What GPS?

[Evo7]

To my surprise this doesn't seem to have been asked here before (or else I can't work search ;) ). Anyway, I was chatting to an friend who is looking to buy a GPS for use while flying a spamcan around the south of England. I know nothing about them and he is offline, but I said that I knew a place to ask....

Budget will stretch to around the price of a Garmin GPS195 (i.e. roughly £700) but he would prefer to spend less. It needs to be handheld as he rents aircraft, and other priorities are ease of use and ability to run off batteries. Moving map would be 'nice' but he isn't sure if it is worth the money.

Obvious candidates are the Garmin GPS195 and GPS-III Pilot and the Bendix/King Skymap II (although my research runs no further than the Harry Mendelssohn ad on the back page of Pilot ;) )

Thoughts?

Cheers :)

[Cat.S]

I've been using a Symap II (c. £400) for six months now in rented aircraft and love it. I strap it to my left leg and prefer the large size screen as it's easy to see at a quick glance, therefore allowing more time to look outside. Before choosing this one I got hold of the screen sizes of all in my price range and made little cardboard blanks to scale. The Skymap II was a clear winner here. The moving map is great after being given an ATC induced diversion and it's a fantastic back-up to traditional navigation methods.

[Wrong Stuff]

Cat.S - do you have to use a remote antenna or does it work fine in your typical spamcan without? It looks to have a nice size screen but I'd hate sitting in a cats cradle of wires.

[slim_slag]

Of course, these should only be used as backup to situational awareness obtained using other aids like NDBs ;), but if he doesn't want to spend too much cash and when all else fails still know exactly where he is, you cannot beat

Garmin 12XL (http://www.garmin.com/products/gps12xl/)

You can block the signals just by putting it between your legs! They do sell external antenna for a huge percentage of the cost of the actual unit.

[Wide-Body]

Have been using a GPS 111 pilot. the dogs B*!!*cks. Capability vs price very very good. If you can see the sceen (Other kit has bigger screens) then I can find very little wrong. Have been all over the world with one

Regards

Wide:)

[Rattus]

...or you could try looking over the side :D :D :D

[bcfc]

Whilst keeping the map as my primary means of nav, I have had a GPSIII for a few months and can't fault it (except my bungy fingers and the little buttons sometimes come into conflict). I have it sitting on the right hand side of the cowling and generally only ever use it to confirm my position or, more often, help work out ETA's and drift.

It has gone loopy on me a couple of times, once when coming back to a small field in the states with less than perfect vis and I knew it was pointing at least 30degress too far right. I ignored and got back safely. They're not perfect but they're superb in ridding the nagging doubts about my own navigation. I rarely fly without one now and the GPSIII is a nice compromise between functionality and battery life. I get 10 hrs or so from 4 AA's.

If you fly high wing, I'd recommend getting an aerial extension but haven't needed it in low wings. The only other accessory I ever use is the bean bag mount. Well worth the extra £10.

[Shaggy Sheep Driver]

I use a 'Pilot 111' in the Chippy, velcrod onto the RH side of the coaming using a small wooden 'former', shaped underneath to fit the curve of the coaming, and flat on top for the Garmin mount.

It works a treat. Very useful for groundspeed and reporting point estimates, and as a back-up confirmation of position. I only once saw it fail - in an AA5 over the Lake District. We had 2 'Pilot 111's on board, and both went 'zero signal' from Morcambe Bay to the Solway Firth - so don't rely on it!

SSD

[FlyingForFun]

If money's an issue, tell your friend to spend his hard-earned cash on flying instead!

I've logged nearly 10 hours in my Europa so far, the first aircraft I've flown with a GPS. (Well, second actually, but the first was a rental that I didn't have use of for very long, so never bothered to learn to use the GPS.) Already, I've noticed myself becoming very lazy, and refering to the GPS instead of the chart. And, as a result of that, I'm far less certain of where I am. Yes, I did say "less certain of where I am" - the GPS is fine for getting you to an airfield, or finding a motorway, but as soon as you move away from the features which are on the GPS, situational awareness goes downhill very quickly, in my limited experience - and it'll show when your pax start asking what that town is down there, or how far you are from something which is off the edge of your moving map.

