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Using your GPSr on an airplane


Poindexter
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Just got back from a week in Florida (away from all the snow which was just about all gone when we got back!) and used my GPS for the first time in flight. Really cool to see where you are and enable you to pick out features on the ground to orient yourself. You must be by a window though as you can see from this photo that the signals will not penetrate other than through the windows. This was shortly after takeoff, almost at cruising altitude. Heading down from Maryland, can you tell which side of the plane I'm on?

 

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Just got back from a trip last nite myself ... plotted the flight from Paris to San Francisco on a polar route. GPSr told me when to look out the window to see points of interest like Iceland, Greenland, and the Canadian NW Territories.

 

Anything to keep one's self amused during a seemingless endless 11.5 hour flight icon_smile.gif

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You are correct. Of course, you can also see that I have the GPS wedged between my leg and the right side of the plane. I was suprised to see that it only requires a speed of 180mph to take off. This was a small plane though, a 717 I think. Two seats on the left, three on the right.

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i did the same thing on a trip to Florida last year -- i was very entertained watching our speed on the plane and then seeing the route when i got home.

 

I just flew to DC (on ACA a division of United) a few weeks ago and during the the flight attendants little speech they said that a GPS cannot be used during flight. icon_frown.gif

 

i asked my sister about it (she's a pilot) and she doesn't know why they won't allow it anymore ...guess it's all new

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I used my GPS hooked up to my laptop on a trip to Florida. I was able to pull up Microsoft MapPoint and see a map of where we were . . and how fast we were going. Pretty cool.

 

Then last month, flying to Phoenix I clicked on the Cities database and pulled up nearest cities and found I was about a mile and a half from my home town. It would have been cooler if the clouds weren't too bad to see the ground, though.

 

Bret

 

"The kingdom of heaven is like treasure hidden in a field.

When a man found it, he hid it again." Mt. 13:44

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quote:
Originally posted by Poindexter:

You are correct. Of course, you can also see that I have the GPS wedged between my leg and the right side of the plane. I was surprised to see that it only requires a speed of 180mph to take off. This was a small plane though, a 717 I think. Two seats on the left, three on the right.


A consumer grade GPS (along with any other radio, which is all a GPSr is) should be OFF during takeoff and landings on a commercial flight. Every radio transmits a small signal (I'm not going into the technical reason why here) even if it's just a receiver. Sometimes even something that normally doesn't emit a strong signal can malfunction and transmit much stronger signals. Could be something like a crack in the case, or a poor solder joint inside. If you have a radar detector in your car, you might have noticed it goes off sometimes when passing other cars with radar detectors. Same idea. Only difference, on a commercial plane, if your GPS happens to malfunction and interfere with the planes navigation during takeoff or landing, you could cause a disaster.

Some airlines will allow it once you are at cruising altitude, where even if there turns out to be a problem, there is time to safely deal with it. Some airlines such as Airtran ban all radios at all times, just to be safe. Others may not allow a GPS now because of the upsetting effect it might have on other passengers post 9/11. Always best to check with the flight crew when you are boarding. A stewardess will usually say "NO" even if the airline allows it, just because it's safer to answer no then to find out.

 

Tae-Kwon-Leap is not a path to a door, but a road leading forever towards the horizon.

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So Mopar what you're saying is that when the stewardess and the captain says to "please turn off ALL electronic devices until we say it is SAFE to do so" it is for everyone’s safety and one that would leave any electronic device on is:

 

(1) Not listening to very important safety rules.

 

(2) Doesn't think that it would happen to them, until it's too late.

 

(3) Endangering 100's of other peoples lives not only their own.

 

(4) Not to high in the IQ department.

 

Thanks for pointing that out to me!

I will make sure I turn OFF ALL electronic devices when told to do so.

 

The early bird gets the worm, but the 2nd mouse gets the cheese.

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Turn Off Your Radio!

quote:
In January 1993, on a flight from Denver, Colorado, to Newark, NJ, an aircraft lost all directional gyros (electromechanical devices that indicate orientation) at cruise altitude. The captain instructed the flight attendant to go through the cabin and tell all passengers to turn off their electronic devices. She reported back that about 25 passengers with portable radios had been listening to a Denver Broncos playoff game and that one passenger was also using a lap top computer. Within two minutes of the Captain's request to turn the radios off, the gyros had swung back to their correct heading. Later in the flight, several Bronco fans covertly resumed their use of the portable radios, and again the directional gyros began to malfunction. The radios were then confiscated and no further problems were experienced on the flight.


