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Personal Electronics May Indeed Disrupt Avionics
mattrwilliams writes "There is a growing body of anecdotal evidence that points to personal electronics being a real issue on board planes. Dave Carson of Boeing, the co-chair of a federal advisory committee that investigated the problem of electronic interference from portable devices, says that PEDs radiate signals that can hit and disrupt highly sensitive electronic sensors hidden in the plane's passenger area, including those for an instrument landing system used in bad weather."
There is a growing body of anecdotal evidence
Need I say more?
If planes switched to fiber optics and got rid of copper wiring I'm sure that would reduce the likelihood of interference. I can hardly wait for the day people will be able to use their cell phones on those long haul flights.
"You'll get nothing, and you'll like it!"
A couple of coats of lead based paint will take care of that.
"A person is smart. People are dumb, panicky dangerous animals and you know it." - K
These planes can take direct lightning hits but the sensors cant handle a cell signal that's going to be there weather the phone is off or not?
does not compute
I was told by people on the internet that this cannot possibly happen, so this expert from an actual aircraft manufacturer must be wrong.
ILS receiver antennas aren't "hidden inside the passenger compartment".
They're "attached to the outside of the friggin airframe".
Any story that gets the details that wrong, that fast, receives no credence at all. And if airplanes are having this much trouble with my 2mw iPad, what the *hell* are they doing about getting hit by 2GW of lightning?
(And don't tell me "Faraday cage"; that protects the occupants, but not necessarily the things connected to antennas outside the cage.)
There is a growing body of anecdotal evidence
Need I say more?
Actually, yes. How about something regarding consequences? Say 100+ people in a fragile machine, surround by flammable liquids, moving at a high rate of speed and doing so with limited to no visibility outside the machine having a "mishap" because someone had to check twitter? There are some activities where an excess of caution is warranted, personally I believe that needing to use an ***instrument landing system because of bad weather*** is one such activity.
I had always been suspicious of the reality of small electronics and avionics interference, but now I have some first hand experience--I fly a small airplane (a Decathlon). Granted, it has much different RF characteristics than a large airliner. Like most airplanes, it is equipped with a transponder that encodes the airplane's altitude and transmits it when the air traffic control radar paints the airplane. Sometimes when my iPhone is turned on in the airplane, the altitude reported by my transponder varies wildly by several thousands of feet, and air traffic control tells me they are getting spurious signals. One day when this was happening, I thought ah heck and I turn off the phone, and the transponder settled down. I turned it back on, and the transponder started going wonky again. I've reproduced this on a few different days and most days with no issues with the phone turned on. I'd say it's 20% bad/80% good. I haven't figured out what conditions cause this to happen or not--could be poor equipment installation. Anyone else with actual experience of something like this happening?
As an engineer who designs and integrates RF systems every day, all day, I have two impressions. And as a systems engineer, I'll describe them in terms of the two elements of risk: probability and impact.
FTFA: "In other events described in the report, a clock spun backwards and a GPS in cabin read incorrectly while two laptops were being used nearby."
First: Crap like that ain't supposed to happen. An airplane designed and built to standards for commercial passenger service must meet standards for electromagnetic susceptibility, interference tolerance, workmanship, etc. It's not the passengers' fault that things like that happen. Nor is it the direct fault of the manufacturer of the electronics that passengers carry. If something is that mission critical, and the cost of failure is measured in human lives, then engineers, inspectors, regulators, and operations crew damn well better make sure the likelihood of failure is as close to zero as can be.
Second: I know damn well that grounding and shielding is one of the most difficult aspects of any high-frequency electronics system. It's difficult to design, grounding and shielding design rules aren't generally taught as part of undergraduate EE curriculum (much less Aeromechanical, CS, etc.), and the manufacturing techniques are prone to failure and not easy to inspect and test. Therefore, statistically, a passenger that travels one or two times a year is likely to board a plane with a design flaw or manufacturing/maintenance flaw at some point in their lifetime. This doesn't mean they're going to notice it, or even have any effect on the flight, much less cause an emergency by forgetting a powered-up iPhone in their carryon. But the likelihood of failure will never be zero unless the passenger obeys the rules and turns off their devices.