I'm now getting into the habit of selecting a mode on the GPS which doesn't include any position information, so that I'm not tempted to "cheat". No doubt that GPS can be a useful backup, but I don't like them. Unfortunately, I can't turn mine off, since it doubles as a radio. (It's a Garmin 430, by the way - so not suitable for your friend since it's not hand-held.) If it was my choice, I'd put a couple of VOR/DMEs and an ADF in an aircraft, and, for VFR flying, would only turn them on if I became lost.

Sorry,

FFF
-------------

[englishal]

Get a cheap Garmin eTrek for around £100, then go to aeroplanner.com and download 'data chunks'. These data chunks contain waypoints of VORs / NDBs / Airports / VRPs / intersections etc etc. Once these are on your GPS you do not need a 'proper' moving map, and in fact they're probably more accurate than most moving maps you get on handheld GPS's. It also saves you getting a Pooleys GPS companion and typing all the WPs in.

I did a comparison between the handheld eTrek with waypoints from Aeroplanner and a (cantrememberthenameof) panel mounted IFR certified GPS last time I was in the US. It was spot on.

The eTrek is 12 channel same as most GPS's on the market so accuracy will be or should be exactly the same as a more expensive model. If you're feeling particulaly flashy, spend another £100 and get the eTrek with barometric altimeter built in...

Cheers
EA

[Evo7]

(Aaaagh - first reply lost when PPRuNe decided to log me out when I hit Submit Reply :mad: )

Thanks for the feedback so far. It seems to be a choice between the GPS-III and the Skymap-II, which I guess I expected. We're going to go and have a play in Transair at the weekend, but it's not easy to guess if something that's cool in the shop is still so good in the cockpit, so it's good to have some views.

FFF - Money isn't too much of an issue, and the budget just came from skimming through the Harry M. advert and seeing what price caused him to start to sweat. He's a fairly recent PPL with 70-something hours, and is just starting to look at leaving the local area and those familiar airfields visited during the course of the PPL. The club aircraft all have VOR/DME and ADF equipment, but GPS is just something else to hold his hand.

(edit: forgot to ask, what is the difference between an 'Aviation' GPS and an 'Outdoor' GPS such as the 12XL linked above. The aviation ones seem far more expensive - no surprise there - and presumably come with waypoints loaded, but is there any practical difference if you just need position and distance/track to waypoint?)

Oh, and I know that real pilots only navigate using a sextant and one of John Harrison's chronometers... :)

[Hairyplane]

THe Garmin 100 has been around for a few years and are appearing on the secondhand market for less than £200.

A terrific piece of kit - no moving map or database but kids stuff to programme/ use. These were quite expensive new.

Mine got me to Stockholm and back the other week.

THe Pilot 3 is incredible value - I have just bought one to stick in my pocket if my map blows out of my open cockpit plane.


They do make you lazy - I make a point of not using mine occasionaly ( usually when I am staying in the circuit...!)

So - if you want new - Pilot 3. If you can find a 100 - go for that and spend the change on flying.

[distaff_beancounter]

Evo7

I think that the difference between Garmin GPS models, are:

"Outdoors" is designed mainly for walkers, climbers, etc, & shows towns, roads, footpaths etc.

"Aviation" are designed for aircraft use, & has a database, of airfields, controlled airspace, etc. You can then buy regular database updates from Garmin, for a fee, for your GPS.

The "Aviation" model is well worth the extra cost, as it gives you far more relevant information, eg nearest airfield, (if you are having a panic!) & whether you are about to infringe controlled airspace. Without the aviation database, you would need to do a lot of data imputting yourself, in order to get anything useful out of it.

[Whirlybird]

I'm very happy with my GPS III Pilot which I've had for several years. It can make you lazy, but I find it invaluable in the following circumstances:

1) Your route is taking you very close to controlled airspace that you'd rather not infringe.

2) You'd planned to fly overhead an airfield; the cloudbase won't let you, and they tell you to route around; you think you can judge 2 miles fairly accurately, but you'd like to be certain.

3) The weather's deteriorated unexpectedly; it's safe to fly, but nav is difficult and you'd rather not get too overloaded when you may need your wits about you should things get worse.

