How easy is GPS?

[Carlito]

May be a stupid question but I've never used a GPS flying.
Say under normal PPL exam conditions, you're diverted. You draw a line on your chart, you get out your whizz-wheel, you account for wind and variation and off you go.
What do you do with a GPS? Bring up the new destination, hit GOTO and the heading appears? Do you have to account for wind? If you don't will you fly a side to side pattern like tracking a VOR without laying off the drift?

Basically I'm wondering how easy is it?

Thanks in advance,
Carlito

[FlyingForFun]

Can only speak for the Garmin 430, since that's the only GPS I've used, but yes, that's basically it.

Press the "Direct" button. Then enter the ICAO code for your new destination. If you don't know the ICAO code, you can enter the airport name, as long as you don't mind having your head inside the aircraft for long enough to do that. And if you're trying to find a certain airfield just north of where I fly from, it might take a couple of attempts before you realise it's in the database as "Booker" and not "Wycombe".

After that, you'll be shown your track on the moving map, as well as a heading to fly. There's no wind correction though, you'll need to do that yourself. If the direct track takes you through any controlled or restricted airspace, it should be obvious from the moving map - although there are errors in the database, so best to check with your chart anyway. And it certainly won't show any TRAs.

If you can't fly direct, for whatever reason, it probably becomes far too complex to do in the air. You can certainly program in a multi-leg course with waypoints, but the chances of the waypoint you need being in the database are fairly slim, so you'd need to find the long/lat of your turning point, or else find it's radial and distance from a VOR, and program in a user way-point. Fine if you're doing it on the ground as part of your pre-flight, but I definitely wouldn't do it for a diversion.

The 430 has a very nice feature whereby once you've programmed in the destination airfield, you can pull up a list of all the frequencies for that airfield, and tune your radio into the frequency with a couple of button-presses. That might be enough that you don't need to pull out your Pooleys if it's a field you're familiar with, but if it's an unfamiliar field I'd still like to check the Pooleys for any local information.

I've said before on this forum that I'm not a huge fan of GPS. But, if I had to divert and I was in a GPS-fitted aircraft, I would certainly make good use of whatever features I could. At the very least, with the 430, this would be using the moving map to provide a visual clue as to where the airfield is. At best, I might use the Direct feature and the frequency list. I wouldn't rely purely on the GPS for the reasons listed above, but it can be a big help in reducing the workload at a very stressful time.

I'd imagine, having never used one in anger, that a GPS without moving map would be less use, but still helpful - it would provide a heading for you to fly, but without the visual clues it would take more brain-power, you'd certainly need to draw the course on a chart to check for controlled airspace, and if you can't fly direct it would be practically useless until after your last turning point. I'd guess.

Hope that helps!

FFF
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[andrewc]

A couple of other nice touches to add to FFF's message,

You can treat any waypoint as a VOR, so its very easy to
setup a user waypoint, say three miles east of EGXX, to
get yourself in the right position relative to a field.

You can also get the nearest airfields with frequencies
and runway lengths out of the database and go direct
to them.

The Garmin will attempt to fly a from/to track between points
and let you know how far off track you are in a VOR-like
fashion, alternatively you can deliberately go off track to
avoid some hazard and then go direct to your waypoint from
your current direction.

I personally work my flight out on the map at home, generate
the waypoints and a flight plan and then load them up into
the aircraft at runup time...you can also store flight plans
and invert them for coming back...

Okay, I'd better stop now, they are very nice pieces of kit,

-- Andrew

[FlyingForFun]

Yes, good point about the nearest airfield screen, I forgot about that. Very relevant, since Carlito's question was about diversions. But I'm not sure how many of the other features you mention would be useful in a diversion scenario, Andrew.

In fact, just reading through Carlito's post, he said:

You're diverted ... you get out your whizz-wheel, you account for wind and variation and off you go
I wouldn't use a whiz-wheel for an in-flight diversion! I generally have a rough direction of where the wind is from and what effect it will have on me. For a long cross-country I use a "wind star" - pre-calculate the drift angle for each of the eight main headings (N, S, E, W, NE, SE, NW, SW) and then use the nearest one if I need to divert. Not that this is at all relevant to the use of GPS though!