So, turn your shit off when so instructed.
And consumer electronics designers: please give the consumer a switch that allows them to turn their shit off... not standby, but OFF.
I can see the fnords!
Here we go again, every couple of years an article relating to avionics interference shows up in slashdot and I have to come out of my cave to save the world...
Here is something I wrote back in 2006 about this same issue.
Just because you are 'an engineer' who 'works with RF' doesn't mean you know tiddly about avionics. I actually work at an avionics lab and repair and test these devices and have actually measured RF interference of avionics systems, both on the ground and in the air. Its my job.
As a fellow engineer I could give you a 5 minute brief on how the ILS system works, another 15 to go through explaining all the board level receiver circuits, data busses and another 20 to go throught the navigation computer and autopilot at block diagram level - and afterwards you'd be rolling on the floor laughing to the very idea of a passenger ipod being able to interfere with 'the ILS system'... unfortunately my superiors are hunting me down to lock me back to my cave now.
For others see what I wrote about Ultracrepidarianism
www.tribalnetworks.org - helping tribal people around the world to own their own means of high-tech communications
Somewhere there is an engineer that argued quite vehemently that there is no way the air speed sensors on an Airbus A330 could possibly all fail
There is/was no engineer that argued this. Instead the argument was, "if this happens, what can we do to improve safety in that event?" That failure mode was thought of, I have absolutely no doubt. Engineers thought it was covered, they may have been wrong about that but I'll discuss that later.
leading the engines to stall in mid-flight
An aircraft stalling does not involve the engines, it involves airflow over the wings. Do you have any knowledge of the topic at all? Nothing I've read indicates there was an engine failure on that flight.
The aircraft crashed because when readings became invalid, the computer automatically disconnected the autopilot / autothrottle (as it should have). The pilots then made control inputs that were inappropriate for the situation. They were probably confused by the relative lack of data they had, and the multitude of warnings a complete air data failure causes. The pilots then held a nose up attitude through multiple stall warnings, eventually entering a period of extremely high sink rate. The aircraft had pitched up in excess of 35 degrees through this period, and the pilots held full nose up control inputs through almost all of it. It was the exact opposite of what they should have been doing. The pilots held the stall all the way into the ocean, impacting the water while still in a nose up attitude of more than 16 degrees.
I know people like to get up in arms whenever a crash is blamed on pilot error, but it's pretty clear in this case that the pilot's actions were inappropriate and their inability to recover from the stall despite ample opportunity will almost certainly be listed as the main cause of the accident. There were many contributing factors, but the data suggests that the aircraft would have flown just fine if given proper stall recovery inputs.
What could the engineers have done better? Indicate in a more useful way what was going on and which instruments were reliable. The pilots should have been able to tell at a glance what they should pay attention to and what they should ignore. The avionics display design may not have been good enough for them to do that. The stall warning may have deactivated inappropriately based on the invalid speed, because the computer thought the aircraft was traveling too slow for the angle of attack indicators to function correctly. This failure mode should not exist in my opinion. Either the angle of attack indicator should function at lower speeds, or an alternate stall indication should be used instead. Or just keep the warning on, since the aircraft is quite obviously not in landing configuration. From what I read, they were probably assaulted with a whole host of failure warnings that were confusing and may have contributed to a panic reaction.
Also, pilot training needs to be improved in some areas, especially involving loss of pitot static data. There is no reason an airplane of any type should crash because of a clogged pitot tube. This should be drilled into pilots starting with the most basic beginning flight training. I know from experience the topic is not covered at that level, besides a couple questions that may appear on the knowledge test. In fact, if I had not actually had a pitot tube get clogged during my training, I would have never encountered the situation at all.
There's some fairly good discussion about the events of the flight here.