4) You're overloaded in some other way, eg you just scared yourself by getting too near another aircraft or something similar; why compound things by getting lost too; switch on the GPS and make things easy for yourself while you calm down.

Otherwise, I just carry it in case I need it. I don't know how to do anything other than follow the moving map; I did once, but I forgot through lack of practice. But I like visual navigation, and my way saves loads on batteries. :D

[Circuit Basher]

I'm afraid I'm with FFF and Whirly in the 'dinosaur' camp - the only time I've flown with a GPS with moving map, I spent a lot of time with my head 'down' (even though the display *was* at coaming level); some of this was tinkering with the new toy, but partly I was just being lazy.

I did use it to skirt between Southampton CTR and a Danger Area as I was flying to Thruxton - ISTR there was a relatively narrow 'corridoor' of 3-4 miles at one point that I had to be quite careful not to stray too far either way (and there were few VRPs and a fairly stiff crosstrack breeze on that day!).

Other than that, give me a good VOR and ADF and I'll be happy; I'm a bit disappointed that the group to which I belong have just voted to use this year's avionics budget to install GPS (rather than fix the broken VOR and put in an ADF!). Looks like I'll have to use another hairyplane for my IMC rating!

[Shaggy Sheep Driver]

CB - I think you'll find the 'fiddle factor' goes when you get used to it - I just give mine the occasional glance, now.

Whirley - try setting up routes using waypoits. It's very simple (the Garmin handbook is not the best, but it's not too bad) and can be a great help to see how far off track you are (or not)at a glance if the cockpit load is high. This also gives you accurate continuous readout of time and distance to next waypoint - very useful for ATC estimates.

Also, in the Chippy there is no room for Pooleys etc. On the Pilot 111 just click on the airfield on the map and you get all the info - freqs, runway layout etc. Useful if you need to divert or if you fancy dropping in somewhere you hadn't previously planned.

SSD

[pulse1]

Having used the GIII I bought a second hand Garmin 195 for about the same price and I think that the larger map makes it a lot easier to use.

One of the most useful functions I find is during flight planning. I can simulate my intended flight at high speed, following it on the chart and GPS. This has improved my flight planning and has increased my confidence a lot, particularly when it comes to staying out of danger areas and controlled airspace.

[What a Loop]

I have used the Skymap II now for a year or so and find it great as a back up. The large screen makes it easy to read, there is the issue if you plug it into the cigar lighter and having the external antena you do have a lot of wires about, but if your careful in setting it up its okay.

I have found it very useful on occasions when I have been tracking close to the danger area's near Thruxton for ensuring that I don't accidently encroach them.

As a back up I can find no better, but I do agree that you can get lazy and start to look at them to see where you are. But a little will power and keeping a constant look out is much more fun than staring at the screen:rolleyes: :D :D

Sometimes I fly without it but most times I like to know its there just in case.

I know you said cost isn't an issue but occasionaly Harry Mendelssohn have reconditioned units at very reasonable prices, so its worth asking. All completly refurbished at the manufacturer.

[Chuck Ellsworth]

I have just returned home from three weeks flying in Europe and just can't resist commenting on some of the ideas posted here about GPS.

Aviation like all other human endeavours evolves with time by finding new and better means of accomplishing the task.

GPS is our newest and most accurate and reliable navigation aid.

To remain fixed in the belief that VOR and ADF are the nav aids of choice would indicate that you should disregard wheels and just drag your vehicle over the ground.

To keep reguritating the mantra that one should rely on your map is just to simplistic.

A truly professional pilot will use whatever aids he / she has at their disposal to the best advantage of the task at hand.

GPS is the best aid developed to this point in time.

................


:D The hardest thing about flying is knowing when to say no.:D

[FlyingForFun]

Chuck,

You said: "GPS is our newest and most accurate and reliable navigation aid"

I agree, but with the emphasis on the word aid. The primary means of navigation for VFR flight is looking out the window. And, as I said earlier on the thread, just having a GPS turned on, even if you don't intend to use, can decrease situational awareness by reducing the (perceived) requirement to look at ground features out the window. GPS is not as detailed as any VFR chart that I've ever seen - in many cases, it can pinpoint your position precisely in the middle of a black screen with a one or two blue lines, which doesn't help very much.

