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Wednesday, June 12, 2013

Below 10,000 feet...

I had a lengthy Internet dialog recently with an American Airlines captain about prohibitions on "personal electronic devices" (PEDs) on board. He believes that prohibitions ought to remain in place; I believe that some of them should be lifted. He knows a lot more about flying than I do, and I know a lot more about electronics than he does. I've been building radios since the mid-1960s, and he has been flying almost that long. I didn't convince him of my position, and he didn't convince me of his. Fortunately the FAA has begun a formal inquiry. Perhaps they will sort out the conflicting opinions. The very step of opening the inquiry, however, implies that all of today's prohibitions are no longer necessary.

Before I list which devices should remain banned and which should be permitted in my opinion, I'll make four points. One, rules are rules; for the time being, all passengers must comply with all the rules as they exist at any point in time. Non-compliance not only is criminal, but it could jeopardize me as your fellow passenger -- and you don't have that right. Two, until now it has been each airline, not the FAA, who decided which PEDs are permitted and which are not. Airlines have sometimes differed in their policies. Three, prohibitions of PEDs date to the mid-1960s when transistor FM radios were found to interfere with VOR and ILS, which are important radio-navigation systems. Banning radios was fully justified at the time. Four, the question must not be phrased in terms of "can interference to an avionics system ever happen?" The answer to that question will always be Yes, just like the answer to many other troublesome, far-fetched scenarios in aviation will always be Yes, they could happen -- but they don't. Some scenarios are so improbable that there is no sense in worrying about them, high stakes notwithstanding.

On to the details:

  • Radio transmitters. Except as stated below, all radio transmitters should remain banned unconditionally. No CB radios or family band walkie-talkies, ever!
  • Scanners. These should remain banned. I was amazed that Delta allowed use of scanners into the 1980s. Many scanners are among the "noisiest" of radio devices. Some scanners are not, but there's no practical way for an airline employee to distinguish the sheep from the goats.
  • FM receivers. They are still problematic until all future passenger aircraft are certificated to be resistant to interference from PEDs -- something the FAA should insist upon. By the way, many standalone MP3 players have FM receivers embedded. I don't worry about those because of how they're designed, but I do worry about a transistor FM radio from the 1960s even in today's aircraft.
  • Wired headphones. They are ok to use above a certain altitude, but passengers must be alert for crew instructions when on or near the ground. Many airlines use 10,000 feet as the cutoff. There's no point in arguing about the specific altitude because now that 98% of turboprops have gone away, passengers spend very little time below 10,000 feet.
  • Wireless headphones. As for wired headphones. Wireless headphones use Bluetooth, which is the most innocuous radio technology imaginable.
  • Laptops. Sorry but these must remain stowed below 10,000 feet. They tend to require lowering tray tables, and nobody wants a heavy laptop bouncing around a passenger cabin. Note that my concerns about laptops are not derived from radio interference.
  • Laptop cordless mice. They are still a concern. Some use Bluetooth, but others don't and those are potentially problematic until new aircraft are designed. This is another sheep-and-goats question. The good news is, cordless mice are seldom used by the passengers these days, so no significant inconvenience is imposed by the prohibition. Note that cordless keyboards for tablets and smartphones are of no concern because all of them use Bluetooth.
  • Tablets and e-book readers. They are ok at any altitude, so long as they don't have embedded cellular radios (see next point). Tablets and e-book readers pose no safety issues of any kind other than a possible lithium fire, and we've already accepted that possibility because it is not altitude-dependent. I'd rather be hit by a flying Kindle than by some of the massive hardback books that I see passengers bringing on board.
  • Cellphones, including smartphones and Blackberries. 1G phones were a huge concern with respect to interference, but they're long gone. 2G phones won't be around much longer. I know of no radio safety issue from 3G/4G/LTE cellphones at any altitude or anywhere on the ground. Skeptics of allowing cellphones have looked hard for a smoking gun but never found one. However, I do not approve of on-board use of cellphones -- except after touchdown -- for many reasons. There are few things more irritating than having the passenger next to you talk loudly into a cellphone; a plane is not like a train in which you can move to the "quiet car". Engineers at AT&T, Verizon Wireless, and Sprint have concerns about the impact of airborne cellphones on their networks, which were never meant to accommodate airborne phones. As a practical matter, the antennas in the base stations of AT&T etc. are designed to radiate horizontally not vertically, and their base stations are deployed along highways. Good luck with getting a cellphone signal when flying over most of Utah! Data usage, you ask? Your connections will, in general, be spotty and slow. In short, I think airborne cellphone usage for voice or data is an unworkable scenario and I hope that the FCC agrees.
  • WiFi connections. Airlines already sell WiFi above 10,000 feet. As a practical matter, they shut off the WiFi below 10,000 feet to discourage use of laptops -- a policy that makes sense to me.