Alternative GPS solutions

[flyingguy1984]

Hi all,

I'm currently flying a PA28 that isn't GPS equipped. I'd quite like to have one as a standby device just for confirmation etc and just wondered what my options are. I've got an HTC desire which has GPS built in, and I have a Tomtom XL. Does anyone know of any cheap and easy solutions to using either of these? I've seen that memory map do CAA charts but I don't want to invest in something that is useless. I don't need anything other than a decent moving chart. Any ideas would be great - many thanks!

[Genghis the Engineer]

Search the forum, there's been many threads on this before.

G

[dublinpilot]

I believe the HTC Desire runs on Windows Mobile. Is that correct?

If so, you can use PocketFMS on it which does exactly as you ask.

Home of the PocketFMS Foundation. (http://www.pocketfms.com)

[wigglyamp]

Airbox AWARE - just shows your position overlaid on the 1/2 mil chart and warns you if you're going to conflict with Airspace. You must plug it into the cigarette lighter socket as the battery doesn't last very long.

[Fuji Abound]

Just another recommendation for PocketFms - it really is a super piece of software that works superbly well if combatible with the devices you list.

I dont use it myself in the cockpit these days because I have a MFD, but I do use it for planning and it would go on my iPad as a back up if only they released a version for the iPad.

[dublinpilot]

it would go on my iPad as a back up if only they released a version for the iPad.

As you know PocketFMS isn't available on the iPad, but there is a PocketFMS Airspace Avoid app available for the iPad. It is not near as advanced as the PocketFMS PC system (and probably not much use to you for planning), but it does act as a simple airspace warning tool. You can see your position relative to the airspace around you and get warnings if you are about to enter controlled airpsace along with the frequency needed to gain a clearance. You can enter a simple one leg flight plan.
AirspaceAVOID - Can you afford to fly without? (http://www.airspaceavoid.com)

The cost is about £11stg.

It's also available on the Android operating system.

dp

[VOD80]

Hi dp,

That Airspace AVOID looks good. Some of the screen shots show altitude. I guess that's GPS altitude. How does that compare with barometric altitude?

Cheers,

Tony

[Genghis the Engineer]

Hi dp,

That Airspace AVOID looks good. Some of the screen shots show altitude. I guess that's GPS altitude. How does that compare with barometric altitude?

Cheers,

Tony

Variably, mostly quite close, but you still need to fly to barometric altitude. It is useful (if you have a terrain map in the GPS) for terrain avoidance however.

G

[flyingguy1984]

I did search the forums, yes there has been many posts however technology changes so rapidly it often requires new input. I'm going to checkout the pocketfms thing, looks good.

I'm thinking possibly using a memory map and this app off the market place, though I'm not sure if the maps from memory are encrypted, as apparently this app will only read unencrypted maps.

[IO540]

GPS altitude should be very close (within say 50ft) to baro altitude if you have continuously set the correct QNH.

Just avoid units with the SIRF-2 chip, which have a constant ~ 200ft error, though all of those would now be quite old. SIRF-3 fixed this.

Memory Map is an OK solution for running a UK airspace map. It's no good for abroad; if you want a general European VFR moving map solution running proper VFR charts then you are looking at Oziexplorer and charts from bit-torrent ;)

[VOD80]

Io540 and Genghis, thanks, that makes sense.

I guess GPS versus baro altitude have to be quite close because they are both (simplistically) measuring the distance from the centre of the earth...

Neat solution!

[Fuji Abound]

Again as another plug for PocketFms (I have no relationship with them) their VFR maps cover the whole of Europe (and more) so they really are a one stop solution. They arent comparable with scanned maps offering much quicker refresh and a great deal of real time functionality - as always you get what you pay for, but I really do think PocketFms is very well priced for all that it has to offer.

[flyingguy1984]

Does anyone know where I could pick up a second hand garmin maybe? A portable one that is. I've had a look on the net but they seem to be impossible to find. Failing that the airspace avoid thing looks good.

[dublinpilot]

That Airspace AVOID looks good. Some of the screen shots show altitude. I guess that's GPS altitude. How does that compare with barometric altitude?


Tony,

Others have given you some of the limitations of gps altitude. However it is often device dependent as different hardware manufacturers correct for altitude in different way.

In order to counter act this (so that you have a correct altitude for airspace warnings) the PocketFMS Airspace Avoid app allows you to enter your real Baro altitude, and it then works out the difference and applies that difference for the rest of the flight. This should ensure that the altitude that it uses for airspace warnings is very very close to your baro altitude.

Indeed the more powerful PocketFMS system also allows for a similar correction for similar reasons.

dp

[B4aeros]

I think that TomTom use their own OS derived from Linux, so you won't get anything to work on that. Pocket FMS & SkyDemon currently only work on Windows devices.

Memory Map isn't expected to be available on Android until much later this year.

The MMTracker app uses the old file format; 2009(?) was the last year they were available. You can indeed find torrents for some 2005 charts which should work in MMTracker - if they're still being seeded.

Of the self scan options, OziExplorer (http://www.oziexplorer.com/) have an Android beta out. They also have their own copycat in Androzic (https://market.android.com/details?id=com.androzic&feature=search_result). My preference is for Orux Maps (http://www.oruxmaps.com/index_en.html).

A simple, free solution would be to use XCSoar (http://www.xcsoar.org/discover/screenshots/) from the Android market. You can set it up as purely a moving map, with airspace markings & warnings, without any of the gliding info.

http://dl.dropbox.com/u/925530/whole_area_MG.jpg

(not my image)

[IO540]

I guess GPS versus baro altitude have to be quite close because they are both (simplistically) measuring the distance from the centre of the earth...

Actually GPS calculates a 3D solution in space, which is related to a height above a theoretical shape which approximates the earth's shape (a slightly squashed sphere). This height is then remapped (in any half decent GPS, using either a lookup table or a polynomial surface) onto another theoretical shape which very closely represents the earth's "sea level" surface.

That's why a good GPS will read a very accurate altitude; usually within 20-50ft. GPSs which pick up the EGNOS satellite get even better than that; within say 10ft.

The reason one uses a barometric altimeter is for vertical separation of traffic.

But if you stood on top of some mountain and wanted to know your altitude, the best thing you can do (without spending vast amounts of money on gear) is a GPS with EGNOS capability (e.g. a Garmin 496). Forget altimeters... they read way off if the temperature is nonstandard and anyway where will you get the QNH to set in it?

[VOD80]

Thanks dp, I've downloaded the app and I've had a little play with it. Looks good!

And IO540 - you're right, of course - and I knew that... I'd just been playing around with using the GPS position to calculate track lengths and in there, you enter the earth's radius... hence my temporary loss of situational awareness :\

Cheers,

Tony

[BobD]

Another vote for PocketFMS. You can get a free 30 day evaluation copy from the website. I loaded it onto my HTC HD2, laptop, and home PC, and have been very impressed with it. My trial runs out next week, and I will happily shell out the €150 to license it for twelve months.

[Bobby Hart]

If you can find a decent windows PDA/nav device out there, then SkyDemon can be installed on it. Its a good solution if you or someone you know is technically minded...

[mikehallam]

The NATS AWARE mentioned above is a very good, inexpensive colour chart position showing GPS device. It has the free monthly CAA chart updates too.
[I understand 1/4 mill & French charts etc. are now available too].

Its Controlled Airspace warning and mapping is a perfect way to prevent "busts"

I've had mine a year and it's so easy to use. They sell bigger & better models too, but IMHO the original £150 model is perfect.

mikehallam