Random thought of the day

If having your cell phone or other electronic device turned on could jeopardize the safety of an airplane then why allow electronic devices on the plane at all? Why couldn’t a group of suicide terrorists carry high powered electronic devices on airplanes and turn them on during critical portions of the flight and bring them down at will? Or even aim a directional beam at planes from the ground and bring them down?


One has to conclude that the prohibition against having your cell phone turned on is just more security theater.


Update: Some awesome stuff in the comments. I think I need to back down some on my claims above…

15 thoughts on “Random thought of the day

  1. They can’t tell. If you forget and leave your cell phone on in your pocket (where the flight attendant can’t see it), they won’t say anything to you and nothing will happen. I’ve done this a few times by accident.

  2. I believe at one time interference was an issue. The issue now is more of one of distraction… if you are playing a game, listening to music, etc, you can not hear them say there is a problem and give directions. Plus, they might have updated the safety procedures, so you should listen up! 🙂 Oh, I forget the airline, but at least one has gotten clearance to put all their flight manuals on iPads for use in flight.

  3. The ban on cell phones is an FCC rule and an FAA rule. A plane full of cell phones traveling 400 miles per hour playes heck with cell towers and they have a clear line of sight to all of them at once in a city.

  4. @MikiJ, If the distraction were a concern then they would let you turn them on as soon as the finished the safety briefing rather than require you wait until you get about 10,000 feet.

    @Alan, I can sort of understand the cell phone issue (sounds like a security vulnerability that needs to be mitigated) but that doesn’t explain why you are not allowed to use your Zune or iPod or even have your cell phone in “airplane mode”.

  5. Its mostly laziness, they adopted the rule out of an untested fear and now no one wants to be responsible for testing devices to see if there is really an issue. Bureaucrats.

  6. We could only wish it was “laziness”. I’m not in the EME (ElectroMagnetic Effects) group but I do work with them (think large company in the NW that would be on topic). Money to do the testing is probably the biggest factor but the competency and guts to actually make an explicit call of yeah or nay are in the mix also.

  7. Let me give you my perspective as someone who’s job is primarily airworthiness and deals with the FAA and their regulations on a regular basis.

    In our basic terminology, airworthiness means: A demonstrated capability to operate without significant hazard to aircrew, ground crew, passengers (where relevant) or to the general public over which such airborne systems are flown.

    We in the business are pretty darn sure that in general portable electronics don’t pose a significant hazard to aircraft but nobody has ever demostrated that in a rigorous engineering test. Secondarily, airworthiness is demonstrated on a configuration by configuration basis, so you would have to demostrate that on each and every device individually or show via analysis that new devices are substantially similar enough to qualify based on past approvals. Neither is a simple or easy process.

    Then the question becomes, who is going to conduct the testing necessary to approve these devices? The FAA doesn’t do that. They set requirements and review data in order to grant airworthiness approval but they won’t do the testing themselves.

    So you’ve got two choices, either the device manufacturers can do the testing or the airlines can do the testing. Device manufacturers are probably not going to go through that process. Apple just really doesn’t care if you’ve gotta wait till you hit FL10 to use that shiny IPAD.

    Now the airlines have gone through some very limited testing. American Airlines pilots can use IPADs as an electronic flight bag at low altitude if they follow a multitude of restrictions with regards to it’s operation and configuration. For people in the back, guess what, yet again the airlines don’t care if you’ve got to wait to FL10 to use your toys, so they’re not going to pay for testing for the general public at large.

    And without the engineering substantiation to back up the decision, I will be very surprised if the FAA ever authorizes the use of PEDs at low altitude. Nobody is going to take the personal legal responsibility for that decision with nothing to back it up.

    I would also add that in the course of assisting with EMC source/victim testing on a King Air 200 and a Cessna Citation Encore, I have seen with my own eyes, carry on electronics interfering with the communication and navigation systems. For the Citation, an FAA TSOed transponder went completely crazy from, as near as we could tell, the CPU clock from a laptop. Now those instances were due to some bad wire shielding and in general it’s not an issue but who here wants to bet that the 737 built in 1984 still has all it’s shielding at 100%?