FFF
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[Lawyerboy]

I was going to say, actually - my instructor has never let me use the whizz wheel in flight. He always insists I work it all out in my head, and I have to say that as much as I curse him at the time I'm glad he does it. Never thought about a 'wind star' before; I rather like that.

[andrewc]

FFF, you're quite right, I was lost in a happy little world of thinking
how marvellous Garmin 430's are in general rather than
the specifics of diversions.

-- Andrew

[Volume]

I normally use the Garmin 95, old reliable techniology, no moving map, just a few buttons needed for all information.

I don´t want to rely on the GPS. I did it one time, and it was close to be the last, because it suddenly displayed the ´battery low´ warning, although it was connected to external power (at least there was a wire, but unfortunately no connection...) and quit within minutes while I was flying under severe weather conditions somewhere in northern france far away from the next airport ....
I just use the GOTO-Option, type in airport codes or the code of an airport on the same track as my waypoint and just follow the arrow to keep on track.
For the exact position on the track I use the map and the cockpit window, so I always have a back-up.
For the descend to my destination airport I also use the ´time to waypoint´ displayed simultanous with the track and direction information. (altitude over pattern divided by time to destination = vertical speed to fly).
Any other options ´modern´ GPS do offer, just make you relying on them, I don´t want to rely on computer and software based systems ! (Bad experience with these outstanding Micro$oft operating Systems ....)
It always is a good joke to think of a ´general protection fault´ message on your GPS until it really happens and you are over unknown terrain.

[RotorHorn]

Us fling-wingers don't have an appendage free to work a whizz-wheel in flight... :rolleyes:

Our VMC minima are lower than yours so I've not yet had to divert anywhere. (touch wood).

As someone else has already suggested - just select the 'nearest airport' function and pick one (on the Lowrance Airmap you just hit two buttons together and it automatically selects the nearest airport for you). Then all you have to do (aside from watching your airspaces on your map) is keep the heading it tells you that you need, the same as the track it says that your making.

I like the star idea. Not come across that before.

Anyway, if I needed to divert, I could just aim for a friendly farmer's field I suppose... :D

p.s. What IS the correct procedure for diverting? Do you just tell your destination Airfield? What about if you're no where near your destination?

[FlyingForFun]

RotorHorn asked:

What IS the correct procedure for diverting?
I've only had to do it for real once, which is once more than I'd like to have had to do it.

First lesson: there's no point taking a Pooleys with you if it's somewhere you can't reach it. In my case, I was in the front seat of a Super Cub, with no pax, and my flight case, including my Pooleys, was in the baggage compartment at the back. I didn't have any pax to help me reach anything. Since then, my flight case has always been somewhere where either I or my pax can reach it.

I think I was talking to a LARS station at the time. I informed them that I was going to divert to Cranfield due to IMC, could they please pass me the Cranfield frequency. Ok, that was the first hurdle sorted, I had a frequency.

I still didn't have any idea about runway layout, or any special circuit procedures, or any frequencies other than the initial frequency to contact them on. So, when told to pass my message, I told them I was a "Super Cub, White Waltham to Sywell, diverting to you due to IMC, unfamiliar with the field." I was expecting that the "unfamiliar with the field" bit would be enough that they'd go easy on me, and that's exactly what happened. They were quite happy to have me stay on the approach frequency all the way until I'd vacated the runway, and they let me do an overhead join even though standard procedures there don't allow them. Apart from that, everything is normal.

Do make sure that your destination field knows that you're diverting, even if you are familiar with the airfield (or if you've got your Pooleys in a more convenient location than mine was!) If nothing else, many airfields won't charge a landing fee for diversions! Don't be afraid to ask for any help you need. And apart from that, just treat it as normal.

If you're expected at your original destination, and you haven't informed them on the radio, I guess you could just call when you land, or pass the message via ATC and follow up with a call once you land. If you have a flight plan, there are rules about having to call the destination, which I can't remember off the top of my head, but common sense says that you should let them know asap.

FFF
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[Julian]

Dont forget you can also slave a GPS to a laptop or palm pilot arrangement and give yourself full moving map capabilities even with a cheapo GPS. GPS can be obtained for as little as £100 these days and even those are using 12 sats, an immense aid to situational awareness to be able to look at an actual map rather than a blank LCD screen with a couple of waypoint of a ref on it!