Quick UTM Coord sample problem (omitted zeros)

[effte]

Concerning the streepoint's elevation... do you mean its elevation above MSL, or above ground (probalby the former, but maybe the TDU has the ground elevation above MSL stored already and "knows" the ground's elevation automatically)?

 

Heights are a rather more complex subject than most assume.

 

UTM and MGRS reside in the WGS84 (World Geodetic System) reference system. WGS84 defines the coordinates for positions across the surface of the earth. It also defines the surface of the earth as an ellipsoid, the WGS84 ellipsoid. This ellipsoid is a rough approximation of the actual surface of the earth.

 

Three-dimensional coordinates under WGS84 include a height above this ellipsoid - ellipsoid height.

 

(This is a height and not an altitude, so no need for reference pressures (QNH/QFE/QNE).)

 

This height is not the same as the height above mean sea level.

 

There's another earth model defined, the geoid, which describes the shape the earth would have if it was completely covered with water - a theoretical sea level surface, covering land and oceans alike. This is a rather uneven shape. Variations in the distribution of the mass of the earth will cause local variations in gravity. If you e g have a large ore body in the crust of the earth, or a mountain, the mass concentration will cause a local increase in gravity which pulls water in, thus raising the surface of the geoid. The neat thing about the geoid is that local gravity is always perpendicular to the geoid surface.

 

For every point on the planet, there is a geoid undulation, which is the height of the geoid (or the theoretical sea level surface at that point) above the reference ellipsoid. To convert the height above the reference ellipsoid, e g as reported by your GPS operating in WGS84, to a height MSL you need to subtract the geoid undulation.

 

What we enter should be the ellipsoid height - the height which a GPS would report. The aircraft would then need a geoid model to convert this to a height MSL, if this is desired for some reason. As the aircraft lives in WGS84 already, it really only needs the ellipsoid height for the systems to do their job.

 

Cheers,

Fred

[CharlieMike24]

Bump.....

 

Having this bug still, with 5 digit UTM.

 

Anyone know of plans to fix this?

[711Hancer]

you can either use the first three information JTAC gives you lines (1,2 and 3) (i.e.: ADDLER 334/20) and enter these data to your offset page on the cdu as a new waypoint.

 

or

 

generally if it gies you 5 digits, put a 0 after the third digit or the last digit while entering the coordinates.

 

or

 

use your tad and hook the red triangle

, the data markpoint JTAC sent you and set it as your waypoint.

 

this is still a bug and please do not necro threads :)

Edited October 1, 2011 by 711Hancer

[Evil.Bonsai]

you can either use the first three information JTAC gives you lines (1,2 and 3) (i.e.: ADDLER 334/20) and enter these data to your offset page on the cdu as a new waypoint.

 

or

 

generally if it gies you 5 digits, put a 0 after the third digit or the last digit while entering the coordinates.

 

or

 

use your tad and hook the red triangle

, the data markpoint JTAC sent you and set it as your waypoint.

 

this is still a bug and please do not necro threads :)

 

Better that than make a new one. I was having this same issue yesterday. Couldn't figure it out at all. Co-ords were gh36497. Then, I think, I had a 'random' fail with cdu: I couldn't input ANY characters except for wp name. None of the other entries would work (elev, utm, coords). I ended up quitting, turned off 'random failures', searched for this issue then went back in to re-play mission. Got it THAT time. :\

[Kula66]

I had this happen to me ... I'm west of Batumi, getting co-ords for a target just east and when entering the data into the CDU I get a mark out in the sea, next time I'll try putting the zero after the first 3 digits!

 

Could do with a decent fix really!

[WildBillKelsoe]

input as dictated..

[effte]

generally if it gies you 5 digits, put a 0 after the third digit or the last digit while entering the coordinates.

 

No! It omits leading zeroes from either the easting or the northing. Not trailing zeroes.

