Present Position Entry on IRS DISPLAY (partially) not working

[xplana]

hi folks,

i just tried to enter the pressent position on the IRS DISPLAY. I managed to enter the current Latitude, but

> its not possible to enter a Longtitude. I just folllowed the steps from the manual:

 

 

[JRBarrett]

Be sure that the degrees portion of the longitude contains 3 digits. In other words, if your longitude is 75 degrees, 14.5 minutes west, you would enter in as W07514.5 or if the longitude was 5 degrees, 14.5 minutes, you would enter it as W00514.5

Likewise, the latitude degrees entry needs to be two digits, with a leading zero if the current latitude is less than 10 degrees.

Not sure if this is the cause of your problem, but it is one common user error that would prevent the IRS from accepting the PPOS.

Although it is possible to enter your present position directly into the IRS control unit in the overhead panel, the more typical procedure would be to key it in using the FMS CDU.

[xplana]

Thanks JRBarrett!
Something is weird (it might be me), but today it worked just as it was supposed to do - so probably me :-(

[Litjan]

Also be aware of the fact that the position must be "pretty much correct". Otherwise it will not be taken by the IRS - this is a modeling limitation - otherwise we´d have to go to the length of keeping track of a "false" position with everything that entails (MANY ramifications...) While this may look like a shortcoming, it really isn´t much of one. The real IRS will also reject false positions (comparing to last known position, comparing latitude to current turn-rate of earth) and will also correct a wrong IRS position very soon through GPS (or DME) updates...

Jan

 

[xplana]

thanks for "Aufklärung", Jan