The same can not be said of the use of VORs and NDBs as nav-aids. These require cross-references to a chart, and therefore require the pilot to maintain situational awareness. Which is why I prefer them.

I have flown with "GPS Pilots" (I use the phrase in quotes to mean "a pilot who flies the GPS", as opposed to pilots who use the GPS as an aid) who have been unable to identify large towns that they were overflying, because the town was not shown on the moving-map screen. I don't want to become a "GPS Pilot", but already, after just 10 hours of using a GPS, I've noticed myself going down that route, and I'm having to take active steps (like switching the GPS to a different mode) to prevent that from happening.

FFF
---------------

PS - Evo, sorry to hijack your thread with a pros/cons of GPS argument - it wasn't intentional, honest!

[Evo7]

No worries mate - wandering off-topic is half the fun. Anyway, it's not something I'd have thought of, so useful info. Right now it's chart and stopwatch for me, at least until I get through the skills test. Then I might buy myself a present too ;)


Completely off-topic now, but Chuck - Amazon.fr have finally got around to delivering my copy of Un vol de légende sur les traces de l'aéropostale (on the third attempt, after delivering a road map of Limoges and then a porn film :eek: :rolleyes: - I think the latter was 'repayment' for a strongly-worded complaint about the roadmap. Somehow I don't think they like English customers;) ). Many thanks for the recommendation :)

[englishal]

I agree with the comments posted by Chuck. Just one point to add to my other post....

If you want a really good, cheap moving map GPS system, then you may want to consider hooking up a cheap 12 channel GPS (such as my trusty eTrek) with some pocketPC device such as the Casio Cassiopeia. There are several packages on the market which run on these PocketPC devices, but the favorite I use is a program called Ozi Explorer. I can't remember how much it costs, but its cheap. There are two flavours, one which runs on the desktop, allowing flight planning and easy creation of routes and the like, and the one that runs on the PocketPC device. Maps and charts can either be scanned in and 'calibrated' or downloaded from places like Aeroplanner, already calibrated for use. I just downloaded a US World Aeronautical Chart for the UK, ok its the US flavour of chart, but it gives a great full colour zoomable moving map system.

I also use another package called Anywhere Map, which is a vector chart system. This is a EFIS type of system, which is excellent, though you do need to subscribe to the database updates which adds to the cost slightly.

All in all the cost of a complete system like this is in the region of £600 to £700 including stuff like Casio and the yoke mount for the Casio....

Cheers
EA

;)

[GRP]

I started off with a Pilot III, moved to the Skymap II because I thought the larger screen would be better and now have a GNS430 fitted in the aircraft. My personal opinion of those two handhelds is that the Pilot III is the better of the two simply because it is so much easier to use in the cockpit, not requiring an external antenna for example which I find causes a bit of wire congestion in the cockpit. The one thing I like though about the Skymap is the 'position' field which gives you something you can simply read out when reporting a position ("4 miles NW of Exeter"). The GNS430 is excellent, though obviously stuck to the aircraft! One of the disadvantages of that is that you can't set it up at home beforehand. However once in the air, and coupled with the autopilot it significantly reduces workload.

I still plan most flights with the chart and work out headings and speeds based on the forecast wind (unless I'm just following the coast for example) and I then keep the chart on my lap so I can check where I am as I go. I can't see how this possibly reduces situational awareness though. I always know where I am but do not have to keep looking for roads and railway lines to check! I even get time to get the odd fix with the VOR and DME to check that they are working properly in case the GPS packs up!! :-) The other really great thing is that you can plan a flight fairly close to controlled airspace and be sure you do not infringe it. Quite a few routes from where I am based clip the edge of either the LTMA or the Solent zone and I can now quite happily plan a route that goes right to the very edge without having to plan a detour around in case my DR doesn't work out (EGHR-EGMD for example goes right past the bottom corner of the TMA at anything above 3500 feet and prior to the GPS meant I would always route via SFD to avoid the issue).

