|CHAPTER 4. Automated Flight Control
Deciding When To Use the FD/Autopilot
In addition to learning how to use the FD/autopilot, you must
also learn when to use it. Since there are no definitive rules
about when an FD/autopilot should or should not be used,
you must learn to consider the benefits and disadvantages of
using the FD/autopilot in any given situation.
One of the most valuable benefits of using the FD/autopilot
is delegating the constant task of manipulating the aircraftís
controls to the equipment, which do nothing other than
comply with the pilotís programming. This allows you
more time to manage and observe the entire flight situation.
Managing the flight versus actually moving the controls
allows more time for:
- Programming. Especially when flying under IFR,
changes to a route are inevitable. Even when the
pilot is proficient in using FMS/RNAV, this task
requires focusing some attention on the programming
task. The FD/autopilot keeps the aircraft on the
programmed heading or course and altitude while the
pilot makes the necessary changes to the flight plan.
If programmed correctly, the aircraft maintains the
correct track and altitude.
- Distracting tasks/workload. Similarly, the FD/
autopilot is used to control basic aircraft movement
while the pilot focuses attention on tasks such as
reviewing charts, briefing and configuring for an
instrument approach, updating weather information,
etc. The FD/autopilot can also be a great help in
other high workload situations, such as flying in a
busy terminal area or executing a missed approach in
adverse weather conditions.
- Maintaining autopilot skills. The FD/autopilotís ability
to help manage pilot workload depends heavily on the
pilotís proficiency in using it. Regular practice with the
various autopilot functions (especially the approach
functions) is essential to develop and maintain the
knowledge and skills necessary to maximize its
- Emergencies. The FD/autopilot can be extremely
useful during an emergency. It can reduce pilot
workload and facilitate efforts to troubleshoot the
Disadvantages of using the FD/autopilot include the
- Forgetting to maintain manual flying skills. It is
important to practice flying without the FD/autopilot
often enough to maintain proficiency in basic flying
skills and the instrument cross-check and scan. One
common pitfall of advanced avionics is the pilotís
tendency to forget to maintain hard-earned skills for
instrument flight. All equipment will fail at some time.
The competent pilot is ready and prepared to make a
transition to aircraft piloting at any time.
- Turbulence. The pilotís operating handbook (POH) and FD/autopilot flight manual supplements for many
aircraft discourage or prohibit use of the autopilotís
altitude hold function during moderate or severe
turbulence. Some FD/autopilot systems may default
or disengage if certain trim or control limits are
encountered during turbulent conditions. You should
consult the flight manual to ensure the aircraft is
not operated outside specified limits. The aircraftís
flightpath and mode indications should always be
monitored to ensure what modes are active.
- Minimum altitude. Autopilots are certified for use
above a specified minimum altitude above ground
level (AGL). Some higher performance and higher
service ceiling aircraft require autopilot control above
certain airspeeds and altitudes. The flight manual
and operations manual (if any) should be consulted
to ensure that the pilot does not operate the aircraft
outside specified limits. For higher safety standards,
commercial operators must observe restrictions in
Title 14 of the Code of Federal Regulations (14 CFR) sections 121.579, 125.328, and 135.93, according to
their regulatory classification. Adoption of these limits
by private operators would add a safety margin to
flights conducted under 14 CFR part 91 regulations
in many cases.
- Possible malfunction. If at any time the pilot observes
unexpected or uncommanded behavior from the
autopilot, he or she should disengage the autopilot
until determination of the cause and its resolution.
Most autopilot systems have multiple methods of
disengagement; you should be immediately aware of
all of them. Also be aware of the methods to cancel
the FD display to avoid confusing information.