quote:
In the early 80's, a British Harrier Jump Jet landed for the very first time on a US aircraft carrier. On the flight deck, the carrier's yellow shirted deck crew stood ready to secure the jet and roll it to the hanger deck elevator. On the bridge, a dozen pairs of eyes watched intently as the Harrier made its signature vertical landing. But as the powerful vectored thrust turbofan engine brought the aircraft down in its measured descent to the flight deck, a terrible accident occurred: Electromagnetic interference radiating from the carrier's massive island of electronic equipment disrupted the Harrier's electronic controls, and triggered the pilot's emergency ejector seat. The pilot was propelled through the canopy of the jet with explosive force, killing him instantly. On the flight deck, emergency crews worked rapidly to control the now pilotless plane. But the damage was done. Electromagnetic Interference (EMI), defined by NATO as an electromagnetic disturbance which interrupts, obstructs, or otherwise degrades the effective performance of electronic or electrical equipment, had claimed another victim

 

Tae-Kwon-Leap is not a path to a door, but a road leading forever towards the horizon.

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quote:
Originally posted by Indiana Jeff:

As far as GPSr on a plane, I have heard that the transmission frequency of the GPSr was not one that was even used for aviation purposes....


 

The frequency your receiver listens on is irrelevant. Chances are that the internal signals it's generating are on entirely different frequencies. There are complicated technical reasons why this is so, but your best bet is to just listen to the flight crew when they tell you to turn off your portable electronic devices.

 

Consider Mopar's quote above: is it really likely that there were critical navigation signals on the same frequency as a Broncos game? Probably not. But the radios caused interference nonetheless.

 

warm.gif

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quote:
Originally posted by Indiana Jeff:

How can the emergency seat be activated? I always thought it was a mechanical trigger, not electronic, for that very reason.

As far as GPSr on a plane, I have heard that the transmission frequency of the GPSr was not one that was even used for aviation purposes....


The trigger it self may be manual, but in most modern ejection seat designs, after that a computer takes over. Ejection seats are very complicated, with thousands of separate pieces, all which must be timed to work together with millisecond precision. In the case of a harrier, the computer first triggers an explosive charge that shatters the canopy before ejecting the seat.

 

Even though a GPS receiver by itself may not normally generate a signal on a frequency that causes any problems, it can in some cases combine with a non-interfering signal from another device to create a signal that does.

That was probably the cause of the problem with the commercial flight I cited above. No one portable radio caused a problem, but the net effect of several of them could have been deadly if it occurred at low altitude in busy airspace.

 

Tae-Kwon-Leap is not a path to a door, but a road leading forever towards the horizon.

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quote:
Originally posted by Mopar:

Translation: Whatever the pilot says, goes.


This is why I ask the pilot upon boarding whether I may use my handheld GPS unit in flight. So far the responses I've gotten have almost no correlation to the respective airline policy.

 

Jamie

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I am 100% in favor of following flight crew instructions regarding electronic devices. As much fun as it is to use a GPS in flight, the possibility of interference does exist (try operating two GPS's side by side sometime).

 

HOWEVER:

 

quote:
Originally posted by Mopar:

http://www.glenair.com/html/emi.htm

quote:
In January 1993, on a flight from Denver, Colorado, to Newark, NJ, an aircraft lost all directional gyros (electromechanical devices that indicate orientation) at cruise altitude. The captain instructed the flight attendant to go through the cabin and tell all passengers to turn off their electronic devices. She reported back that about 25 passengers with portable radios had been listening to a Denver Broncos playoff game and that one passenger was also using a lap top computer. Within two minutes of the Captain's request to turn the radios off, the gyros had swung back to their correct heading. Later in the flight, several Bronco fans covertly resumed their use of the portable radios, and again the directional gyros began to malfunction. The radios were then confiscated and no further problems were experienced on the flight.



 

This is utter BS, or at the very least an incredible coincidence. Radios don't make gyroscopes swing to the wrong headings, any more than they can make toilets flush or toasters pop up. A gyro is a mechanical device. Either the reporter had it completely wrong, and was talking about a GPS or VOR receiver rather than a DG, or the story itself is apocryphal.

 

As a pilot, I have found that operating my consumer GPS in the cabin of some small planes DOES sometimes have a noticeable effect on the installed Garmin GNS-series GPS units. YMMV.

 

--

Scott Johnson (ScottJ)

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quote:
Originally posted by ScottJ:

This is utter BS, or at the very least an incredible coincidence. Radios don't make gyroscopes swing to the wrong headings, any more than they can make toilets flush or toasters pop up. A gyro is a mechanical device. Either the reporter had it completely wrong, and was talking about a GPS or VOR receiver rather than a DG, or the story itself is apocryphal.

 

As a pilot, I have found that operating my consumer GPS in the cabin of some small planes DOES sometimes have a noticeable effect on the installed Garmin GNS-series GPS units. YMMV.

