LOOK MUM, NO HANDS
... but can a computer be trusted to fly an aeroplane?
Four-time Walkley Award winning political commentator and Churchill Fellow, has returned to the fray over concern that the integrity of news dissemination is continually being threatened by a partisan media.
Many airline operators prefer the Airbus fly-by-wire system in preference to risking pilot error. Aeroplane manufacturers deliver only what the buyer wants, the problem is that most buyers have never flown an aeroplane, certainly not under IFR (instrument flight rules) conditions, and pilots aren’t to be trusted to fly such expensive machines.
The misinformation coming from commentators is close to irresponsible. Let’s get one thing clear, only the pilot is in complete command of the aircraft and no one else.
Flight controllers will designate a standard instrument departure (SID) or the pilot will comply with any other departure instructions. He will be given a flight level on his heading that will allow for safe separation and will receive approach and landing instructions at his destination, and that’s it. Decisions of safety are the pilot’s alone.
Under stress of weather the pilot may ask for a different flight level, if it is refused and the pilot believes his aircraft is at risk, he has every right to tell the controller he is taking whatever heading and flight level he believes is safe, it’s then up to the controller to sort out the relevant separations.
Over a period of forty years contending with the severest of storms and with 7,300 hours' flight-time in just about everything that flies, except for a hot air balloon, I have learnt to trust instruments rather than trust myself.
The two most important instruments to have serviceable in a convective storm system are the airspeed indicator and the attitude indicator, you can afford to lose just about every other instrument and still remain alive.
Okay, the attitude indicator (most IFR rated aircraft will have two) is a simple gyro and rarely malfunctions, it tells you the attitude of the aircraft.
But the airspeed indicator, of which there will also be two, both rely on Pitot tubes which measure dynamic ram airflow pressure and are housed outside the aircraft and are subject to everything from icing to ant nest and spider infestation.
Some catastrophic accidents have occurred when Pitot tube protective covers have been left on.
The Pitot tube will give the pilot an “indicated” airspeed relative to the conditions and not a speed over the ground as is the case with a GPS. For instance, if you are flying into an 80kn headwind, your GPS SOG will show you are going 80kn slower than your airspeed indicator.
The fly-by-wire Airbus A320-200 is designed to rely on a computer corrected, four-axis auto pilot that will anticipate and correct aircraft movements faster and smoother that any human can.
A serious problem arises when Pitot tubes feed the computers an incorrect air speed. All hell breaks loose because computers are not rational and can only respond to what they are told. The pilot can turn the autopilot off and switch to manual control but he will be no better off. No other instrument will make sense to him.
If the pilot of QZ8501 decided to climb to a higher altitude to avoid a storm (and it is reported he did) he would lose speed and airflow over the control surfaces. If the Pitot tubes, due to icing or for any other reason, were already falsely indicating a low indicated airspeed, the pilot would be told in no uncertain terms over a loud speaker that his airplane was about to stall.
It was reported the airplane was climbing at 190kn, well and truly below stall speed for this aircraft.
Now every pilot is trained to react to a stall warning by automatically lowering the nose to increase speed, let’s say the pilot does so. The aircraft is now close to VNE (never exceed speed of around 0.85 mach at 35,000 ft) yet the computers and the pilot are still being told it is close to stall speed and they’d better correct it.
So now the pilot has a nose down attitude and is increasing speed past VNE. Add extreme turbulence and the next severe up-draught to that equation and the wings and vertical stabiliser get ripped straight off.
The pilot now realises he and everyone else on board are about to die while the computers are still happily responding to exactly what they have been told.
No doubt pilot error will again be the finding. He had asked if he could climb to a higher altitude due to stress of weather, he did not advise the air traffic controller that he was going to climb, in which case it would have been the controller’s separation problem. He instead waited some minutes for a clearance to flight level 38.
Okay, the tops of these monsoonal storms can reach up to 60,000 feet, a height at which this airplane cannot be flown, the air’s thinness means margins for safe flight are too narrow, and he has no way to know the height of the convectional storm anyway.
Now some pilots will disagree, but I’ve been tossed around and thrown upside down like a rag doll in too many monsoonal storms and my rules are now simple; go left, go right or go back.
Never try to go to under or you’ll likely finish up in someone’s lounge room and never try to go over because you may never reach the top and by then the black/green mass will have closed in below and behind you.
Airline operators want their pilots to merely monitor computers but when it becomes necessary to switch the autopilot off in an emergency it’s a terrifying experience, suddenly you feel the unusual pressures on the control surfaces and if a Pitot tube full of ice crystals is giving you incorrect readings it’s goodnight Irene.
If you’re about to die from a great height you really need a pilot and not a computer managing your rapid descent... at least a pilot can turn to you with a grimace and say, “Shit, sorry mate”.