A rogue cosmic ray or solar radiation effect is now being considered as a possible cause for the mysterious but violent losses of control that injured 119 people on board a Qantas A330-300 on October 7 last year before it made a forced landing at Learmonth in WA .
But the second interim factual report by the Australian Transport Safety Bureau released this morning has not solved the riddle as to why the jet suddenly experienced two uncommanded dives while on its way from Singapore to Perth.
The key elements of the accident remain unchallenged. There was a fault in an Air Data Inertial Reference or ADIRU that overrode the normal error correction defences of the Airbus flight control system with spurious data.
The pilots were able to regain control of the jet each time it dived out of control, during which it experienced negative and positive G forces most people will only ever experience on a thrill ride at an amusement park.
Meticulous testing of the jet and its avionics components has failed to identify any fault in manufacturing or servicing which could have caused the errors.
The particular A330 involved in this incident experienced a similar but less serious ADIRU fault while in flight on September 12, 2006, but in a different unit and without causing any drama.
The jet was even flown for nearly 11 hours in May with all possible on board sources of electromagnetic interference switched on and working at up to 2.5 times their designed levels in an attempt to determine if computers or the in-flight entertainment system could affect the jet’s systems.
They didn’t. It also loitered for two hours close to the Harold E Holt naval communications base near Learmonth while that facility’s powerful radio transmitters were going full bore, and they had no effect on the jet either. (Scratch popular speculation about death rays, spy devices, secret weapons and so forth.)
The interim report explains why the QF72 incident bore no resemblance to the fatal crash or an Air France A330-200 operating AF447 on June 1, including no iced pitots or external air speed measuring issues, and ADIRUs of different design and manufacture being fitted to each jet.
On possible solar or cosmic radiation influences or what are technically referred to as single event effects or SEEs, the ATSB says they “have been suspected of generating some of the soft errors that occur in a wide range of different aircraft systems.”
“The investigation team is evaluating the relevance, if any, of SEEs to the ADIRU errors…”
The ATSB says changes to operational procedures in the use of ADIRUs in Airbus A330s and the four engined A340 version have significantly reduced the chance of another in-flight upset being caused by such a fault.
It will issue a final report by the middle of next year.
Sounds like the effects of a UFO.
Cosmic rays can flip bits in computer memory. They are rare but worth considering. Aircraft flight computers contain Error Checking and Correcting (ECC) memory, which can correct 1 and 2 bit failures without a problem and reports if it can’t correct itself. The incidence of cosmic rays at flight altitudes is perhaps one every 5 hours over 1GB of RAM. What is the likelihood of multiple cosmic rays just happening to hit the memory in just the right place to not crash the software and the ECC memory failing – and the redundant computer systems not picking it up? Pretty low I’d say. Even your laptop at flight altitude, when hit by a cosmic ray is very unlikely to be affected in any observable way.
The article in The Age today mentioning flight software being updated reflects a non-understanding of what’s going on. Updating the software when you think a cosmic ray has flipped a memory bit is pointless – that would be a hardware problem (as we software engineers like to claim).
In the power industry from the late 60’s to late eighties analogue controls using operational amplifiers like the LM301 and LM308. These systems were very sesnsitive to radio frequency (RF) VHF and UHF transmitters. On a number of occasions the operation of hand held walkie-talkies caused boiler turbine units to trip. With the introduction of microcontroller based digital systems the effect of such RF interference has been substantially reduced. The high speed digital systems are no where near as sensitive to radio interference as the old analogue stuff. With the introduction of wireless networks electronic engineers spend a lot more effort on rendering their designs insensitive to RF. My experience would back up the opinions of Ben Sandilands and David Green on this issue. RF interference is unlikely to be the problem.
As a software engineer I would put my money on the software being the problem or a physical sensor or actuator. Not the controls processors. We replace humans with computers, sensors and actuators, but then put humans in charge of these systems when they go wrong. The human should get a medal if they can recover from the malfunction. They usually only have seconds or tens of seconds to diagnose the problem, determine an appropriate course of action and then to carry out the action and monitor whether it is was the right thing to do.
In the late seventies the Victorian Power system came extemely close to collapse as a consequnce of power flow instability. The operators at Yallourn W Power station put the automatic voltage regulators on manual and saved the day. The SECV power system engineers conceded they had helped prevent catastrophe. As a consequence power system stabilisers were fitted to all large units and the problem was solved.
Operations at the Harold E Holt communications facility were never in the frame for this incident. HEH is primarily a VLF (very low frequency) transmitter built in the Cold War years to communicate with US Navy nuclear submarines patrolling the Indian Ocean. VLF has the ability to penetrate water so could be used for launch orders should the Soviets have started WW3. VLF is very old technology and if you visit the site you can see the beautiful timber framing that supports the VLF equipment in the transmitter room. I have been there a number of times in my work for the company that used to run the place for Defence. Apart from some of the new Defence HFMOD VHF gear recently installed there, I don’t think there is any ‘secret squirrel’ or any other ‘spooky’ stuff there. That’s at another place in WA.
From the little bit of information I have gleaned, perhaps solar and cosmic interference should be seriously looked at.
Have any Boeing aircraft had similar problems ? There seems to be quite a difference in how these two brands of planes operate. Airbus , I believe, fly higher which changes both the stalling speed and the maximum speed to more critical levels. I believe it uses a lot more fuel than Boeing. I also believe that the Airbus works on a lower voltage than Boeing. Perhaps someone with electrical experience can give some pros and cons for this. Finally, I know from experience that the business class seats on Boeing 777-300ER are far more comfortable than the Airbus A340-500