You forgot sun spots. ;)

I tried my Magellan GPS in flight once. I got weird results - it seemed to show speed and altitude correctly, but the location on the map never changed.

Please continue the discussion in the Travel & Technology forum. Thanks for your understanding.

Jouy31
TravelBuzz moderator

Nonsense. A device which only *receives* a signal is not a threat to any avionics system - it is receiving a signal which is already present. TVs, radios, GPS, etc., all fall into that category - although all airlines ban TVs, radios, etc.

Now a device which transmits, retransmits or amplifies a signal - that is something which *could* in very rare circumstances cause an electronic signal fault along wiring which is not properly insulated due to age, wear, chafing, etc.

If the device picks up an existing signal, it's benign. If it transmits a signal, then it's not - although the risk is still low.

Not true :)

See http://www.flyertalk.com/forum/showp...3&postcount=23

I have the F.O.M. reference written on the back of my GPS to tell the FA.

Then why are AM/FM radios prohibited, since they only receive??

My understanding is that even a device that "only receives" actually does transmit a little bit, too. I agree that the threat is certainly very, very close to nil - and thousands of flights with operating GPS systems suggest that the risk doesn't exist - but the "no until yes" approach to safety is one that the airlines/FAA have always used.

To wit: Why is WiFi prohibited until the airline installs a WiFi system on their plane?

I've never heard of a passive receiving device transmitting any measurable amount of radio waves. I don't know why radios and TVs are banned - it never made sense to me.

In any event, you can go to a radio hobbyist store and buy a small VHF receiver (not a transceiver) for a "do it yourself Channel 9" setup - just don't extend the antenna :)

14 CFR section 91.21
 

For those who think that someone is lying when they say that there is an FAA rule prohibiting the use of GPS units by passengers while in flight, I can assure you that they are not lying.

Title 14 of the Code of Federal Regulations section 91.21, Portable electronic devices, states that no one may operate and no one may allow the operation of personal electronic devices (and a GPS unit is a PED). Now, there are some exceptions and airlines that allow the use of various PEDs are following the rules when they allow their use.

Here's the whole section:

§ 91.21 Portable electronic devices.

(a) Except as provided in paragraph (b) of this section, no person may operate, nor may any operator or pilot in command of an aircraft allow the operation of, any portable electronic device on any of the following U.S.-registered civil aircraft:

(1) Aircraft operated by a holder of an air carrier operating certificate or an operating certificate; or

(2) Any other aircraft while it is operated under IFR.

(b) Paragraph (a) of this section does not apply to—

(1) Portable voice recorders;

(2) Hearing aids;

(3) Heart pacemakers;

(4) Electric shavers; or

(5) Any other portable electronic device that the operator of the aircraft has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used.

(c) In the case of an aircraft operated by a holder of an air carrier operating certificate or an operating certificate, the determination required by paragraph (b)(5) of this section shall be made by that operator of the aircraft on which the particular device is to be used. In the case of other aircraft, the determination may be made by the pilot in command or other operator of the aircraft.

Not only do many receivers generate RF, but computers, handheld games, and anything else with clock oscillator in them do. If it has a crystal timebase in its circuitry, it's probably radiating.

But unless and until the source of mysterious avionics anomalies is proved, I think to err on the side of caution is prudent.

American and Alaska specifically prohibit them.

I have the Garmin eTrex and I'll turn it on if I'm in a window seat to see where we are. I also had an older Garmin that I would use to check the speed and altitude since it didn't have a map.

I turned my eTrex Vista C on once, looked at the speed, altitude, location, noticed a couple of landmarks below then turned it off. More of a novelty than anything else.

The humor came a few weeks later when, after a drive out to the mountains, I hadn't reset the trip. Upon reviewing the trip info, I got a laugh out of seeing 550 or so MPH as my max speed!

I use my Garmin all the time. It's fun to track the flight against actual landmarks, as well as to watch speed and altitude changes as they occur. I can't wait to try it on a trans-oceanic flight -- it will be my own AirShow.

I only once had a problem because of it. On a UA flight, an FA told me I'd have to turn it off. I told him that UA's list of permitted electronics specifically includes GPSs. He went to see the captain who told him that I could use it if I could "prove" it was certified as an FCC Class B device. It doesn't say so on the unit itself (or my eyes were to bad to see it) so I turned it off. When I got home, I checked and, of course, it is FCC Class B certified. I now carry a copy of that page of the manual with me.

This, btw, was the same captain who refused to turn on Channel 9. On disembarking, I told him that I didn't appreciate either his refusal to allow me to use a UA-approved device or the absence of Channel 9. This was, evidently, a "labor action" flight.

Wow. Two "very"s. Must be all right, then.

No, it doesn't. Hundreds of thousands of uneventful Boeing 747-100 trips preceded the ill-fated flight of TWA 500. All that can be said about PEDs is that none has triggered a catastrophe yet.