GPS co-ordinates in an emergency: any useful?

[Deeday]

Hi all,

I've recently got my PPL and just bought my first GPS unit, so I was wondering: in a Mayday call, would it be any better to declare the current position using GPS co-ordinates, as opposed to the standard distance-from-landmark position report?
I could think of two reasons why that could be preferable:
I suppose it's a lot easier for the pilot, in an emergency, to just glance at the GPS and read out the co-ords, rather than working out the current position relative to some meaningful landmark nearby.
It can be a lot more accurate than a vague "5 miles South of XYZ".On the other hand, ambiguity may arise with regard to the format of the GPS co-ordinates used in the call (degrees-minutes-seconds or degrees-fraction etc.) My question is: what do the guys who actually receive the call think?
I'm sure the subject has already come up somewhere, but I couldn't find any thread on the topic.

Cheers.

[HEATHROW DIRECTOR]

Almost certainly, the controller you would be talking to would not have access to a map and his radar would not show co-ordinates. If you gave your position as "XX miles southwest of YY" he would look at the radar and probably see you immediately. Also, what GPS co-ords would you use? Lat and Long in deg, min, sec? Lat and Long in WGS84? UK OS grid reference? It would be far too time-consuming for a busy controller to use them.

[fisbangwollop]

The best thing you can do if you have the time is give ATC as much info as possible but if you are transponding change your squawk to 7700.....this will then at the very least alert D and D to the fact that an aircraft has a problem and even if no ATC unit is talking to you tracing action can then be initiated....the great thing about the 7700 squawk is that it will remain on the radar screen till manually cancelled....so if you were going down fast and descending quickly below radar cover the SOS label will remain on the radar so an accurate position of the aircraft in distress can be worked out!
:cool:

[eastern wiseguy]

Agree with HD to a certain extent. If you are allocated a specific squawk or give me a ROUGH position I can place the rolling ball over your return and that will automatically give me a LAT/LONG.Useful for sending the emergency services and in that case better than a vague 3 miles south of Ballgobackwards....of course they could just look for the smoke if there was any!!:}

[HEATHROW DIRECTOR]

But do all ATC units have the rolling ball-lat-long readout bit? None where I ever worked had it but it sure sounds like a very excellent facility.

[eastern wiseguy]

Well we have had ours since 2001. It is the same kit at Cardiff....NATS units. Can't speak for elsewhere though. Anyone?

[reportyourlevel]

We (non-NATS) have Flight Refuelling radar processors which give a lat and long from the ERBM position.

[Deeday]

Thanks for the replies. I agree that, if I'm already on somebody's radar, a traditional position report would make more sense (or even no report at all, in theory, under SSR and squawking 7700).
Outside radar coverage though, I think GPS co-ords would provide much valuable information to the search & rescue guys, provided they are communicated without ambiguity (minutes/seconds vs. decimal etc.) By the way, I didn't know about the different reference frames; I've noticed that my Garmin defaults to WGS84; are there other frames in use in the GA/civil aviation world?

On a slightly drifting note: say that I am in distress in a remote area and only manage to read out my GPS co-ordinates once, at the speed of sound, i.e. the poor guy at the other end doesn't manage to write them down. How easy is it for you guys to play back the tapes on which, I'm assuming, the transmission has been recorded? Can you do it at the touch of a button or is it something you normally leave to the air crash investigators, when they ask for it? Just out of curiosity...

[pumuckl]

We certainly have the Lat & Long rolling ball at our Non-Nats unit (it seems the same set up as reportyourlevel - Flight Refuelling radar processors). I would have thought most radar units would have this, surely? Definitely very handy when advising D&D of a position.

That said, if you are transponder equipped, we would hopefully be able to identify you very quickly without the need for you to go into the lengthy readout of your lat & long from your GPS unit.

If you are not, then hopefully you would have been speaking to someone and hopefully we should have a general idea of your position at the very least. If you quickly read out the lat & long, then chances are the controller would have been able to jot down the details, always a pen in hand.

However, as to quickly pulling the tapes, it can be done, but not at the touch of a button by the controller - it would involve a request to the Tels guys/girls in the basement who will be able to pull the tapes and replay them, but there would be a few minutes delay (at best) in organising this generally. So yes, it can be done in a hurry, however, generally speaking the tapes would be pulled after a mayday incident as a matter of course as part of the reporting procedure by the controller to the CAA who may or may not request to listen to them, depending on the incident.

Cheers
p. :ok:

[HEATHROW DIRECTOR]

<<I would have thought most radar units would have this, surely? Definitely very handy when advising D&D of a position.>>

I've never seen it in a lifetime in ATC (unless my knackered memory is playing up!). Is it available on the NATS TC and AC radars? On the occasions when I needed to liaise with D&D I used simple information like a radar handover, e.g. "3 miles south of Woodley"

[ATCO1962]

We're fortunate enough where I work in the Middle East to have both a lat/long cursor readout on our screens and an instant replay facility for any land line and air/ground comms. You can't believe how handy that is in an area of the world where English is not the primary language spoken by most of our customers and comms can be scratchy a lot of the time. I'm surprised that major units everywhere don't have instant replay. We use it a lot.

[TC_LTN]

We have had the facility in TC for some time now and its use is being reinforced during TRUCE, I understand.

[5milesbaby]

Since moving to Swanwick we are able to put the mouse cursor anywhere on the radar and click to bring up a lat/long box, it works providing a TDB isn't in the way........

Never used it other than to play with it......

[Talla Radar]

...and when Prestwick Centre goes operational later this year, we will also have access to LAT/LONG on our radar displays.

[Standard Noise]

Lat & Long is available at Brizzel, has been for donkeys years but if you're south of us below certain levels, your SSR code could be masked by the Mendips so if you give us a correct Lat & Long, it could help pinpoint you.

Mind you, we found a C172 years back (when I was at Coventry) using the ERBM and an OS map with range rings drawn on it, when it went down north west of Stratford. We were close, pinpointed it to a field across the road. Warwickshire RFFS wouldn't accept the Lat & Long though, insisted on an address!:ugh: So we told them the name of the two closest farms and sent them on their way.

[BDiONU]

However, as to quickly pulling the tapes, it can be done, but not at the touch of a button by the controller
D&D can do it at the touch of a button for 121.5 and 243.0

BD

[Quintilian]

Lat/Long also available here in Norway.

We can press a shortcut on the text-input-display and then just write the lat/long to have it instantly pop up on the monitor attached to a vector you can fasten to another point or to an aircraft.

[HEATHROW DIRECTOR]

I can think of one very good use for it... We used to play a game when it was quiet in TC. Set up the whole UK coastline on the videomap and offset to anywhere along it. Now change the range to about 5nm so you have just a short stretch of coast showing. Game is to get your "opponent" to say where it is. If he now only has to put the rolling ball on it for the lat-long to show that would definitely be cheating!

[LEGAL TENDER]

Sounds like hours of exciting fun HD ;)

[BaldEd]

In NZ we have lat and long (WGS84) available on the radar displays. Almost instant replay of voice available on each controller position. "Say again" facility (last message received) is a 1 touch screen button press. Replay of all previous rec/trans/phone messages selectable by time or FF by touch screen buttons.

[HEATHROW DIRECTOR]

BaldEd.... You're light years ahead of us.

Doesn't seem like 2 years since we were dining with you!!

Bren & Ruth