 

--

Scott Johnson (ScottJ)


I just tried to verify the story, and since every single reference to this seems the be word for word the same, including a claim that it was "Originally published in 'Air Line Pilot'", Maybe it is urban legend or reported wrong. While looking though, I DID turn up the NASA report mentioned, and a Subcommittee on Aviation hearing on Portable Electronic Devices: Do they really pose a safey hazard on aircraft which documents lots of cases where personal electronics interfered with autopilots and navigation systems.

Bottom line.... Everything off on takeoff and landing, and check with the pilot while cruising. Easy enough.

 

Tae-Kwon-Leap is not a path to a door, but a road leading forever towards the horizon.

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quote:
Originally posted by ScottJ:

I am 100% in favor of following flight crew instructions regarding electronic devices. As much fun as it is to use a GPS in flight, the possibility of interference does exist (try operating two GPS's side by side sometime).

 

HOWEVER:

 

quote:
Originally posted by Mopar:

http://www.glenair.com/html/emi.htm

quote:
In January 1993, on a flight from Denver, Colorado, to Newark, NJ, an aircraft lost all directional gyros (electromechanical devices that indicate orientation) at cruise altitude. The captain instructed the flight attendant to go through the cabin and tell all passengers to turn off their electronic devices. She reported back that about 25 passengers with portable radios had been listening to a Denver Broncos playoff game and that one passenger was also using a lap top computer. Within two minutes of the Captain's request to turn the radios off, the gyros had swung back to their correct heading. Later in the flight, several Bronco fans covertly resumed their use of the portable radios, and again the directional gyros began to malfunction. The radios were then confiscated and no further problems were experienced on the flight.



 

This is utter BS, or at the very least an incredible coincidence. Radios don't make gyroscopes swing to the wrong headings, any more than they can make toilets flush or toasters pop up. A gyro is a mechanical device. Either the reporter had it completely wrong, and was talking about a GPS or VOR receiver rather than a DG, or the story itself is apocryphal.

 

As a pilot, I have found that operating my consumer GPS in the cabin of some small planes DOES sometimes have a noticeable effect on the installed Garmin GNS-series GPS units. YMMV.

 

--

Scott Johnson (ScottJ)


 

OK, it is a case of things getting a bit twisted to make the story more interesting. Here is the TRUE story:

quote:
In September of 1990, a plane travelling from Boston to Youngstown/Warren, OH was advised it was off course and was issued a new heading. The plane’s navigational instruments showed it to be on course. After checking the cabin for portable electronic devices, the lead flight attendant informed the captain that 23 passengers were using AM/FM cassette players and one passenger was using a personal computer. The passengers were asked to turn off the devices and the flight proceeded without further incident

 

Tae-Kwon-Leap is not a path to a door, but a road leading forever towards the horizon.

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I used my GPS V on a Southwest flight between Columbus and Sea-Tac. After refreshing the almanac at each stopover (Phoenix on the way there and Vegas on the way back), the GPS V worked like a champ. I had satellite lock on at least 6 birds and less than 20' of accuracy for most of the trip.

 

On the way to Phoenix, the flight attendant stopped at my seat and asked "where does your GPS say we are?". He then went forward a few seats and passed the word on to a curious fellow passenger. As I was getting my carry-on, the woman across the isle asked if I "played that scavenger hunt game?".

 

By watching the display, I was able to snap a few pics of the Grand Canyon from the plane and it was interesting that on each of the four planes, we flew at pretty much the same airspeed and altitude for the majority of the trip.

 

So, props to Southwest for being one of the few airlines that specifically allow you to use your GPS in flight. Yet another reason that I will continue to choose them whenever possible!

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Recently flew down to Florida on United. Before I left, I checked their website for info on whether a GPS would be allowed in flight. They had a couple categories listing electronic devices. One category only allowed the items to be used while at the gate. The other category allowed them to be used at the gate, or during cruise (not at takeoff or landing.) The GPS-r was listed in the latter category. I printed that list and took it with me on the plane. But I had no trouble with flight attendants or passengers. Had it on for several hundred miles. My Rino120 was able to get lock on several sats. It does make a really interesting track log to look at once home.

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quote:
Originally posted by Roadster:

I hope at least you had them off on takeoff and landing?


 

Umm, yeah, thanks for asking.

 

Here is the track of my travels. I messed up on saving the track from PHX to SEA, but other than that I was able to capture the whole trip. Who would have thought that we'd fly over Omaha!

 

Seattle-VancouverFlight.jpg

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quote:
Originally posted by ScottJ:

 

[snip]

 

This is utter BS, or at the very least an incredible coincidence. Radios don't make gyroscopes swing to the wrong headings, any more than they can make toilets flush or toasters pop up. A gyro is a mechanical device. Either the reporter had it completely wrong, and was talking about a GPS or VOR receiver rather than a DG, or the story itself is apocryphal.

