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.
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.
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.