  8. If I remember the Mythbusters episode correctly, they showed that SOME phones (mostly not used now) COULD cause SOME of the navigation systems to fail, IF there were no shielding. The reason for the complete ban is that creating a list of allowed and disallowed devices are is a pain, and causes a lot of arguing at the gates. The other issue is that jumbo jets are rather complex machines. While they should be shielded properly, sometimes maintenance and repair isn’t totally 100%.

    Basically, the chances of terrorists being able to board a plane and take it down by turning on a bunch of cell phones or something would most likely fail, because the plane is MOST LIKELY properly shielded, so a target approach isn’t going to work. However the chances that some plane could be taken down from such interference, if EVERYONE has such devices is much greater.

  9. To second aeronathan’s example in a non-aircraft setting: when I was dispatching for an EMS helicopter service any Nextel device in the room would create a distinct and easily audible interference on our phone and radio system as soon as it went active. I could tell someone would be getting a call or “direct connect” before the phone ever rang just from this signal. I often wondered what that would do on an aircraft.

    Oddly, only Nextel phones would do this. The multitude of computers and monitors installed in dispatch were fine. I guess that just shows that such interference would likely be based on the specific combination of “interference receiving” equipment and phone/PADD/etc. I doubt anyone at the FCC will ever be willing to take the chance that some catastrophic combination won’t occur, especially considering the fact that it won’t be just one single device, or even one single model of device, that will be in use on most flights, but a random mishmash of whatever the passengers on that leg of the flight happen to have. The randomness makes it even worse – will an Airbus computer tolerate 10 iPads but turn the plane upside down if an 11th one is turned on? Will it tolerate a dozen iPads or a dozen Kindles, but just one of each on at the same time would send it into an electronic seizure?

    It’s not a security issue, or even a probable issue, but there are so many random and unpredictable factors involved that I doubt anyone in control would be willing to risk it.

  10. @Jake: Nextel was known for interfering with 911 radio traffic in the 800mhz range. Something about the tower-to-tower freq they used.

    I say this ban stems from the old days, 20 years ago, when cell phones operated on different freqs and used a higher-power signal. That’s all changed, but one thing hasn’t: the phones the airlines have at your seat. They get a large chunk of money from those phones ($9/minute to call, used to be), and so they ban everything which might cut into that profit center.

  11. There is some evidence that PEDs have caused interference during some flights: http://asrs.arc.nasa.gov/docs/rpsts/ped.pdf Most entries are about consumer electronics failing and/or catching fire due to faults or incorrect passenger usage or cases of argumentative passengers not complying with instructions.

  12. From a different perspective, I fly F-16s. We have a nice big multi-kilowatt frequency agile radar on the jet, and I can use it to lock up other aircraft in flight. Even at close range. I’ve never seen or heard of my radar interfering with the target’s navigation systems in 20 years of flying. The radiated power of the radar is much greater than a cell phone, even when the phone is much closer to the receiving nav system. Just a bunch of FUD. The average person is afraid to fly, and is interested in any comfort that the jet is as safe as possible. Since no one can rule out the possibility, it remains a restriction. Just part of the security theater.

  13. …And at what frequencies does your radar operate, Trigger? (Don’t answer that!) –Probably not the same as a celphone or wi-fi-equipped PED. So its a whole other can of worms and I’m betting the .mil folks take steps to ensure their toys are not incapacitated by A) high-power sigs in known radar bands and any they suspect and B) medium=power signals anywhere in the spectrum. Commercial airplanes are built on a tighter budget and to a different end.

    The celphone-in-flight ban IS because your phone lights up too many cells at altitude, and skips from one to the other more quickly than the system is generally comfy with; you end up burning up more bandwidth than you would down on the ground and with a whole planeload of phones, it becomes a big mess. With planeload after planeload doing it, it becomes worse than that.

    No-PEDs-below-10K is mostly about things other than graunching that DC-3 low-rent commuter air electronics. It’s not even so much about ’em bursting into flames. It’s about your laptop/iPad/KindleNook escaping your clutches and coldcocking a grandmother from Duluth. What’s a commercial aircraft doing under 10K? Why, landing, taking off or (rarely) evading weather: all times when the plane may be changing speed, direction and attitude with great rapidity and force.

    Any one individual PED is no big deal 99.9999999% of the time. A planeload of them is a problem. A planeload of them raining down on the steward/ess and passengers is a lawsuit.

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