GPS in an airplane

[OpalCat]

If you'll look at the link (Airlines which APPROVE/DISPROVE GPS use in Flight ), you'll see that most DO allow it. This includes Continental, Delat, JetBlue, N, SW & United. Flight crew can over rule this though.

Most of the airlines that do are not American-based, though. There are more US airlines on the "NO" list.

 

[nmm01]

I've run other gps's on airplanes before (where allowed) and had decent results.
The key is to get a fix while on the ground, preferably stopped, and keep it on as long as possible. The slower you go the faster you get a fix (try it in the car).
If you turn it off, it difficult (if not impossible) to get a fix again.

Also, as others have mentioned, the southern side of the plane works best.

 

[Adlerson]

It also helps to be on the side of the plane facing south or west.

Wrong. The 24 to 32 GPS satellites are spread equally around earth, so that at least 6 satellites are visible at any one point almost everywhere on earth. These are not your normal TV network satellites, so they're not concentrated to the south or west of most continental US positions. They will be south of you, north of you, west of you, and east of you.
It helps to be on the side of the plane with a most direct LOS (Line of Sight) to as many satellites as possible at any given time, but that varies with where you are.

I read somewhere that the GPS in the Droid resolves position based on input from a data (3G or WiFi) source, it's not a full-blown, independent GPS receiver. That could certainly be wrong, but that's what I recall reading.

Also incorrect. Specifically, the location unit in the Droid is an A-GPS, or Assisted GPS. What this means is that the GPS unit in the phone is a full blown, independent GPS unit, capable of calculating it's location by no other means but GPS satellites, if need be. However, it's not a /good/ GPS unit, the antenna for instance is small to say the least. So if the phone was to determine it's location using nothing but GPS it can take a long time, indeed as long as 20 minutes. So to help speed this up the phone also uses cell phone tower triangulation to secure a rough fix, then feeds this to the GPS unit, which can then fine tune this fix using the GPS signals.
This is why sometimes when you first open your map you'll see a rough estimate of where you are, though within seconds to a minute you'll exactly where you are.

Speed and altitude does not have any impact on being able to utilize GPS, it's the primary navigation system we use on the jet I fly. However, like others mentioned, the antenna(s) are on the outside of the fuselage, on the top, under a thin plastic cover. The reason you will have problems locking on when sitting in the cabin of an airliner is the relationship between the thickness of the hull of the aircraft and the strength (or rather, lack thereof) of the GPS signal; Each GPS satellite transmitter transmits it's signals with no more power than that of an average car headlight..
With that in mind hopefully it'll make more sense why you're having problems locking on any time you're inside a building, under a roof or in an airplane.

 

[ldimick]

You are not permitted to operate a portable GPS on an airline.

It's actually up to the discretion of the pilot I believe. And every time I ask I am told NO. They are afraid you are tracking them for nefarious purposes.

The rules may have changed since 9/11.

 

[rap4974]

You are not permitted to operate a portable GPS on an airline.

It's actually up to the discretion of the pilot I believe. And every time I ask I am told NO. They are afraid you are tracking them for nefarious purposes.

The rules may have changed since 9/11.

They will always tell you NO if you ask to use something. All they will do is ask you to shut it off if they have a problem, usually they don't unless you're below 10,000 ft.

 

[rap4974]

It also helps to be on the side of the plane facing south or west.

Wrong. The 24 to 32 GPS satellites are spread equally around earth, so that at least 6 satellites are visible at any one point almost everywhere on earth. These are not your normal TV network satellites, so they're not concentrated to the south or west of most continental US positions. They will be south of you, north of you, west of you, and east of you.
It helps to be on the side of the plane with a most direct LOS (Line of Sight) to as many satellites as possible at any given time, but that varies with where you are.

I read somewhere that the GPS in the Droid resolves position based on input from a data (3G or WiFi) source, it's not a full-blown, independent GPS receiver. That could certainly be wrong, but that's what I recall reading.

Also incorrect. Specifically, the location unit in the Droid is an A-GPS, or Assisted GPS. What this means is that the GPS unit in the phone is a full blown, independent GPS unit, capable of calculating it's location by no other means but GPS satellites, if need be. However, it's not a /good/ GPS unit, the antenna for instance is small to say the least. So if the phone was to determine it's location using nothing but GPS it can take a long time, indeed as long as 20 minutes. So to help speed this up the phone also uses cell phone tower triangulation to secure a rough fix, then feeds this to the GPS unit, which can then fine tune this fix using the GPS signals.
This is why sometimes when you first open your map you'll see a rough estimate of where you are, though within seconds to a minute you'll exactly where you are.

