Commentary: Do not fear flying on the Boeing 737 MAX 8
Despite crashes, fly-by-wire software has made aircraft safer by reducing pilot error, says the Financial Times' John Gapper.
LONDON: When two aircraft of a new model crash shortly after take-off within months of each other, killing all the passengers on board, and airline regulators in several countries respond by grounding or blocking the jet, it takes a brave or calmly logical person to climb on board.
But that is how passengers should treat the Boeing 737 MAX 8.
You could wait until next month, when the software fix to the aircraft’s occasional tendency to override the pilots’ instructions and push the nose down after taking off has been fully rolled out.
But the era of “fly-by-wire” being an experimental technology is in the past and the data is clear — the more that aircraft rely on onboard computers to assist pilots, the safer they have generally become.
TWO CRASHES
The fatal crash of an Ethiopian Airlines aircraft leaving Addis Ababa on Sunday (Mar 10), with the loss of 157 lives, follows a downing of a Lion Air flight off Indonesia in October, with 189 lives lost.
Pilots of the Lion Air flight apparently failed to stop the aircraft repeatedly overriding them when a sensor wrongly signalled to the flight control system that it was in danger of stalling.
It is unclear yet what happened to the Ethiopian Airlines flight but its unsteady rate of climb suggests a similarity to the Lion Air accident.
That was enough for China to ground the 96 new model Boeing 737s in service in the country, followed by similar decisions in Australia, Singapore and the UK. The US Federal Aviation Authority has become unusually isolated in declaring the aircraft airworthy.
FLYING DANGEROUS?
Grounding a model of aircraft even temporarily is rare — the last time this occurred was six years ago when Boeing 787s were stopped from flying for several months while it developed a fix for onboard batteries.
This is a full-blown crisis for Boeing in its rivalry with Airbus in commercial aerospace; single aisle 737s and A320s are the low-cost workhorses for many airlines.
But Boeing and US regulators are right — to the extent that the aircraft is flawed, the 737 MAX 8 can be fixed with new software, better sensors and some pilot training.
There is no need to turn off computers and return to humans taking full charge of the controls. Software has proved its value since the 1988 launch of the A320, the first “fourth-generation” fly-by-wire aircraft.
TECHNOLOGY HAS MADE FLYING SAFER
It is a familiar fact, but worth repeating, that flying is far less dangerous than it was decades ago — the 11 fatal accidents per million flights in 1960 fell to around 0.1 in 2017, with only six fatal crashes and 19 deaths.
The number of accidental deaths increased last year to 523, partly due to the Lion Air crash, but safety keeps on advancing.
The main contributor to this advance is technology, especially fly-by-wire software that responds to the pilots’ touch on the controls by adjusting the thrust, flaps and other surfaces to produce the desired outcome.
This includes “flight envelope protection”, which means that if a pilot tries to turn the jet too sharply, or push up the nose and risk a catastrophic stall, the software can disobey in some modes.
As fly-by-wire aircraft have superseded earlier generations of autopilot, the number of crashes caused by pilot error (which is responsible for more than half of accidents) has fallen. Nearly half the commercial aircraft in service are now fourth-generation jets, which have reduced “loss of control in flight” crashes such as the Lion Air case by 75 per cent, according to Airbus.
DANGERS ON THE BORDER BETWEEN HUMAN AND COMPUTER CONTROL
Technology has its drawbacks — the spread of fly-by-wire and use of autopilot means that some of the biggest dangers lie on the border between human and computer control. Pilots usually switch on autopilot shortly after take-off and do not fly manually until landing (the FAA estimates that autopilot is used for 90 per cent of flying time), which limits their experience.
The best known recent case of pilots being unable to cope without technology was the Air France flight 447 crash of an Airbus 330 over the Atlantic in 2009.
Its autopilot disengaged in a storm because airspeed sensors were blocked and an inexperienced co-pilot put it into too steep a climb. While the control system warned loudly of the danger, it stalled and fell out of the sky.
The 737 MAX 8 may have suffered the opposite problem — the pilots were flying both jets manually but part of the flight software is designed to override the aircraft’s tendency to pitch its nose up when climbing and turning.
In the Lion Air case, a faulty sensor reading could have made the computers respond as if it was breaching its flight envelope, although it was not.
FLY MANUALLY
The 737 MAX 8 crashes will turn out to have been avoidable if the fly-by-wire software contributed to losses of control. But Boeing need not redesign its aircraft entirely, and curbing the involvement of computers in flight systems more generally makes little sense.
The moral is that pilots should be sufficiently trained and practised to fly manually if required.
Given the choice of flying on an aircraft with pilots who are wholly in charge of the trip, or one on which software is able to countermand them if it senses an error, I would pick the latter.
The 737 MAX 8 accidents, tragic though they are, do not alter that.
Source: Financial Times/sl
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