Edited October 2, 2011 by effte

[711Hancer]

according to my general experience with this situation;

 

it works when you enter a "0" after the third digit.

 

yesterday JTAC gave me a coordinate having 4 digits, now thats rare.

[Kula66]

Just to confirm, putting the extra zero in after the 3rd given digit worked ... :)

[Evil.Bonsai]

After a short mission I ran yesterday, at this point I'm thinking a string of random numbers might be just as good. I can post a track in a day or so, but the location jtac gave me wasn't even close. It was at least 3kI off. After 'mark on deck', even with f7 I couldn't find the smoke.

[kylania]

Sounds like you ran into the 37T vs 38T thing maybe? Remember the mission it was in or what the coords were vs the airfield you took off from?

[cichlidfan]

Just to confirm, putting the extra zero in after the 3rd given digit worked ... :)

 

 

NOTE: Putting the zero after the third digit in a five digit string means that you are inserting a leading zero in the second number.:doh:

[CharlieMike24]

NOTE: Putting the zero after the third digit in a five digit string means that you are inserting a leading zero in the second number.:doh:

 

Yes. It seems to be the leading zeros that are omitted rather than trailing ones.

[effte]

Yes. It seems to be the leading zeros that are omitted rather than trailing ones.

 

No kidding... :doh:

 

First link in first post in this thread:

 

DCS caveats

 

DCS:A-10C seems to have a bug in the implementation of how MGRS coordinates are given to the player. Apparently, leading zeroes are dropped. I e AB023467 is given as AB23467. This is an incorrect MGRS coordinate, as the number of figures is always to be an even number (the same number of figures for the easting and the northing). If you get a coordinate with an odd number of figures, something is amiss and you should add a leading zero.

 

If there are two leading zeroes, it will probably mean both are dropped, ie AB002467 becomes AB2467. Apart from the coordinate possibly having a lower precision than you would expect, there is no way for you to know that this coordinate is in error – apart from it being way outside of your assigned area.

 

There is a possibility that it will also drop zeroes from the northings, ie AB234012 will be given as AB23412. This is to the best of my knowledge unconfirmed, but if you get coordinates which are simply way out into nowhere, please jot them down along with other coordinates given and report.

Edited October 3, 2011 by effte

[kylania]

yesterday JTAC gave me a coordinate having 4 digits, now thats rare.

 

A 4 digit grid is the same as "There's targets over yonder! *points*" :joystick:

[effte]

A 4 digit grid is the same as "There's targets over yonder! *points*" :joystick:

 

Kilometer precision. Perhaps not desirable, but for a reasonably visible target quite usable.

 

(a) Target coordinates (preplanned and immediate) and associated TLE

only need to be of sufficient fidelity to create the desired effects on target through

efficient battle tracking and effective fire support integration. The level of precision and

accuracy required for the target coordinate and TLE will be tactical scenario dependent.

Time to kill should not be sacrificed in order to generate more coordinate precision and/or accuracy than is required for successful target prosecution; if the current

coordinates, TLE, CAS asset, ordnance, mark plan will create the desired effects on

target.

 

But then again.

 

First link in first post in this thread:

 

DCS caveats

 

...

 

If there are two leading zeroes, it will probably mean both are dropped, ie AB002467 becomes AB2467. Apart from the coordinate possibly having a lower precision than you would expect, there is no way for you to know that this coordinate is in error – apart from it being way outside of your assigned area.

 

AB024067 would also generate a four-digit coordinate, AB2467 again. You have no way of knowing if it was indeed meant as aa four digit coordinate or if it was AB002467, AB024067 or AB246007.

[711Hancer]

maybe we should kill the JTAC instead

[Kula66]

A 4 digit grid is the same as "There's targets over yonder! *points*" :joystick:

 

Not really true ... if we are saying that the JTAC code is in error and dropping leading zeros, then 'he' is still giving you a 6 figure ref, with associated accuracy, just reading it as a 4.