21.03.2019
Disasters waiting to happen?
Yassamine Mather examines the facts behind two tragic plane crashes and the loss of hundreds of lives
When it comes to the two airline crashes that cost the lives of hundreds of passengers in recent weeks, we should have known that we could rely on the US president and his staff to make the most ill-informed comments. Donald Trump himself tweeted: “Airplanes are becoming far too complex to fly. Often old and simpler is far better”, before claiming that the increasing automation of planes results in “complexity” that “creates danger … I don’t know about you, but I don’t want Albert Einstein to be my pilot.”
In response to negative reactions, Fox TV’s Katie Pavlich defended Trump: “To give president Trump some credit, everyone’s like, ‘Oh, what does he know about planes?’ The guy’s owned planes his entire life ... and when you own a private plane you know about the way it functions.”1
Clearly that is not the case. As far as the Einstein comment is concerned, nothing could be further from the truth. We are in the era of auto-pilot and, far from needing expertise in physics, mathematics or general relativity theory, the pilot’s role is considerably reduced in most passenger aircraft. Of course, this does not mean that a plane carrying humans can fly on its own or be controlled remotely, as is the case with drones. The complexity is in the design of new aircraft and the software designed to control it.
It is now assumed (although not established) that those two recent air crashes - that of an Indonesian aircraft in October 2018 and an Ethiopian plane earlier this month (both involving a Boeing 737 Max 8) are related. The October crash killed all 189 people on Lion Air flight 610, while all 157 people aboard Ethiopian Airlines flight 302 died. Final reports are not due for several months and at this stage Boeing’s own investigation is concentrating on improving the plane’s control software. The company assumes that providing a better set of pilot displays (showing the state of various parts of the aircraft, as well as altitude, pressure, etc) and improving “manual and crew training” will resolve the issue.
The 737 Max 8 is a relatively new aircraft, first flown in January 2018 - Boeing claimed it was a more efficient version of the older 737, with better aerodynamics. According to the Wall Street Journal (March 13), the company’s software ‘upgrade’ could have been delayed by the 35-day US government shutdown in late 2018-early 2019.
By concentrating on the software, Boeing hopes to avoid any investigation into the design of the aircraft. Some experts have questioned the repositioning of the engines in this model - they are moved slightly forward and raised to avoid sucking in debris during taxiing. This had the effect of moving the plane’s centre of gravity - a well-known issue in aircraft design. If an aircraft’s nose is too low it can cause major problems, but if it is too high the plane will stall. Boeing was aware of the problem and designed a computer software called Maneuvering Characteristics Augmentation System, which is supposed to automatically prevent stalling. The software is connected to sensors on the plane’s fuselage and if they detect that the nose is too high the software automatically forces the nose down. In the case of the Indonesian aircraft, investigators came to the conclusion that the pilots were unable to determine two crucial pieces of information: the plane’s speed and altitude. This led to a situation where the plane was completely out of control, oscillating for around 10 minutes.
Passengers who had flown on the same plane just before the crash told investigators that the flight felt like “a roller-coaster ride”. In addition pilots have reported safety concerns about the Boeing 737 Max 8 - one called the flight manual “inadequate and almost criminally insufficient” months before the latest disaster.
In the case of the Ethiopian airline, the plane reached an altitude of 1,000 feet before losing around 400 feet, and then for about half a minute was apparently flying at that altitude of 500-600 feet, while its speed continued to increase, reaching 300 knots. This would have inevitably led to disaster, so the pilots reacted by forcing the plane to climb sharply at this fast speed. This is the last thing we know - the aircraft was flying very fast and climbing steeply.
Why they had not been able to climb during that previous 30-second period is a mystery. But then the plane did climb - “nicely”, according to experts. It seems that, whatever had happened, the pilots eventually figured it out, so what then went wrong?
As I have said, passenger planes are becoming more and more automated. In 2017 Boeing claimed it was developing a totally automated plane that will not need a pilot. Apparently “Autopilot technology already does most of the work once a plane is aloft, and has no trouble landing an airliner even in rough weather and limited visibility.”2
This is not quite true. There is the notorious example of a passenger plane on autopilot, where the captain and first officer were so engrossed in a game of chess that they overflew their destination by a few hundred miles! Autopilot failed to detect the destination entered by humans. On a number of occasions recorded by aviation authorities worldwide, pilots have missed their destination because they fell asleep.
During the flight it is possible for pilots to take a rest. In November 2018, The Daily Telegraph headlined an article: “‘UK pilots fall asleep in the flight deck every day’: the lingering problem of cockpit fatigue”.3 There are numerous similar examples.
How does autopilot work? The system relies on a large number of transducers/sensors all over the aircraft, collecting precise information relating to speed, altitude and turbulence. The data is fed into a computer equipped with software capable of adjusting height and speed accordingly. In theory (I emphasise the phrase), it should perform the tasks of a human pilot. A route has to be entered into the computer, giving it a start and end position and allowing it to calculate exactly how to get to the destination. Throughout that route there are a series of points that the computer will note, relating to speed and altitude.
The autopilot is not capable of steering the airplane on the ground and, in any case, busy airports will make such a task impossible in the foreseeable future. So the pilot will be in control during take-off and in most cases then starts autopilot, which takes over for almost all the rest of the flight. In newer automated systems autopilot can land the plane - this has already happened on a number of occasions.
Different countries follow their own regulations, but in most countries, including the United States, a minimum of two crew members must observe the displays in the cockpit, showing data from the sensors and computers, at all times. In addition to information regarding motors, speed and altitude, these displays relate to cabin temperature and air pressure, the state of the doors, etc. Of course, there is the danger of misunderstanding or reacting in error to data presented by the automated system - that will inevitably occur from time to time in human-computer interaction. The airline instructors often tell pilots: ‘Let the computer do it, because it can do a better job than you.’ The assumption is that a pilot is constantly watching data provided by the autopilot system, as well as the system’s response to this data. In some ways anyone using a cruise control system in a car would understand what is involved. You might be able to keep a safe distance from the car in front, but the driver still needs to be fully aware of where the car is going.
In summary, contrary to Trump’s claims, you do not need an Albert Einstein to fly a passenger plane, but you do need better software programmers and engineers. You need airlines that take responsibility for the lives of millions of passengers and do not take risks for the sake of profits.
The 20% fall in the value of Boeing’s shares last week should be the least of their problems. Unless they can explain what has gone wrong with the 737 Max 8 their reputation as a global aircraft manufacturer will be severely damaged. But the real question is, why is such a central and potentially dangerous service run entirely on the basis of profit?