown a third way, which involves being cleared directly to the
intermediate fix of the approach. We’ll discuss that third option in detail in
Chapter 10.
“Own navigation is used in the real world when aircraft are below
radar coverage and ATC can neither see nor vector the aircraft. In that case,
aircraft can safely fly the approach on their own, provided they fly the
instrument approach exactly as published. This is usually more work than flying
an approach via vectors and often includes flying away from the airport before
turning around using a procedure turn to fly inbound to the airport. Own
navigation is also used heavily in training, so that pilots become familiar
with its intricacies.
“Flying via vectors is the preferred way to fly an approach, since
it’s less work for the pilot, though it requires more work from the controller
who monitors your progress via radar and issues a series of vectors or turns
that line you up for the approach. For an approach via vectors, envision a
straight line, extending a number of miles from the airport, which is often,
but not always, aligned with the runway’s extended centerline. The controller
turns you onto the line and you then follow it, using GPS or other equipment,
to the airport. When the chips are down, e.g., you’re tired, low on fuel or the
weather is rotten, request vectors, preferably to an ILS or LPV approach, since
it will require the least amount of work on your part and give you the greatest
chance of successfully flying an approach….
“…The third method, new in 2006, is that ATC can clear you direct to
the intermediate fix and allow you to turn onto the intermediate segment
without flying any course reversal charted at the IF (intermediate fix). This
is permitted if your IFR flight plan indicates an RNAV equipment suffix. When
doing this, the controller is supposed to provide radar monitoring to the IF
and advise you, at least 5 miles from the fix, to expect clearance direct to the
IF. This allows you time to program your GPS to fly to the intermediate fix.
The controller must also assign an altitude to maintain until the IF and ensure
that your aircraft is on a course that will intercept the intermediate segment
at an angle not greater than 90° and is at an altitude that will permit a
normal descent from the intermediate fix to the FAF. Information about this new
option is in section 5-4-7 of the Aeronautical Information Manual.”
The book also teaches:
• The myth of “activating the approach” and why you never need to
do it
• Why your autopilot may fail to couple to an ILS glide slope
• Details on the new minimums: LPV, LNAV/VNAV, LNAV, LNAV+V, and
LP.
• When to load versus to activate an instrument approach
and dozens of other tips from top Master CFIs.
I have it in my library. Its a great approach to the "new" world of GPS and glass cockpit based instrument flying. This is the proverbial "missing manual" to your avionics.
Posted by: Patrick Flannigan | December 11, 2009 at 02:49 AM