Thursday, 3 January 2013

What is the dog there for?

Hello and happy new year to everyone!

After an all-too-short break we are back at school with a bump, racing to fit in the remaining phase one material before exams start on 21st January. One of the subject we are working on is autoflight.

I'm sure it is no surprise to anyone reading this that passenger jets are flown, most of the time, by autopilots and not by the pilots pulling on control columns and shoving on pedals like you see in the movies. In fact, many jets do not even have control columns, but that's another story.

What you may not know is just how far this automation has gone. Our instructors enjoy winding us up about being button-pushers or sys-admins rather than real pilots, or about how little work we will actually do, or how boring the job is. This is partly because most of our instructors are frustrated ex-flight engineers who were made redundant by increasing automation on the flight deck.

The flight engineers are not the only ones to be consigned to history, the navigators and the second officers have gone too, all replaced by computers and sophisticated control systems.

Just the two pilots remain — but for how long? Are single pilot or even pilot-less cockpits the future?  To answer this we need to look at what the automatics can and cannot do.

Computers everywhere

It is computers that have made the high degree of automation we see today possible. Large planes are stuffed full of them. They have been responsible for a huge increase in safety, reliability and efficiency of operation.

There are computers running laser gyroscope-based inertial reference systems and computers that analyse the data from the probes and sensors outside the aircraft and still more computers communicating with radio navigations systems. These all feed into computers that work out the statistically most likely position of the aircraft and feed this information into many other sources.

A horizontal situation indicator (navigation display)
from an Airbus. Note the weather radar display (large
blobs) and the purple line showing the planned route
that the aircraft will take - with no help from you!
The main ones are the flight management computers that provide navigation both laterally and vertically, flight director computers that indicate to the pilot the most efficient way to fly this course, and of course autopilot and autothrottle computers that mean they do not have to.

When a control is actually moved, it may no longer be connected to anything physical. Instead it produces an electrical signal to, you guessed it, a computer that decides exactly how far and fast the control should move, and prevents the pilot or autopilot doing any manoeuvre that could overstress the aircraft. Other computers prevent stalling via stick shakers and pushers and even simulate the 'feel' of old fashioned mechanical controls.

Information on the aircraft's attitude, speed, altitude, vertical speed, heading and so on is displayed on a computerised readout called a Attitude Director Indicator, and another computer-controlled display called a Horizontal Situation Indicator gives navigation information, weather radar and so on (see picture). Between the pilots, a further pair of displays (fed by various computers) give information on engine performance and aircraft systems together with any warnings.

Still more computers contribute to safety by providing ground proximity warnings and traffic avoidance, fault warning systems, voice and data recorders and devices to allow the aircraft's position, height and identity to be constantly sent to other aircraft and controllers via radar and data link systems (you can see this information live on websites such as

The avionics bay of a Boeing 737 - where many of its computers live
Some of the most advanced computers are control and monitor the engines. With dozens of sensors they will spot impending problems before they become serious, and both the airline and the engine manufacturer will know about it before the plane even lands.

These are just the main computer systems that I can recall right now, there are more. Braking computers. Weather radar computers. Pressurisation controllers. I could go on.

All of the vital ones will be at least duplicated. In total there will typically be several hundred separate computers whirring away on a current passenger jet. This is not perhaps the most elegant way to organise things, and party explains why a new Airbus A380 will set you back around $403 millon. I'm sure that as the designs evolve the systems will become more and more integrated.

What they can do

Put simply, the computers can do almost all of the flying. They can do it more safely, comfortably and accurately than the human pilots 99% of the time, and with less fuel used.

A few pieces of key data and the route to fly (usually simply a company route number) are entered into the flight management computers before takeoff, and once airbourne the systems will be switched on and will often fly the entire journey. With some help, many can even land the plane.

When there is a change of plan, air traffic control will contact the pilots with a new flight level or waypoint for example, and the pilots have to check and tap this information into the flight management computer. The information is often sent electronically via a data link, so it's not hard to imagine closing the loop and depriving the pilots of this small task too.

What they can't do

Most landings are still flown manually despite autoland often being available, and this is a skillful and workload-intensive task. The computers do help out enormously by guiding the pilots on the correct glide slope and approach path and warning of various errors or deviations but ultimately the pilots usually land the aeroplane.

Currently, I don't know of any autopilot in use that can take off, so this still remains an important job for the pilots. The take-off is not a difficult manoeuvre, but if things go wrong a quick decision of whether to abort or continue is essential to avoid either running out of tarmac or trying to launch an unflyable plane. Even so, auto take-off cannot be far away.

So as it stands, the pilots take-off and land, and the rest of time the computers fly. The flight crew programs and monitors the systems and handles the communications — and of course they are in command not the machines — but it is the computers actually flying the plane.

So what are the two rather well paid guys in the smart uniforms really doing to earn their keep? The answer lies in that 0.1% of the time when things are not going to plan. The unexpected. The unpredicted. The unimaginable. This is where pilots must step in and do the one thing that computers cannot —  make critical judgements in difficult or unforeseen situations.

Some of these judgements are fairly routine, for example the best way to cross a line of storms or a decision about where or when to divert based on what you expect the weather (and other traffic) to do. Others are completely unique, such as a medical emergency or lunatic passenger or (rarely) major equipment failure.

As our textbook puts it; "The ability of the pilot to evaluate evidence and come to conclusions will, in future, be the only reason for keeping him on the flight deck."

In other words, computers are stupid. They cannot, yet, operate outside of the conditions that the programmer intended and they cannot come up with create solutions to problems.

What about the dog?

And the dog? What is the dog there for? Well, so the joke goes, we will soon be moving to a new flight crew; one pilot and a dog.

The pilot is there to feed the dog, and the dog is there to bite the pilot if he touches anything.

Let's hope not, at least not for a good while yet!


  1. Smashing read, mate. Keep them coming!

  2. From what I understand, the dog would have been very useful on that AF flight from Rio that disappeared in the south Atlantic a couple of years ago.

    But I suspect what will keep you in the cockpit for longer than functionally necessary are legal issues - nobody's yet worked out how to prosecute (or even more important, sue) a computer!

    And then something like this comes along: Ah, smartphones - awesome tech.


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