The cockpit design of an airplane ensures that a pilot is provided with all necessary information regarding the systems of the airplane, and that he has sufficient controls available to handle all emergencies without having to leave his seat. But if we notice the numerous buttons, switches, gauges, indicators, etcetera in the cockpit; it makes us wonder, how does a pilot manage everything?
With the advancement in technology, we are now witnessing fewer gauges and less clutter within the cockpit. This is largely thanks to the Primary Flight Displays which presents information in an easy to comprehend format. Navigational aids, weather radar information, flight director systems, and several other systems are available to make the job of a pilot easier.
Similarly, the landing systems installed within the airplanes and on-ground have come a long way. So, can the airplanes now land by themselves?
Yes, airplanes can land themselves using autopilot if they have the necessary equipment installed and the pilots and aerodrome are certified for automated landings. To facilitate automated landings, major airports are equipped with an Instrument Landing System(ILS), which is a radar system showing the position of the plane relative to the runway.
While airplanes can land themselves, most of the time they are still landed manually. According to some figures, less than 1% of all landings are carried out by the autopilot. Most pilots simply believe that controlling the airplane themselves is much easier than having to monitor the autopilot during the hectic landing stages.
In some situations, such as during heavy winds, there might be limitations to the autoland system. For instance, the Boeing 737 cannot perform automated landing in crosswinds above 25 kts.
With this said, let’s look a little closer at the autopilot and its role during different stages of a flight!
Table of Contents
What Does the Autopilot Do?
Autopilot systems have existed for over a century now with the first being showcased by Sperry Corporation in 1912. This initial autopilot system was able to hold the heading and attitude of the aircraft without any pilot input.
With gradual improvements over time and the advancement in computers, we have come a long way from the first mechanical autopilot.
Nowadays, autopilot systems can navigate and fly the airplane during most of the flight without any input from the pilot. But have you ever wondered why these systems are needed?
Why Is the Autopilot Needed?
Long drives are a lot of fun, but you can easily get fatigued if you drive for a significantly long duration without any breaks.
Just think about how fatigued pilots can get while flying an airplane and constantly managing its systems.
To make their job easier and safer, modern commercial airplanes are equipped with autopilots. These systems can perform several tasks ranging from aiding the pilot to flying the plane entirely.
How Does the Autopilot Work?
Modern autopilot systems can fly an airplane in normal conditions by gathering positional and attitude information from various sensors.
These systems are instructed to follow a specific route, and based on their awareness of the aircraft position and heading, they can fly the airplane without any input from the pilots for most phases of a flight.
Let us get a bit technical here to understand how the autopilot works.
When an airplane is being manually flown, the commands given by the pilot are being implemented using feedback loops. For example, when the pilot instructs to pitch up the airplane, the flight computer will command the elevator to move until the desired pitch is achieved.
Autopilot systems consist of flight management computers that are loaded with 3D maps containing details of terrain they are expected to fly over.
Before each flight, pilots feed the data of the flight route including departure airport, destination airport, and any waypoints, into the flight management computer. During the flight, the pilot can fly manually or engage the autopilot at any given time.
With sufficient and reliable positional information from airplane’s sensors, the autopilot system calculates the altitude and heading changes needed. The flight computers then precisely calculate the changes needed in roll, pitch, or yaw and send these commands out to the flight controls.
Though the complete system is not as simple as it seems, as you see, the basics are quite easy to understand.
What Pilots Do When the Aircraft Is Flown By the Autopilot
A common misconception is that pilots are paid to just sit while autopilot does all the work.
This couldn’t be further from the truth!
Autopilot systems are dependent on the pilot’s supervision and in case of any issues or system malfunctions, pilots are required to take control and fly the airplane manually.
In fact, even after engaging the autopilot, pilots make course corrections, adjustments to various airplane systems, and communicate with the air traffic control.
Moreover, the autopilot can only be engaged after take-off, whereas, during landing, the autopilot can only be engaged considering the limitations of the airplane, pilots, and runway equipment.
Let us review what these limitations are!
Are airplane landings completely automated: Limitations of the Autopilot
Most airplane landings are not completely automated, and pilots take control of the airplane below a minimum specified height. Even though newer airplanes can land automatically, the limitations of crew training and ground equipment, in most cases, is the limiting factor.
Let us see what this ground equipment is and why it is needed!
What is the Instrument Landing System(ILS)?
The landing support equipment installed on the airport, commonly known as the Instrument Landing System (ILS) guides an airplane precisely during its final landing phase.
This equipment contains several antennas that communicate with the radio systems of an airplane to make it aware of its exact height and glideslope during landing.
The accuracy of the ILS system determines the maximum capability to host automated landings on a runway, in varying weather conditions. To determine the capability of each airport’s ILS system, they have been divided into five different categories.
These categories are defined in terms of their:
- decision height: The height at which the runway must be visible.
- runway visual requirements The distance from which runway should be visible
The more advanced the ILS system is, the lower the visual requirements.
Below the 5 categories of ILS systems are listed:
- ILS Cat I – Decision height allowed is 200ft and Runway Visual Requirements (RVR) of around 1800ft. Manual landing is required.
- ILS Cat II- Decision height of around 150ft and RVR requirement of 1200ft
- ILS Car IIIa – Decision height of around 100ft and RVR requirement of 700ft
- ILS Cat IIIb – Decision height of around 50ft and RVR requirement of 150ft-700ft
- ILS Cat IIIc – No decision height and no RVR
Based on the ILS system installed on the runway, the maximum limitations of automated landing can be decided.
In case an airplane and pilots are certified for ILS Cat IIIc landings and the equipment is available on the runway as well, a completely automated landing can be performed.
What Are the Limitations Of the Autopilot?
Autopilot systems have multiple redundancies and protections, but they come with their limitations as well. Let us go over a few of them.
- The autopilot can only fly the airplane if it has valid inputs from its sensors. In case it detects any issues with its subsystems or sensors, the autopilot disengages.
- The autopilot could disengage in case of heavy turbulence or if it doesn’t understand how the airplane is responding to its commands.
- The autopilot can only work when its associated systems have complete redundancy.
Just like any other system of an airplane; autopilot can also malfunction. Considering the crucial role of autopilot in terms of flight control, one may ask, is it safe?
Is the Autopilot Safe?
Autopilot systems are inherently safe in terms of their operation, and they are quick to disengage whenever they sense any error in their associated systems. As soon as autopilot disengages, it generates a warning for the pilot to take over controls.
Nevertheless, a disagreement between the situational awareness of the pilot or the autopilot system can be dangerous. That is pilots always must maintain complete alertness during a flight and must know when to take control of the airplane.
As the autopilot system is always aware of the airplane’s altitude and heading as well, it also can make corrections if the pilot gives any erroneous flight control command. In essence, the pilot and the autopilot system keep a constant check on each other.
Summary
- Automation of flight has been an area of continuous technological advancement for over a century now. Airplanes and pilots certified for ILS Cat IIIc operations can perform automated landings. However, most landings are performed manually around the globe owing to limitations of either the airplane, the pilot, or the ILS equipment.
- Automated landings are performed by autopilot systems of the aircraft. These autopilot systems reduce the workload of a pilot significantly by taking control of the flight when activated by the pilot.
- Autopilot systems have not only made air travel easier for the pilots, but it has also become safer. When you are landing in dense fog or low visibility conditions next time, you will know you have autopilot systems to thank for that.
Happy flying!
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