Now I wanna see Boeing do the same with the 787 Dreamliner and its Melbourne-cooked cutting-edge composite flight control surfaces.

I’m not suggesting anything that would replace existing systems, which have been shown to work extremely well compared with ‘manual’ systems, but a referee system for situations like these that happen once every decade or so.

Do we need an entirely separate and almost always redundant system to resolve conflict in control between humans and the computer? A simpler, cruder version of the altitude/attitude sensors, that can be an automatic umpire if flesh and chips disagree?

This just moves your risk to another area.

Aerospace code is probably the most reliable in the world, because the consequences of failure are so dire. Boeing and Airbus spend serious money and effort on making sure it’s as safe as possible; but even so mistakes get made. Aviation has had disasters caused by various sorts of systemic, procedural or engineering failures since the very beginning.

The idea of having redundancy both between actual deciding units and the software or systems implemented has been explored and found mostly to be unsatisfactory. Boeing did a very large study and found that having multiple independent implementations of a critical piece of software did not reduce the number of bugs; rather they found that each group tended to make bugs in the same complex areas of work.

To be serious though I approach every flight as my last. I buckle up and stay so unless in the loo. I listen to the flight instructions and check my exit. I assume it will crash and being of a fatalistic bent, it doesn’t bother me.

Some say I am safer in a plane than driving to the airport, but in the latter case I have some control over the management of disaster than I do in a plane.

And it does concern me that pilots have so little control over adverse computer events.

Then again I have had a taxi driver from the Urals smelling strongly of alcohol and with needle marks on his forearms drive me to Eagle Farm airport, and I survived that.

Jack Hackett

I wonder , further, if it has occurred to you that your honest assessment of the computer system with a mind of its own and the more recent adoption of fly by wire system, might be counterproductive to your role a fear of flying mentor.

It would seem that the manual overide through the computer was not compromised by the faulty ADC. Would the pilots have flown the aircraft manually to its landing in this event? Or were they able to isolate the fault and continue on autopilot? And in the manual flight mode would the faulty altitude information coming from the ADC have affected the pilot’s flight instrumentation requiring them to guess the aircraft’s altitude?

Normally, a driver does not make a violent maneuver, but to avoid hitting another car, if a passenger is not wearing a seat belt, the passenger can be thrown about the car, and possibly injured even if the other car is missed.

Consider going ten times that fast. When going 550 MPH, any change in the direction the plane is pointed — just as in your car — can cause a person to be thrown about if they are not wearing a seat belt.

People simply will not follow directions. It seems to make no difference how many times flight attendants tell people to wear a seat belt, even when there is no turbulence and even when the seat belt sign is not on. Some will not do it.

Some people simply will not wear their seat belts in a car, either. But if you do, on a plane, you will be fully protected in case there is either unexpected turbulence or an autopilot malfunction, as in this case.

It is simple: wear the seat belt and no harm will come to you.

As to the specific problem, it was the Air Data Computer, a device that processes air density information and translates it — in computer code — into altitude. And here is the potential problem with the newest airplanes: we NEVER had a problem with a malfunction of the ADC with airplanes like the 747, 757, 767 which are flown — not by computers alone — but simply use computers to supply information. In the old system, the ADC and the computers had limited authority over the plane. But the newer planes by Airbus and the 777 are “fly by wire” which means — maybe I’m saying this too strongly — but it means the computers have taken over. THEY run the plane, and for a human to intervene, he or she has to aim the intervention at the computer. What if the computer says, “fuck you” and keeps doing what you want it to stop doing. The earlier planes let the pilot really take control and disconnect the computer. With the newer planes, you only ask the computer if it wouldn’t mind doing what you want the plane to do.

That approach was shocking to some of us old guys. Back when Airbus first built the A—320, we older and more conservative pilots says, “Screw that; we don’t want the computer in charge; WE want US in charge – period.” At UAL, our chief pilot – who we respected for his engineering knowledge — went to Airbus, studied the plane and said it was fine; we had nothing to worry about.

OK. Maybe. But though it has taken fifteen or so years for us to have a tricky situation like this where the computer was totally in control and had a malfunction of one of its information systems (that told it it was at the wrong altitude and tried to change it) those of us who had reservations about “fly by wire” (meaning by computer; even when flying manually, you tell the computer what to do to point the plane, using a joystick – not a control wheel connected to the controls) are thinking “told you so”.

So, clearly, though this kind of thing is rare (once in fifteen years) it did happen. That’s good or bad depending upon your perspective. But the ADC was shipped to the manufacturer in the U.S. to let them figure out the problem and come up with a fix.

That’s the logic. The there is an emotional issue as well. Most people can accept that something like this could go wrong every few years. Others have such anxiety around rare events that it makes flying difficult or impossible.

I have tried to give a good understanding of how flight anxiety works in a video at http://www.youtube.com/watch?v=Zcx6ZsvKHSA&feature

On 1 August 2005, shortly after departing from Perth, Australia, bound for
Kuala Lumpur, Malaysia, a Boeing B777-200 passenger aircraft suffered a
flight upset while climbing through 38,000 feet. It began when the aircraft
spontaneously pitched sharply upward, reaching 41,000 feet and activating
stall warnings. After pilots regained control they returned to Perth.

The incident was triggered by a second accelerometer failure in the
aircraft’s air data inertial reference unit (ADIRU). This unit is designed
to be highly redundant and fault-tolerant but the first failed
accelerometer’s failure mode was not one that had been anticipated during
unit design and development. (It had been assumed that a failure would
always result in zero voltage output, but this failed device was producing a
high output value.) The twin failures exposed a latent software fault, which
resulted in the unit feeding incorrect aircraft acceleration data to other
flight control systems.

Boeing B777-200 aircraft first entered service in 1995 and this is the first
reported instance of the particular software fault, which was apparently
present in the unit’s original design, affecting operation of an aircraft.
The incident highlights the fact that software testing can never eliminate
all risk.

The Australian Transport Safety Bureau’s investigation report is at
http://www.atsb.gov.au/publications/investigation_reports/2005/AAIR/aair200503722.aspx

* they don’t have any access to the instrument data
* they don’t know what the plane is actually capable of handling (as distinct from what a plane typically does on an uneventful flight)
* a lot of people have a phobia of flying.
* journalists, when choose a grab to run after a flight incident, will naturally gravitate to the person who gives the most exciting story.

- a government in its pocket on the question of flight and airport rights (see eg the cosy duopoly on the Sydney-LA route). That in turn depends on them being a big employer of Australians, which outsourcing endangers in the long run.

- its reputation as the safest airline in the world. They fill a niche for those who are willing to pay more and put up with lousy service to reduce their fear of flight. This is far more valuable than any savings on maintenance costs.

Claims naval base signal caused Qantas nosedive…..
http://www.abc.net.au/news/stories/2008/10/16/2392534.htm

A Singapore Airlines PR bloke yesterday implied on ABC radio that QANTAS’s paying immediate compensation to “The Exmouth 69″ was a very good investment by QANTAS in attempting to recover from a(nother) nosedive for their reputation.

That the airbus took a nose dive seems to indicate two of the flight computers were wrong, not just one. Might be a wiring fault, but given Qantas’ recent problems (which it seem are all due to poor maintenance) I reckon it’s time they sat back down with their cost-cutting spreadsheet and started factoring in the real costs of these incidents vs the cost of a few extra ground crew and more down time. Clearly their sums are currently wrong.