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10 Myths about GPS

Aug
25
2006

Not necessarily the top 10 myths, rather myths we’ve been hearing lately.

  1. The Government can use GPS to track my movement. While there are some GPS receivers which have the capability to broadcast your position, the vast majority of GPS devices can only receive information from satellites and cannot broadcast any information.
  2. GPS receivers don’t work well when it is cloudy. People often describe GPS receivers as needing a “clear view of the sky”, however the clear view simply replies to not having any obstructions to the view of the sky such as mountains, tall buildings, dense canopy, etc. A cloudy day will not prevent your GPS from working. As an example of this, airplanes can use GPS to navigate down to a runway in cloudy or foggy conditions.
  3. Garmin is the only manufacturer of GPS devices. Garmin is the largest producer of GPS devices, however they are not the only manufacturer. This myth also takes on a slightly sarcastic component too since there are lot of people who say you shouldn’t consider anything other than a Garmin. Garmin is #1 for a good reason, they make great GPS devices, however there are lots of other companies who make great GPS products too.
  4. You should only buy a GPS device if it has a SiRF Star III chipset inside. The SiRF Star III chipset does have fantastic reception, and could be something to consider when purchasing a GPS, however it doesn’t trump sliced bread. For many uses og GPS even a 12 channel GPS receiver will work just fine and perhaps save you a couple of bucks too.
  5. If you buy a GPS today it will have up to date maps with the new development by my house. Unfortunately, this is a myth. Updated and corrected maps often take years to reach consumer devices despite claims from the manufacturers that their maps are up to date. The maps they provide might be the most recent set they have purchased (since they don’t make the maps themselves), but don’t expect the maps to be 100% accurate with the physical world.
  6. A GPS will prevent me from getting lost. (Outdoor recreational use.) A GPS will not always prevent you from getting lost. GPS devices are good at telling you were you are. A map and compass is still essential to carry to ensure you can get from where the GPS says you are to where you want to go. A GPS can’t read your mind and don’t often tell you where you want to go. They rely on batteries for power and when your batteries die you will still need to navigate.
  7. A GPS will prevent me from entering prohibited airspace. (For general aviation pilots.) Temporary Flight Restrictions (TFRs) can pop up anywhere, at any time. Your GPS data is only as good as the last database update which for many people can be years old. Always check for the latest NOTAMs and mark critical areas on both your paper charts and (if your GPS device supports it) in your GPS.
  8. The GPS navigation system available from the factory in my car must be better than “aftermarket” GPS devices. I’ve found most of the factory installed navigations systems to be difficult to operate… they just are not as intuitive to use in most cases. They are significantly more expensive than an aftermarket portable navigation device (PND). While they are more difficult to steal, they are also much more difficult (and costly) to upgrade with new maps, POI databases, and features.
  9. Auto GPS navigation systems will pick the best route to your destination. You could have fooled me while driving up the East Coast of the US and the GPS wanted to send me over the George Washington Bridge during rush hour. But even aside from traffic there is always “local knowledge”. Ever have an argument with someone over the best way to get from one place to another? Don’t expect the GPS to settle that debate. While there are companies coming up with some very clever ways to learn this “local knowledge” the technology isn’t quite here yet.
  10. It is perfectly legal to use my GPS aboard a commercial flight. It might be okay, depending on several factors. Remember, at all times you must obey crew member instructions. On some airlines it is in their policies to not allow GPS receivers to be used while onboard the aircraft. On other airlines there might not be a policy against it, in which case it is up to the crew. If they tell you not to use it, you don’t use it, end of story. Additionally, some GPS devices carry transmitters of some sort such as the Rino series from Garmin as well as Bluetooth GPS receivers. Since transmitter devices are not allowed on commercial flight this will also ground those types of GPS receivers from being used. In the end it is rare for all of the stars to align properly to allow the use of GPS onboard a commercial aircraft and I imagine it will only become more difficult with today’s security threats.

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19 Responses


  1. 2. Planes does NOT use GPS to land their aircraft (they use ILS). They cannot rely on GPS because the US Army can turn on SA at any time. This is one of the future benefits of Galileo.

    Morten - August 29th, 2006
  2. Have you ever tried to use GPS on a commercial flight? I would say that you are wrong in that you CAN’T use a GPS on a flight, not due to regulation, but because you are inside a metal tube and can’t get reception. (at least I can’t)

    Brian Norton - August 29th, 2006
  3. Morten – Yes, planes can use GPS to land aircraft. I guess the definition breakdown is how you define “land”. Each type of approach (ILS, GPS, etc) has different “minimums” established for how low you can take the plane without being able to visually see the runway environment. But at runways which have approved GPS approaches you can use GPS to navigate just like you would use ILS to navigate.

    There are now even certain runways which have “WAAS Approaches” that allow you to use GPS to approach certain runways which don’t have other ground based navaids at the airport. These are relatively new, but growing.

    Brian – In most cases you are correct in that it is very difficult. For most 12 channel receivers (as an example) you would need to be in the window seat with the GPS pressed up against the window for awhile before acquiring a signal. That in itself is bound to arise some suspicion as to what you are doing. However more recent receivers with 20 channels can much more easily acquire a signal and can sometimes even be done from middle seats.

    GPS Review - August 29th, 2006
  4. Hi there!
    I used a SirfII (ST&XT) onboard a regular flight. It was hard but I managed to make it works… fixed to the window. I also use a SirfIII with any problem. First time was authorized… second time… only a test 😉
    Greatings from Spain!

