Handheld GPS on Airliner?

[skyeye]

I was recently on a long-haul B747-400 from Heathrow to Cape Town, and wanted to try out my new duty-free Garmin GPSIII Pilot.

Being a law-abiding citizen, before switching on in flight (the unit picked up half a skyful of satelites if held close to the window, while on the apron), I enquired if such a device was permitted. After some delay (and some confused interest from the stewards: "A GP-what?...") the message came back from the flightdeck that GPSs are not on the list of approved electronic devices! Being totally passive devices, with perhaps a certain amount of RF generated by internal power streams, I can only imagine that the real reason for its omission from the list is because they are not yet very wide-spread "consumer" devices. Anyone have any thoughts?

The crew were quite friendly though, and I got a visit to the flightdeck, which was really the original intention!

(edited for typo)

[This message has been edited by skyeye (edited 29 June 2001).]

[englishal]

I've seen 'passive' GPS's re-radiate through their antenna on the original frequency and knock out all other GPS's in a 2 mile radius ! I was on a seismic survey ship at the time and it took us about 2 days to figure out that a 'passive' GPS was transmitting. Turned out to be a fault with the antenna connection, so this is probably why they are not permitted electronic items. Mind you, on one flight to Singapore, my mobile phone managed to turn itself on in my bag, stayed on for 8 hrs of the flight, and didn't do anything. Since then I've taken to removing the battery !

[skyeye]

Englishal
Knocking out other GPSs in the area wouldn't have been an issue in this case - it was an older model B747, with only inertial navigation installed - no GPS whatsoever. But an interesting possibility. I'm not electronically gifted, but I guess transmitter and receiver circuitry are similar enough for a receiver to become a transmitter in perculiar circumstances?


[This message has been edited by skyeye (edited 29 June 2001).]

[Manflex55]

Skyeye,

I use my handheld GPS-COM very often in the corporate jets I fly, mostly for info purposes (no moving map in the a/c GPS unfortunately) & NEVER had any problem with the nav equipment or anything else. Besides, it's a great back-up if something goes wrong (radio or nav failure).

MF

[englishal]

It'll never be a problem in a million years, just like listening to a CD player on T/O or L/D has a one in a billion chance of bringing down an airliner......After all they take these A/C and blast them with every possible frequency to make sure that no spurious interference will cause any problems....just being (over)cautious if you ask me.

Incidentally, TV detector vans detect your TV by picking up energy re-radiated by your TV, which just goes to show, passive receiving devices can actually transmit!

[skyeye]

Well ok, but a TV is something of a special case - strong high-frequency magnetic fields and very powerful electron beams. Not quite a "transmitter", but more of a RF noise generator. Moot point actually, because the in-flight entertainment TV screens are often on during TO/LDG.

According to the FCC, this GPS is a Clas B digital device, and complies with Part 15 (whatever that means), but has the standard all-encompassing statement about "this unit generates, uses, and can radiate Radio frequency energy, and if not installed and used according to blah blah blah". So basically it shouldn't be a problem, but don't try it.

I'll stick to using it in my light single...
;-)
Skyeye

[Tarmach]

This argument I believe is ill-founded! Of course you can use a GPS on an aeroplane of any kind. Yes the GPS unit does emit EM radiation as any electric device does. However, as for the argument that this radiation knocks out certain systems in the aircraft is ill-founded. Lets face it, EM radiation including radiowaves are present everywhere in the environment. Pilots should be more worried about high energy cosmic rays that can change logic sequences and corrupt data than someone with a GPS unit or even a mobile phone on board.

[HugMonster]

There is still a lot of research going on into the effects of PED's (Portable Electronic Devices) of all kinds on aircraft systems of all types. There is considerabel circumstantial and anecdotal evidence that GPS's, mobile phones, even CD players can cause interference. They are currently searching for the hard evidence into the above.

There is, therefore, some doubt as to the effects of specific devices. I was always taught that, where flight safety is concerned, "if there is any doubt, then there is no doubt". In the meantime, I am sure people would prefer to be safe than sorry, and therefore would not use PED's without permission.

Mobile phones may not legally be used at all on board an aircraft unless specifically designed for the purpose since all base stations within sight perk up and try to provide a service. Therefore it is possible for one mobile phone to seize up an entire network.

Next, it is conceivable that hijackers or suicide bombers could use information from a handheld GPS to decide exactly where to take action. Therefore some airlines are rather sensitive about this sort of thing.

And finally, it is illegal to use any PED aboard any aircraft if the airline tell you you may not use them. If you disobey a lawful instruction, you are liable for any and all consequences of your action.

[twistedenginestarter]

A neat feature of United is you can listen to the R/T. Must be popular otherwise they wouldn't do it.

