Transitioning to the Autopilot

Document Sample
Transitioning to the Autopilot Powered By Docstoc
					                             Transitioning to the Autopilot

An autopilot is a valuable assistant in flying single-pilot IFR. With the autopilot engaged,
you are better able to deal with ATC and watch for traffic. Some pilots, my Dad being
one, would argue that I use it too much. He would not even install one in his aircraft. His
position was a reasoned one. He accumulated over 6,000 hours during his 39 years of
flying, all of which was private and mostly in Barons, and he constantly studied flying
issues. He believed that he needed the hands-on practice to keep proficient. We are at
opposite ends of what is a philosophical argument. If you lean toward my side of the
debate, you may find the procedure I use for transitioning to the autopilot helpful.

The Problem in Transitioning to the Autopilot
Why is transitioning from hand-flying to autopilot such a big deal? Can’t you just turn it
on and let it fly the aircraft? The answer would be yes if it were not for the fact that you
first need to tell the autopilot what you want it to do regarding pitch, roll, heading and
altitude. Getting this setup right is the challenge. Autopilot setup is deceptively complex
until you’ve done it many times successfully and stay practiced at it. Pushing buttons to
see what happens doesn’t cut it when you’re busy and not wanting distractions.

The transition from hands-on flying to autopilot should be smooth, i.e. the autopilot,
when engaged, should mirror the hands-on attitude and proceed to take the aircraft where
you intend. Usually this is to continue on the current heading at the current climb rate. It
sounds simple, but unless you are quite proficient in working your autopilot, the odds are
good that you won’t get it right on the first try.

The first opportunity to put the autopilot to work is on departure. This is a busy time in
the cockpit and an extra hand is welcome. But it’s not a situation where you want
surprises. Things can get exciting in the departure environment when you’re in a climb,
busy with ATC and you engage the autopilot only to find it want to take you in another

Operation of a three-axis autopilot like the Bendix/King KFC 225 is not totally intuitive.
It’s easy to inadvertently set up a mode that is different from what you intend. The KFC
225 user guide and POH supplement are very explicit in describing the functions of the
various controls. Unfortunately these descriptions are not easy to follow and easily

On departure I like to hand-fly until I reach 1000 ft AGL, then engage the autopilot in
Heading and Altitude Preselect mode. There are two frustrating situations that, until I
developed my current procedure, I regularly encountered when engaging the autopilot on
departure because I had set it up wrong: (1) the aircraft stops climbing, and/or (2) the
aircraft climbs right through the assigned altitude. These conditions are not particularly
hazardous provided you maintain your instrument scan and stay ahead of the airplane.
They just add extra, unnecessary workload when you least appreciate it.

Presetting the Autopilot
After considerable trial and error, I have developed a procedure that accommodates my
level of competence. It involves presetting the autopilot prior to takeoff. Note that this
procedure is for the three-axis Bendix/King KFC 225, which has Altitude Preselect and
Flight Director capability (Figure 1). The procedure may need to be modified for other
makes and models of autopilot. Here is the procedure I use.

                                Figure 1: KFC 225 Autopilot System

My Before Takeoff checklist includes the following steps:
      1. AP Test OK
      2. Set assigned Departure Altitude in Altitude Preselect window
      3. Select ARM
      4. Select VS (Vertical Speed)
      5. Set Vertical Speed to + 900 fpm using UP/DN
      6. Set Bug on the HSI to assigned Departure Heading

With the above settings, the autopilot is programmed for the initial departure clearance
and is ready to take over when engaged. The Flight Director function is activated and the
command bars on the attitude indicator indicate the required pitch and bank once airborne
for a straight out departure. Do not pre-select HDG. If the initial heading is other than the
runway heading, the command bars will be tilted indicating a climbing turn and you have
to ignore this confusing indication on your AI until you are ready to commence the turn.

At 400 ft AGL, activate FD command bars for climbing turn to departure heading by:
        1. Select HDG

At 1000 ft AGL, engage the autopilot by:
       1. Select AP

The autopilot will now track the heading set on the HSI bug and establish a climb of 900
fpm. It will also level off at the altitude set in the Altitude Preselect window. The 900
fpm initial rate of climb is a best guess that works pretty well with my Bonanza. I adjust
the rate of climb as needed using the UP/DN buttons to maintain a cruise climb of 110
KIAS. You could activate the autopilot at 400 ft AGL and not hand-fly the initial turn to
the assigned departure heading. However, the Bonanza climbs to 1000 ft AGL quickly
and I feel more comfortable hand-flying through this initial stage. If something goes
wrong when activating the autopilot, I want to be at a safe altitude, i.e. over 1000 ft AGL.

A procedure I tried and discarded was to select Go Around (GA) prior to takeoff. This
positions the Flight Director command bars for straight ahead climb, however it also
clears any preset conditions in the autopilot. You are now faced with the need to do all
the autopilot setup on the fly during departure.

A Final Word on Autopilot Use
My philosophy regarding use of the autopilot is to make full use of it to reduce my
workload. I practice mostly without it and it's about 50:50 whether I fly approaches in
actual IMC by hand or with the autopilot. I don't have a preference for flying coupled
approaches unless the weather is pushing my personal minimums. In this case I'll opt for
the autopilot for the extra margin of safety. Since autopilots can and do fail, I constantly
monitor its performance and particularly watch for runaway trim. I personally have not
experienced the problem, but I personally know a pilot who has had it happen three
times. He assures me it is a scary situation when it happens.

Peter Cassidy


Shared By: