What is DATM on ODU option 4?

[ASW]

I looked for it in three instructions (Pocket, BY CHUCK and Harrier Manual CH 1-15) but I didn't find it anywhere.

[AlphaJuliet]

It is to input the local magnetic variation

[Shiroka]

2 hours ago, AlphaJuliet said:

It is to input the local magnetic variation

Not quite - it’s to change the coordinate geodesic Datum (WGS84, NAD27 etc). That will affect the local Mag Var but also everything else - coordinates, true north etc. Not sure different Datums are modeled in DCS (I guess not) but when you push this it should display the default datum, which is 47 (WGS84) and allow you to enter a new 2 digit number from 01 to 47. There is a table mapping numbers to Datums in the TACMAN (Vol 1, fig 1-169, pgs 1-256 and 1-257).

[AlphaJuliet]

Interesting, no mention is made to that in the NFM version that I have, it just says to cycle the DATM to input the MAGVAR

[Shiroka]

16 hours ago, AlphaJuliet said:

Interesting, no mention is made to that in the NFM version that I have, it just says to cycle the DATM to input the MAGVAR

Yeah I looked for it in the NFM too but couldn’t find it. Looks like it’s in the TACMAN instead (at least the 2008 version)

[gmangnall]

From TAC-000   1.12.6.4.5 Waypoint Datum. Datum selections can be made through the ODU/UFC (option 4). Datums are identified by numbers 1 through 47. See Figure 1-169. The datum name associated with each number should be listed by the pilot on an admin or brief card. Selecting a new datum changes the latitude, longitude, and UTM of the waypoint/offset, but does not move the waypoint/offset symbol on the display. Datum transformations take place in the MAGR in approximately 2 to 3 seconds. While the MAGR calculates the new coordinates, the waypoint/ offset symbol disappears. The waypoint/offset reappears when calculations are complete.