[Whirlybird]

As many of you know, I recently spent some time flying out of Long Beach, California. When I finally dared venture out alone into the wilds of LA, I flew up to Santa Barbara to visit a friend, taking a nearly qualified PPL to keep me company. Everyone had told us to follow the freeways to leave LA, as they do out there. Well, as Brits, one freeway looks much like another, and in the LA smog we momentarily became...er...unsure of our position. "Hold on", said Nick, "I'll find it on the GPS. Well, as he fiddled I thought - that looks like a coastline emerging from the murk, the compass says we're heading West, we should be going North, we could be in controlled airspace in seconds, and less than five minutes ago I knew where I was, so let's go back to there and look for a freeway that goes roughly North. I did, and it worked, while Nick still fiddled with his GPS.

The point is, basic navigation principles will work anywhere, even when you're in the middle of a 60 mile square sea of concrete in poor vis. But ONLY if you're up to speed with them, enough that it's second nature to note the time, note the compass heading, and so on. And GPS isn't much help in LA, or didn't seem to be.

So to my mind it's not GPS v map and compass. It's fine to use both, but too many people who use GPS forget how to use map and compass competently. And most of us reading this forum haven't been flying for as many years as Chuck, who likely as not couldn't forget if he tried. :D

[GroundBound]

Something nobody's mentioned so far ... the cost of keeping the GPS database up-to-date. The Garmin GPS Pilot costs about 450GBP, but you still need to count another 295 USD per year for the monthly updated Jeppeson database.

Flying with an outdated database is as bad (dangerous?) as flying with an outdated map. If the cost is too high, its tempting not to update - bad idea :(

[Chuck Ellsworth]

Let me try again to enlighten those of you who may be stuck in the ab-initio flight training mindset.

When you plan any flight you use " ALL " information and aids available to you for the planned flight.

Some of us fly in areas that just will not allow navigation by reference to a map. I defy anyone to map read in the Sahara desert or over the open ocean.

Last week we flew from Seia Portugal to Bordeaux France, in addition to VOR we had a panel mount Garman 430. I " Always " run two handheld GPS units, a Lowrance Airmap 300 and an Anywheremap running on an Ipac computer.

The aircraft was new to us and we had not tested the avionics so we flew VFR.

We also had two maps that we were monitoring for added situational awareness.

However the bottom line is of all the means we had to determine where we were and where we were going the GPS receivers were the most reliable and accurate...Period...

Having said that you should of course " always " cross check your position and where you are headed by reference to your map..

Have fun.

Cat Driver:

[englishal]

I don't want to become a "GPS Pilot", but already, after just 10 hours of using a GPS, I've noticed myself going down that route

Same is true when you become IR'd. I'd file IFR in the US just so I don't have to look at a VFR chart, especialy if flying into an unfamiliar area (airspace magically disappears)........after all IFR charts are hell of a lot simpler, and so long as you file for a reasonable altitude you're not going to run into any cumulogranitus :D........

oops, sorry off topic.....

EA ;)

[Cat.S]

Wrong Stuff- I use the remote antenna which has a rubber suction cup which I stick to the bottom left of the Tomahawk screen. I've only used it 16 hours in the air, but haven't had any satellite acquisition problems with it yet. As the GPS is fastened to my left leg anyway, there isn't much of a wire congestion problem as it's long enough to route safely round obstructions. In 8km vis, with somewhat variable side winds, its been a great confirmation of position, especially in the southern end of the LLR.

[slim_slag]

However the bottom line is of all the means we had to determine where we were and where we were going the GPS receivers were the most reliable and accurate...Period...

Now SA has gone, I have found you can fly a "precision approach" using a handheld Garmin 12XL GPS, local altimeter setting (and safety pilot). Even altitude reporting is pretty decent now.

I have even seen approaches where if local altimeter is not available, the ILS or VOR has higher minimums than the GPS approach - if authorised at all!!!

Next time you taxi onto the runway for departure, request a 30 second delay while you get a good position stored, then see if you can find your way back.

And GPS isn't much help in LA, or didn't seem to be.

LA is a good example of where GPS is more useful than normal. As you said, it all looks the same from the air, visibility can be less than ideal, and there is complex airspace to negotiate. You might need to set up your route in advance but once you do you always know where to point the nose.

[BRL]

englishal Do you have a picture of your set up?

[slim_slag]

I have even seen approaches where if local altimeter is not available, the ILS or VOR has higher minimums than the GPS approach - if authorised at all!!!

