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Autopilot
How do they work?
Is Autopilot Reliable?
engineeringinsider
Autopilot! You would
have heard about them a lot in the movies and in aviation documentaries.
What are they in the real
sense? Baffles many.
Autopilots, as the name
suggests, is basically a system which automates certain critical and
time-consuming process that otherwise a pilot has to pay due attention to in
real time.
Autopilots were made to
ease the stress of long flights by pilots.
In the earlier air
crafts, the airplanes had limited range and were required to fly for short
distances only.
With the growth and
development of aeronautics industry new and more sophisticated air crafts
with the capability to fly for long distances and times were created.
This required the pilots
to pay additional attention to flight systems for a longer period of time hence
adding a huge professional toll on the stress levels of the pilots.
A system was required
that would take some stress off the pilot’s shoulders and make them
operationally more efficient. Hence the birth of autopilot was marked.
Earlier autopilots were
simple systems which would maintain a fixed level and altitude for the aircraft
so that the pilot could pay attention to other flight systems.
Auto
Pilots are of three types:
Single
axis autopilot: This
type of autopilot can only automate the roll axis of the aircraft. They keep
the level of the wing constant hence stabilizing the altitude and direction of
the aircraft. They keep the aircraft in a single line of motion and cannot
handle a complex flight path.
Two
Axis Autopilot:
A two-axis autopilot is
somewhat more utilitarian when compared to a single axis autopilot as it can
control both the pitch and roll of the aircraft.
It can also be connected to an onboard radio
guidance system and can efficiently fly the aircraft shortly after and before
landing. They cannot aid a pilot in landing and take.
Three-axis autopilot:
A three-axis autopilot
system can control the pitch, roll, and yaw of the aircraft in real time and is
used for long-haul aircraft which fly complex routes and have a greater flight
time.
In a modern aircraft
chances of having a three-axis autopilot are great. Three-axis autopilot
system can control most of the stages of a flight and is an integral part of
overall flight management system.
This can also be termed
as the modern autopilot system as its function is divided into many stages.
A
three-stage autopilot system has its functionality divided into many
stages, the stages are taxi stage, take off stage, climb stage, cruise stage,
descent stage, and landing stage.
A pilot has the
assistance of a sophisticated computer and sensors driven system in every stage
of his work.
It must be noted that
autopilots are only designed to assist pilots in performing their duties and in
no sense can replace completely any part of work that goes into flying an
aircraft.
Sophisticated computer
software and systems are installed onboard an aircraft which can be aware of
its current position, altitude, bearing and velocity and even more information
that might be required for a safe flight.
Modern autopilots can
also control the thrusts of the aircraft to optimize the speed of the aircraft
as required for a safe journey.
The autopilot can also be
guided by ground-based instrumental landing systems for an instrumental landing
in case of harsh weather conditions.
Modern autopilots and
completely guide an aircraft from take off to landing at the destination a lot
of stress away from pilots shoulders.
Working
Modern autopilot systems
are very complex pieces of machinery. Their working is a bit complex.
The onboard computer of
an aircraft is laden with sensors which continuously feed the autopilot system
with information on engine rpm, altitude, bearing, heading and even climatic
conditions along with distance to be traveled and available fuel.
Modern autopilots are
then using a complex algorithm compute the best way for the flight.
In case of poor weather
conditions with extremely low or no visibility a specialized system in the
autopilot called instrumental landing system or auto-land is used.
Auto-land system relies
heavily on radar altimeter as there could be zero error in calculating the
distance to land from the aircraft.
A radio-altimeter coupled
with airstrip ILS beacon has to be in perfect synergy in order to achieve an
error-free ILS guided landing.
The land beacon of
ILS bounces off signals to the aircraft system verifying that the approach
taken by the aircraft’s onboard system is correct. Once this is achieved the
onboard system calculates rest of the perimeters and lands the aircraft.
However, this system does
not eliminate the pilots’ role completely as its response rate to other
conditions like wind speed and wind shear is limited and would require pilots’
attention for a safe landing.
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