In the same vein it would be nice if you could choose the captains HSI display on your in-seat tv.

[radeng]

FCC Part 15 is the US standard for non -intentional radiations from electronic equipment of all kinds, as well as intentional radiators used in certain services, such wireless local area networks, cordless phones etc. The levels specified there are such that a device meeting the requirements could radiate a signal on a frequency that caused interference - most probably, but not necessarily only, with DME or TCAS receivers.

There are corresponding European requirements. (These are 'EN' or 'European Norme': they are produced by ETSI, the European Telecommunications Standards Institute for comms type gear, and CENELEC - European electrotechnical standards committee for other gear) Incidentally, unless the device is CE marked, its use in the UK is illegal under the Electromagnetic Comaptability Regulations 1992, although in practice, that bit of the regulations is honoured more in the breach!

Most radio receivers are of the type known as 'superheterodynes' in which the incoming frequency is converted to another one for signal processing. This conversion uses an oscillator, which is the fundamental part of a transmitter, and there specific limits as to how much radiation is allowed and on what frequencies. Domestic equipment has quite lax limits, one reason being to allow TV detection! The EU Automotive Directive has got some real stupidities in that it allows considerably less radiation from a car radio than a fixed one, so that when driving down the street, you don't upset somebodies radio reception, but you can do it permanently. There are no special protection limits for any band used by aircraft, which considering that FM broadcast radios can radiate a lot of energy into the VOR channels, seems crazy to me.

It has been claimed that radiation from receivers was used by U boats to home on convoys in WW2, although I have my doubts on that one.

Aircraft aren't that good on immunity - there's been some discussion on the Passengers and SLF list abt this. There is, for example, a limitation on the use of Electronic News Gathering (ENG) equipment at and near airports because not all airliners can be guaranteed to have the necessary immunity to the field strengths that ENG can cause. Tornado fighters are renowned for their EMC difficulties, too. I'm inclined to think that there's a lot of 'say No because we don't know' involved though, when you consider that radar at LHR and the field strength that puts out at aircraft - when they're landing, too. There was a statement at a European meeting (from the CAA, if I remember) that they expect it will 2020 before immunity to 20volts/metre will be established in aircraft. Maritime safety radios require immunity to 10volts/ metre; cordless telephones and the like 3v/m and TV sets 1.8v/m. Portable radios have no requirements at all.

To put things in perspective, a typical mobile phone at full power will produce a field strength of about 0.4 volts/metre at 10 metres distance.

[pilotwolf]

When tried to use my GPS315A on board a A360 to LAX counldn't even get it to lock on to a signal whilst in flight.

Assume that the a/c skin was acting a screen to the gps signal....

[englishal]

"This argument I believe is ill-founded! Of course you can use a GPS on an aeroplane of any kind. "

--unless you're on a passenger aircraft as a passenger, and the law says you can't......then you can't !

[Final 3 Greens]

Skyeye

I am sure that the guys were just following their SOPs.

I've had mixed responses with my GPS92 - Aer Lingus thought it was great and I was asked to sit up front and show the Capt how it worked.

He said he was going to buy one after seeing it in operation - "be stupid not to have one in the flight bag at that price."

KLMuk allowed it in the cruise (the cabin crew were fascinated.)

KLM (mainline) and Airtours not at all.

The bottom line is that sticking to SOPs is what it is all about for these guys. (And the SOPs are oriented around safety )

[Zeke]

As a sideline along the lines of equipment interference, there has been some recent talk wrt high energy particles from the sun being able to interfer with satellite and aircraft systems by changing the items in memory as they pass through the vehicle.

It has been said that electric potential of the stored bits in memory may get "dislodged" (change polarity) with the passage of a high energy particle leading to computer faulures.

Now is your aircraft certified for flight into known solar flare conditions ?

[Intruder]

There are at least 2 issues here: Will a properly-operating handheld GPS interfere with the operation of the aircraft; and is such operation permitted by the operator?

I fly GPS-equipped 747-400s for a living, and also have a GPS-III+ that I use [mostly] for sailing. I've brought the GPS with me on operating flights and have found:

(1) the GPS won't lock on to any satellites in the cockpit (probably due to electrically heated windows and other interference);

(2) the GPS WILL lock on and track near any of the upper-deck windows;

(3) I have not seen any evidence of interference with aircraft systems.

As a pilot, I would NOT at all appreciate a passenger turning on an "unapproved" device without informing/asking the Crew first. OTOH, I would be inclined to allow such operation once I knew where to look if the unlikely interference bug bit...

[TR4A]

Southwest Airlines allows the use of GPS in flight only. Not during taxi. takeoff nad landing. All electronic items have to be stow.