Ok, I've got some out of date plates from my car, but still within 6 months old.

KHDN (Hayden Colorado). Approach type and DH/Minimum

ILS/DME - 6837 MSL
ILS/DME circling - 7640 MSL
LOC - 7640
VOR - 7320
VOR Circling - 7660.

But

GPS-C, 7220 MSL.

The comments on the precision ILS approach say it is not authorised if local altimeter not available. Neither is the LOC or the VOR. The GPS has no such restriction.

The GPS approach has the second lowest minimums, only the straight in ILS/DME allows you to descend lower.

Interesting stuff!

[White Shadow]

For Cranfield visitors this w/e -
Annexe C of the AIC has a list of Waypoints co-ordinates for punching into a basic GPS, then punching "goto" whichever one you want, for a check on basic, ded-reckoning and map-reading.
(NOT a good idea to use a moving-map thingey in the Rally environment...)

I bought a Garmin 45, years ago - the marine version of the 95, and very cheap. Max ground-speed 99 knots; that's about my VNE nowadays...
A useless moving-map on the small screen; a "man-overboard" feature for instantly marking a position to return to: no data-base - I've punched in the co-ords of all the places and waypoints I think I'll need - but it really has all the basic stuff for VFR flying. Addictive, though, if you're lazy and not careful.

I find it useful in murky weather, for a check on my track-keeping in featureless areas. or with variable winds. And when you KNOW that waypoint MUST be right here, right now, the little arrow on the screen says "right there on your left, blockhead" (ie in your blind spot, at that moment).

I just sit it on my lap. and the AA batteries seem to last for ages if I don't fiddle with the buttons much.

Horses for courses, really.

WS

[Julian]

Sometimes we seem to be a bit anal when it comes to GPS in the UK, at the end of the day you should use all information availiable to yourself. If you have a map and GPS use them to compliment each other! What happens if you map flies out the window, gets covered in coffee or eaten by your 5 yr old nephew when you werent looking! :)

In the US GPS use is commonplace, I regulary use GPS when over there but backed up by charts so I keep my situational awareness and that goes for wether I am flying under a VFR or IFR flight plan.

GPS approaches are also possible in the US with the integrity of the systems being confirmed using RAIMS before the approach is commenced. Note : We were using an IFR certified GPS system with current database. If anyone gets chance to do when sometimes whilst they are in the US then give it a go, even if you just get an Instructor to show you one.

Did you manage to try one Whirly?

We regulary took up a handheld Garmin eTrek with barometirc alt (£130!), for interest and as pointed before there doesnt appear to be any difference between these and expensive ones for telling you where you are.

I am now playing with it by hooking it upto my laptop to provide a full colour moving map display on a 14" screen :)

Julian.

[Biker Pilot]

Slightly off topic, but...

I have a GPS III Pilot which I use mostly in the US as the 172 I hire from The Pilot Centre at Denham (as in "172 in West London" thread fame) has a Garmin 250XL fitted, though I find the only time I usually look at it is to change COM frequency.

Anyway, I mainly use my GPS for flight planning and have noticed several anomolies with the database concerning sizes of airspace regions in that several ATZs are shown as being about 5nm or so radius. The last version I installed (went out-of-date last week) has Farnborough and Wycombe Air Park, among others, at this size (the latter is showing as overlapping with the London CTA!

This suggests that it cannot be used to guarantee you are flying clear of controlled airspace unless you have checked before your flight that the database conforms to your map. Anyone else find this?

Regarding other points put forward:

Why do you need to update the database every month? You only update your map once a year, after all. If there are changes to airspace, frequencies, etc, then you will be able to pick these up as you go from NOTAMs, etc, just as you would for your map. I only intend updating mine each time I move between the UK and the US. (Am I being terminally naive here?)

I agree that the feature of being able to "fly" your intended route on the GPS in the comfort of your armchair at home is great.

My GPS seems to have a selection of roads, railways and towns almost everywhere in the world as well as the Europe/Africa Jeppesen database, however it has NO map info for America! No towns, freeways, nothing except the state boundaries and state capitals. Is this what I should expect? Just seems a little strange to me.

BP

[Evo7]

Thanks again for the thoughts so far. Another question - if you buy a moving map GPS, what is the coverage of the map like?