Speed and altitude does not have any impact on being able to utilize GPS, it's the primary navigation system we use on the jet I fly. However, like others mentioned, the antenna(s) are on the outside of the fuselage, on the top, under a thin plastic cover. The reason you will have problems locking on when sitting in the cabin of an airliner is the relationship between the thickness of the hull of the aircraft and the strength (or rather, lack thereof) of the GPS signal; Each GPS satellite transmitter transmits it's signals with no more power than that of an average car headlight..
With that in mind hopefully it'll make more sense why you're having problems locking on any time you're inside a building, under a roof or in an airplane.

Great info! Thanks for posting that

 

[ldimick]

600 MPH? What do you think the two folks up front are using to navigate at 600 MPH? What do you think supersonic fighter jets use to navigate at 1000 MPH? Yes, it's GPS. There are backup systems, but typically, the GPS is keeping the inertial nav updated, not the other way around.

Not GPS. GPS would be a backup system. They use GROUND based radio signals that are EXTREMELY directional.

 

[Tabs]

600 MPH? What do you think the two folks up front are using to navigate at 600 MPH? What do you think supersonic fighter jets use to navigate at 1000 MPH? Yes, it's GPS. There are backup systems, but typically, the GPS is keeping the inertial nav updated, not the other way around.

Not GPS. GPS would be a backup system. They use GROUND based radio signals that are EXTREMELY directional.

That's not true - with the right system specifications (WAAS, backups, etc), GPS is an approved primary nav source for most aircraft now. There's full blown instrument approaches called LPVs that use nothing but GPS guidance for both the lateral and vertical path. I've done one in a real aircraft equipped with the Garmin G1000 system.

On a large passenger jet, the main source feeding the computers is usually an inertial reference system (IRS) that uses laser gyros to detect the plane's motion in three dimensional space. The gyros can and do "drift" however and that's what the "GPS update" is for.

The ground based radio systems are called VORs (VHF Omindirectional Ranging) and on a modern "glass cockpit" jet, these are rarely used as a primary source at least while navigating in cruise. The computers & IRS/GPS can do everything VORs can but much easier and with a much higher degree of accuracy. VORs do however get used to update the IRS position, much like the GPS update - the systems will compare all three sources when available.

The radio system that is actually still used a ton is the ILS. (Instrument Landing System) This guides pilots down to a runway using two different precision radio signals, one for the lateral (called the localizer) and one for the vertical. (called the glideslope)

 

[ldimick]

600 MPH? What do you think the two folks up front are using to navigate at 600 MPH? What do you think supersonic fighter jets use to navigate at 1000 MPH? Yes, it's GPS. There are backup systems, but typically, the GPS is keeping the inertial nav updated, not the other way around.

Not GPS. GPS would be a backup system. They use GROUND based radio signals that are EXTREMELY directional.

That's not true - with the right system specifications (WAAS, backups, etc), GPS is an approved primary nav source for most aircraft now. There's full blown instrument approaches called LPVs that use nothing but GPS guidance for both the lateral and vertical path. I've done one in a real aircraft equipped with the Garmin G1000 system.

On a large passenger jet, the main source feeding the computers is usually an inertial reference system (IRS) that uses laser gyros to detect the plane's motion in three dimensional space. The gyros can and do "drift" however and that's what the "GPS update" is for.

The ground based radio systems are called VORs (VHF Omindirectional Ranging) and on a modern "glass cockpit" jet, these are rarely used as a primary source at least while navigating in cruise. The computers & IRS/GPS can do everything VORs can but much easier and with a much higher degree of accuracy. VORs do however get used to update the IRS position, much like the GPS update - the systems will compare all three sources when available.

The radio system that is actually still used a ton is the ILS. (Instrument Landing System) This guides pilots down to a runway using two different precision radio signals, one for the lateral (called the localizer) and one for the vertical. (called the glideslope)

I was under the understanding that VOR was THE primary system. I learned something new!

 

[hemi-droid]

I'll have in-seat power on my next trip. Does anyone think the gps receiver will be stronger on AC power vs. battery?