    Mr.Well - August 31st, 2006
  5. I tested my laptop Microsoft Streets and Trips with the included GPS on an A320 a few months back. Stuck the receiver to the window, just like in the car and bingo! Cruising at 560 mph with a tailwind and just broke 600 on the descent. It was cool but unknown if it was “allowed”.

    Dave G - August 31st, 2006
  6. Just because the article says that airplanes CAN navigate down to a runway in the fog, doesn’t mean that it’s commonly done, or advisable.

    Sasha - September 12th, 2006
  7. Thanks for the comment, Sasha. Ultimately it depends on the plane, the conditions, and experience of the pilot. I know lots of pilots who use GPS approaches in the plane on a regular basis and there are an increasing amount of airports which have GPS approaches (WAAS augmented) that do not have ILS approaches.

    As for it not being “advisable”, it is an FAA approved procedure therefore if the equipment and pilot certifications are available it is a perfectly safe procedure.

    Regardless, the point of myth #2 wasn’t to say that all planes use GPS in every approach, rather that the atmospheric conditions (being cloudy) doesn’t impact the reliability of the GPS signal. Thus, using as an example that aircraft can (and sometimes do) use GPS as a means of navigation when visibility is low.

    GPS Review - September 12th, 2006
  8. As stated above, GPS receivers will work well in the commercial airplane cabin when antenna is placed close to a window.

    I know that Southwest Airlines (USA) lists GPS in their magazine on the *APPROVED* list of electronic devices.

    United Airlines (USA) does not list GPS as approved.

    So – it appears the “usage rules” are somewhat arbitrary.

    So it

    Chuckles - September 25th, 2006
  9. […] Quite a few people have been asking us questions or making statements that leads us to believe there are some misconceptions out there about how GPS devices calculate routes, and what part of the process is responsible when an obviously bad route is being suggested by your GPS. Perhaps this should be appended to our 10 GPS Myths post. Let’s dig into this a little bit and figure out where the map data provider, the GPS device, and the GPS software play a role in calculating routes. […]

  10. I always use my Garmin 3+ when I fly – if I hold it near the window it allways works.

    Fred - October 10th, 2006
  11. I used my laptop Microsoft Streets and Trips with the included GPS on two USAirways legs flying 70 passenger regional jets. I stuck the receiver to the window just like Dave G above. It worked great. The stewardess asked me what I was doing and I told her I was using GPS. She was very interested and asked me how fast we were going. I said 478 mph at 21,000 feet. She came back a few minutes later and said the Captain said that was correct!!!!! She was young (25-ish) and she was very into the technology. The next leg was different. The stewardess asked me what I was doing, I answered GPS and she was very upset and said turn it off. So I unhooked the GPS receiver and was only using the map feature. I wat GPSas going to track our route “manually.” The stewardess walked by 2 minutes later and rudely reminded to turn off that GPS. I said I had disabled the GPS and she stormed off. She came back 2 minutes later and said the pilot had asked me to turn the computer off entirely because they copuld not be sure that I had actually disabled the GPS. I was very PO’ed…

    johnson - December 19th, 2006
  12. That falls under the “federal regulations require that you comply with all crew-member instructions” category. If they want it turned off, you must turn it off.

    Tim - December 19th, 2006
  13. johnson said, I was very PO’ed…

    I don’t blame you. Ever since 9/11, and to some degree prior, such harmless activity has been construed to have an evil purpose. I’m a photographer and I am routinely hassled by police, guards, etc. when I take pictures IN PUBLIC and on public property. Alas, this trend will never reverse.

    Robert Ricketts - May 9th, 2007
  14. quoted:
    “Alas, this trend will never reverse.”
    it will only get worse.

    fernie - June 22nd, 2007
  15. Before 9/11 I always asked the flight crew before using my gps. After 9/11 I always ask the flight crew AND talk with my seat mates.
    GPS use seems to be arbitrary between the airlines, but the captain on the flight always rules. Discussing GPS use with the passangers puts their minds at ease and often generates discussion and interest.
    I’ve found that by putting the GPS unit in my shirt pocket and sitting by a window (either side of the window) has worked well 99% of the time.

    Bob Elston - September 20th, 2007
  16. Just purchased MS streets w/gps-500 receiver. Will this gps-500 pharos work with google plus on my new laptop?

    Jim Bowen - January 12th, 2008
  17. I just used GPS on a Southwest flight last night. The signal wasn’t great. I too have Microsoft Streets and Trips with GPS, and I too placed the receiver on the window and it worked some of the time. Other times I had a hard time getting a signal. 550 miles and hour at 40,000 feet. I Thought this was strange because I looked at the specs on a 737, the only thing southwest flies, and for a 737-700 (the version we were on) the max speed was .82 Mach. this is only 537 MPH. (I’m not an aerospace junky)It was intersting, and no one asked any questions. The onboard magazine from the airline listed GPS receivers as an approved device.
    The other intersting thing is that you can see what city you are over or what state you’re over at any given moment. I recommend bringing your device and the biggest battery you can (I ran out in my laptop), and if they say “no”, they say “No,” and you comply.

    Josh - January 13th, 2008
  18. Hi Josh – I don’t know the specs for a 737, but I suspect the max speed you saw was probably for “airspeed”. Your GPS is essentially measuring the “groundspeed”. If you had a 100 mph tailwind, and the 737’s airspeed was 537 mph, then your GPS would register a groundspeed of about 637 mph.

    Tim - January 13th, 2008
  19. I have been useing a garmin gps on airplane trips all over the world for 10 years and have just found out that it is not allowed on some airlines;

    james wolf - September 3rd, 2010



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