I'm guessing that while you're dodging Gatwick the GPS can't also contain a detailed map of Burkina Faso and the Ouagadougou TMA, so where does the map end and the region marked 'here be dragons' begin? And if you buy one in the UK and then head off to Florida do you then have to pay up for another chunk of the Jeppesen database?

Sorry if this is a dumb question - as I said, I know nothing about them :)

(edit: as if by magic, the previous post appeared after I started typing :) )

[Biker Pilot]

Evo7,

The Garmin GPS units, at least, are based on a split of the world into 3. The Americas, Europe/Africa and Asia/Pacific. Personally, I'd prefer the ability to mix and match smaller regions so I could choose Europe and North America as one. I have dealt with the nice folk at Jeppesen regarding databases and they do offer all sorts of regional/detail choices. It's just that Garmin don't pass those choices on.

BP

[englishal]

No, but I'll take one....

EA

[FlyingForFun]

Chuck,

Yes, I think you probably have a good point re. navigating across the Sahara, or the open ocean. My comments are limited to my own experience, which consists of flying around urban areas such as south-east England, or mountainous areas such as Arizona, where there are plenty of visual navigation features.

The only time I've ever been glad to have a navigation aid available as a backup was when flying across eastern California in a sand-storm, with visibility of about 8 miles - although I could still make out the shapes of moutains vaguely through the sand, there were no good navigation featuers, and it was nice to have a VOR/DME to confirm that I was on track and on time. I didn't have a GPS in my aircraft that day, but if I had, I probably would have used it, since it would have been more accurate than the VOR.

Like any tool, GPS can be useful, although I still believe it's overrated and can be detrimental to VFR flying in some cases.

Biker Pilot, I think you must have the same GPS database as me - but since I don't use it much, the errors don't really bother me!

FFF
------------------

[Whirlybird]

Julian,

I didn't do much with a GPS in the US, as I was mainly flying helicopters at low level, so looking out for kites and birds and wires was far more important!

Evo and others,

When I did take my GPS, on my first US solo cross country, I discovered the same thing; not much info, though I think airfields were marked. I hadn't known that either.

I haven't updated mine since I bought it 4 years ago, but I only use it really if I think I'm lost or can't find an airfield, and they haven't moved airfields or towns, and I only use it to back up my map reading. If my map falls out the window, I can either land my helicopter, or get a heading to the nearest airfield from London Info or someone similar.

I think this really comes down to using what's appropriate to the circumstances and being prepared to be flexible. If I was flying in the Sahara, round the world, the Arctic, or anywhere similar, I'd get two GPSs and loads of batteries. Low level in LA, and going to the PFA Rally on Friday, I won't even switch it on as I reckon I need my eyes out of the cockpit as much as possible. Most flights that most of us here do are somewhere between those two extremes and it's a useful but optional backup.

[GRP]

The point for me at least is that if you are flying with an up to date chart and have drawn lines on it and worked out your expected headings, then the GPS, assuming you can get it into a CDI mode of some sort by getting it to fly to a waypoint, will give you a very accurate way of flying your planned route. I don't generally have any airspace data, roads, towns etc displayed as they just clutter up the screen. If the line on my map shows it will clear controlled airspace then I fly along that line on the GPS, or slightly to the opposite side of it to the airspace then I am clear of controlled airspace! It doesn't matter a jot whether the aviation database is up to date or accurate! The airports and VOR's that you use as waypoints are unlikely to have moved!

So.... using a GPS, except where you are flying a familiar route in VMC with some sort of obvious ground features like coastlines or roads that you can recognise, you still surely have to draw lines on a map and work out your expected headings. Once you get in the air the GPS is a far more accurate way of making sure you are flying along the lines you drew than dead reckoning.

If you just launch with the GPS and its map as the only thing you look at you are probably going to get lost from time to time.

[FlyingForFun]

GRP, your post makes a lot of sense, thanks. I think I might try your suggested technique the next time I'm doing a cross-country of any distance to see whether I like it in practice!