 


 

Actually, that is not quite correct. Certainly, the vacuum driven attitude indicator or DC driven turn coordinator in most general aviation aircraft is not going to be effected by EMI or even EMR. But, in a modern, high-end glass cockpit, the attitude and directional instrumentation is not directly viewed.

 

Like an HSI that is slaved to a magnetic direction finder off in the wing, flight director displays can be (and are) driven by modules mounted off at the center of gravity in the plane. It is the electronic coupling (sometimes inductive) between sensors and display that can be effected by RF and EM interference.

 

Interestingly (to me at least), the sensors themselves no longer have to be spinning gyroscopic devices. Crossbow has had one 'no gyro' gyro FAA certified (it borrows on the anti skid/slip technology developed for cars), and other companies have submitted products.

 

As for toilet flushing, here is a true story. A dark shirt causes the toilet at my office to flush spontaneously, and a white shirt causes flushes to get missed. Dead batteries cause continuous flushing. It isn't the good 'ol valve, but the electronic sensor - designed and built by idiots, that is to blame. If I could get it to flush using my GPS (or even my handheld VHF transceiver), I could at least have some fun (at someone else's expense).

 

As it is, I just have to resort to the low tech solution of draping white tissue over the sensor when I am wearing dark clothing...

 

-jjf

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quote:
Originally posted by BusBoy:

Here is the track of my travels.


 

Here are the track log and height profile of my flight from Greensboro NC to Chicago IL last week. This is the second time I've flown United and used a GPSr, with no complaints from the crew.

 

Unfortunately, I had to keep my eTrex Legend plastered to the window to maintain a signal. icon_smile.gif

 

Total Mileage: 643.82 miles

Moving Time: 1 hr 50 min

Max Speed: 486 mph

Moving Average: 350 mph

Overall Average:333 mph

 

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....someone that knows nothing about GPS and asks what you are doing and you say "trying to get a good signal so they (satellites) can track the plane."

 

Couldn't you imagine the look on that persons face before you can tell them the whole story? icon_eek.gif

 

The early bird gets the worm, but the 2nd mouse gets the cheese.

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... from The Sydney Morning Herald:

 

The truth about your laptop computer and landing safely

By David Higgins and Joel Gibson

September 15, 2003

 

Next time you're on a flight and the plane suddenly begins to climb or pitch to the left, don't panic. It's probably just the kid next to you conquering level 16 on his computer game.

 

Pilots have become accustomed to unexpected problems caused by passengers using mobile phones or other portable electronic devices.

 

Over the past decade there have been more than 100 incidents in Australia of navigation system failures, autopilot malfunctions, interference with radio transmissions, incorrect readings from flight management computers and false alerts from engine warning systems - all due to portable devices.

 

In one case last year, the ground proximity warning system in a 34-seater plane suddenly went berserk even though the plane - which was just 22 kilometres south-west of Sydney - had levelled off at 5000 feet.

 

The pilot noticed a mobile phone interference signal in his headphones, according to an incident report lodged with the Australian Transport Safety Bureau. "The aircraft continued to its destination without further incident," the log entry says.

 

On another occasion in 1996, a Boeing 767 pitched and dropped 120 metres before pilots recovered control. A passenger using an electronic dictionary was asked to turn it off, and the plane's systems returned to normal.

 

On more than one occasion, laptop computers have been blamed for changing an aircraft's internal cabin pressure.

 

Pilots routinely ask for portable devices to be switched off during take-off and landing. because they are too busy to deal with problems with interference. But, once in the air, when passengers are allowed to switch devices on, pilots have had to contend with a range of bewildering malfunctions.

 

The incidents, logged in an Australian Transport Safety Bureau database, have been collated for the first time and detailed in the latest edition of Flight Safety Australia, published by the Civil Aviation Safety Authority.

 

Perhaps most worrying of all, the devices often cause autopilot malfunctions, which have resulted in planes climbing, oscillating, or disengaging from the autopilot system altogether.

 

CASA wants to ban the use of mobile phones on all flights and prohibit the use of laptop computers, video cameras and electronic games during take-offs and landings.

 

CASA spokesman Peter Gibson said the level of interference was manageable but any increase would require more serious consideration. "None of these [incidents] led to anything life-threatening . . . but we have this issue constantly under review," he said. "The thing we're relying on at the moment is the common sense of passengers not to use mobiles, transmitters and other devices when they're told not to, and the vigilance of the cabin crew."

 

Laurie Cox, a spokesman for the Australian Federation of Air Pilots, said more research was needed into the effect of electronic devices.

 

"You've got to ask, do you want to get there, or do you want to use your laptop?"

 

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