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Garmin Geko On A320 Airbus

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Flying back from Israel yesterday I thought to myself, "I wonder" and powered up my Garmin Geko next to the window.


It worked!!!


508 mph, 33,000 feet!!!


Anyone else managed to get their's to work on a plane? (oo er misses)


I'm guessing there may be a security implication wth this - could be very handy to know precisely where you are on a passenger jet; but I've not come across any security notices about GPS equipment.

Edited by kitefan
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I'm guessing there may be a security implication wth this - could be very handy to know precisely where you are on a passenger jet; but I've not come across any security notices about GPS equipment.

American Airlines don't allow them.



Devices That Cannot Be Used on Board

Radios - AM, FM, VHF, battery or cord operated TV sets, TV cameras


Electronic games or toys with remote control, except those installed on the aircraft


Cordless computer mouse


Portable Global Positioning System (G.P.S.)


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Slightly off this topic but I also have a Geko (301) and I have been interested in the speed recording. In my car it reports about 36mph when my car speedo says 40mph? Similarly in other cars it seems to be lower than the speedo reading.


Is this a car manufacturer's ploy to keep our speeds down or is there some technical reason why it is slower than your actual speed?


The Hokesters...

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By law car speedos are not allowed to read less than you are actually doing. There is a semi complicated equation for the allowance for reading over which I can never remember (but I bet it's on the internet somewhere)! As a general rule and I've used my gps onboard a number of different cars and motorbikes, you'll find a difference of about 5 mph at 70 mph.


Bear in mind though, before you take the extra 5 mph through those 40 mph road work cameras, the car speedo suggests what you are doing where as the gps technically is telling you what you've just done! It is also affected by the same errors which sometimes doesn't quite put you in the correct cache location!


PS. if you get stopped for speeding don't let the Police get hold of your tracklog!!

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There is a semi complicated equation for the allowance for reading over which I can never remember (but I bet it's on the internet somewhere)!

It's not too complicated and is +10% (and -0% as you say). Perhaps you're thinkiing of the guidelines generally used for PC Plod stopping people speeding of +10% + 2mph.


Most vehicles have speedos that come in at the higher end of this - i.e. the car will have to say >75 before you are actually doing 70. The knock-on effect of this is that when you sell your 65,000 mile car it's probably only covered 60k!


Of course if your speedo has gone faulty and is under reading and says you're doing 69 but you're actually doing 80 and you get stopped that's no defence - you'll still be done :(



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I have a 93 cavalier, and at 70 on the speedo, the GPS says 65......and when I reach 70 on the GPS, the speedo says 77.....but when our 96 Citroen Xantia says 70, the GPS says 72! One on the right side of PC Plod, and the other not!!

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KLM, allow them. :( On a recent visit to friends in Minneapolis I had the GPSr on sitting at the window and couldnt help notice I was directly over my own house. :D I had flown out of Edinburgh to Amsterdam, Amsterdam to Minneapolis. So I fly all the way over England, the Channel and into Amsterdam just to wait 5 hours on a fight to take me back over the Channel up through England and back over my own house. :D Boy did that s**k when I saw that. I did get a reading of max speed 660mph. :(

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Mines been on the plane from Inverness to Gatwick a couple of times. Its interesting to see how quickly you get to London and then spend about 25% of the flight going around in circles over Brighton.

Trains are quite good too. The HS 125 actually clocked 126 mph according to my GPS! The tracklogs look interesting - the tunnels show up very clearly.

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I just returned transatlantic from the UK, and route marked the whole way back from Gatwick to Philadelphia in an arc more or less direct slightly north then south along the Canadian and US coast. Oddly, I had marked the same flight last year, and that one was much farther north, up past Glasgow into the North Atlantic, before heading down past Newfoundland. Maximum speed 650 mph and altitude of 37796.


On USAIR, no one batted an eye about the GPS up to the window.

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The best advice is to check with the airline first. I got the OK from Virgin ahead of a particular journey and my Meridian Platinum with maps was a constant source of interest to the cabin staff during the flight to San Fransisco last year.


Once they'd understood what it was, I was constantly asked throughout the flight where we were, how high, how fast etc. They were particularly impressed how I could point out the various towns and rivers etc. we were passing over.


I have to say I got the best in-flight service ever on that flight :blink::blink:

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Anyone else managed to get their's to work on a plane? (oo er misses)

Yep, all the way to Australia. I switched it on every hour or so and then saved the track at the end of the flight. Saving it joined up all the segmented tracks and filled in the gaps. It worked really well, up against the window, with a pillow in front of it and me leaning against it to hold it there.

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On the car speedo question there are several things which can cause an effect on the indicated speed on a car's speedo. Firstly you need to understand the speedo works by measuring how fast the wheels - more accurately the prop shaft or equivalent - is going around. They have to assume the wheel has a constant and known diameter to convert this to a speed reading.


But wheels have tyres that need inflation, and varying pressure changes the diameter, hence the speed reading. Tyres wear - only by a percent or two - but that again will change the diameter. So does the load in the car - higher load and the tyres squish so the effective diameter is reduced. Effective diameter being the distance from the ground to the centre of the wheel. Plus as tyres spin faster they increase in effective diameter as a consequence of centripetal (cf centrifugal) force. Different tyre makes/types have different diameters - again slight but an effect that needs to be taken into account.


Makes it all the more amazing that speedos work at all!


If I remember correctly on my cars the odometer (measures total distance travelled) is more accurate than the speedo. I suspect the legal requirement on a speedo not to underred does not apply to the odometer - so they can be made with a +/- tolerance allowing the effects I have mentioned - in part - to cancel out.


Some track cars have a dopler radar speedo that eliminates all of the effects, but they are expensive.

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You forgot to mention the eminent role of transmission-slip on speedos. It has a large effect at velocities above 180 km/h. The transmission-slip and therefore the measuring error can range up to 8% - that means 20 km/h deviation at 250 km/h

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Done it, Recorded, 508mph on a decent into Stanstead on my Meri Plat..airline not mentioned but was a 737, and I was sitting next to window, am sure they thought gps was a gameboy or similar. The mapping aspect is brill, as on a clear day you can look down and follow your progress over the country. Am I sad or whit?..Doh! but just enjoy it anyway! Cheers DD


oh! ps As per a previous post and well covered, the exact speed (you think) your doing in your car can be influenced by a few psi in your tyres.

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I tracked all the way back from greece on my Etrex Venture, had to switch to battery saver though. Excell Airways in a newish 737 800 series, they did not say a thing, hit 555mph and descended 7500 metres over the width of La Manche. Flight path down into gatwick and then the terminal was as straight as a dye apart from 3 small turns. The final line up for landing was impressive.

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