FFF
-------------

[GRP]

Having thought about this since I posted that, I suspect there is a confusion as to what we mean by our 'primary' means of navigation. For my money saying that GPS is my primary means of navigation means that once I am in the air I use the GPS as the means of determining whether I am on track, rather than using VOR, ADF or dead reckoning. None of this for my money means you should not draw lines on a chart and follow your progress along those lines when you are in the air. I certainly do not mean that I use the GPS map to avoid the need to use a chart! In my case I have an autopilot coupled to the GPS and can have the track error from the GPS displayed on my normal CDI instrument. So the map on the GPS normally displays where I came from, where I am going to and a pink line in between with hopefully a little aeroplane on it sitting on the line pointing somewher in the direction of the line. It also displays the odd airfield en-route if they are large enough for my settings to allow them to show up. Occasionaly you see a wobbly line on it which is a coastline. Sometimes I have the airspace displayed so I can see when I am reaching the FIR over the channel. I can change the detail displayed by repeated pressing of the CLR key. Works for me, and as far as I am aware, minus the autopilot coupling, can all be done with the Pilot III.

[Who has control?]

Being a cheap-skate, I bought a second-hand Magellan. If I'm flying from A to B, all the GPS will tell me is that I have to turn right or left a bit, I've still got X miles to got, I'm doing Y ground speed & I'll get there in Z minutes.

It won't tell me where I am, which is great because it means I have to look outside and at the map. All it will do it to make sure that I am on track, following the line on the map.

[GRP]

Where you are is probably X miles back along the track you set up and offset by how far it says you are off track! Bit like getting a fix from a VOR and DME I suppose!

[englishal]

BRL,

there are a few pics of my Casio MM setup here (http://www.digital-reality.co.uk/GPS.htm)

Cheers
EA

[BRL]

Thanks Al... :)

[Chuck Ellsworth]

I would like to make one more comment regarding the safest, easiest and best way to fly from A to B.

For me the easiest and most comfortable is to apply take off power and rotate to the correct deck angle as I enter cloud just after lift off. As long as I stay in cloud and follow the clearance issued and read back I am as safe as Aviation will allow. A plus is to have either the Airbus or Boeing PFD and ECAM to make life even easier.

With the foregoing I can toss my sectional map in the back pull out my latest picture book and look at the pictures, until ATC askes me some trivia like squak ident.

So there you all have the easiest way to navigate. ( By the way both Airbus and Boeing use GPS as one of the nav aids being compared against the older methods. )

Cat Driver:

,,,,,,,,,,,,,,,,,,,,,,

:D The hardest thing about flying is knowing when to say no.:D

[Hersham Boy]

Chaps - can anyone recommend a good WWW site that explains more of how GPS systems work for aviation?

I'm wanting to buy one (love gadgets), but I'm not sure whether to go for an EnglishAl kind of setup (prob an iPaq plus some sort of receiver) or to go for the all in one incl. database kind of thing (Skymap, Pilot III etc.)

For what it's worth on the "why not buy a cheaper civvie GPS unit" question, I have a Garmin GPS II (use it on the m/bike and have all local GATSOs prog'd in as waypoints) this unit actually shuts off at 103mph. Thi is going to make it useless even in a C152! (and on a Fireblade ;) )

Cheers
Hersh

[englishal]

The one thing I'd say about the setup I use is that its very easy to change software, update databases cheaply, customize etc. If you go for a purpose built portable aviation GPS unit then you're stuck with it and its software. Also you're somewhat limited in that database updates are only available from the GPS manafacturer. There is constantly more aviation software becoming available for the PocketPC all the time. For example in the US you can interface the PocketPC with a GPS receiver and also with a receiver which gets weather radar images transmitted from the ground in almost real time and overlays them onto the moving map.

Virtually all moden GPS receivers are the same when it comes to accuracy in the form of position, so a cheap £100 unit will generally give as accurate results as a £1000 unit. I've had a $90 eTrek operate at over 200kts with no problems. If you're planning IFR flight then of course you have to go for a panel mounted IFR certified jobby, and keep the database up to date.

With the iPaq you can get a Compact Flash GPS card which slots into the unit which looks pretty cool. For around £800 inc the iPaq you get something which in my opinion is better than any portable aviation GPS unit.

If anyone is interested, you can find out how GPS works by taking a look at http://www.howstuffworks.com/gps1.htm

Cheers
EA