IRS position

[dikkeduif 11]

Hi, Just wondering how I put the coordinates for the IRS position into the FMC.I've moved the two irs align switches to nav. First it shows the on dc light, and then it goes to align. After a while it starts blinking so I suppose they are aligned. Now on the POS INIT page I need to fill in the IRS POS, so I go to page 2 but it doesn't show me any coordinates for IRS L or IRS R, I can only choose the coordinates for GPS L and GPS R.Is this normal? Or am I forgetting something? D

[Jigsaw 8]

At the top of the page there should be a "last position" entry. Click on the line key of that entry. That will copy the coordinates to the scratchpad line. Then just click on the IRS position line key to fill in the info from the scratchpad.

[henri5 16]

sometimes you have to put the IRS knob to off in order to erase the wrong coordinates on the FMC POS page. At least that worked for me when I spent a half hour trying to align the IRS. Henri

[g_precentralis 191]

You can use GPS coordinates too, or you can use coordinates for your stand which you can find in charts for that airport, or you can enter airport ICAO code and stand number in L2 and L3 on the first pos init page, then pick up correct cordinate and transfer it to R4. Lj. Prodanovic

[DylanC 158]

Once you do that, don't forget to move the IRS selector switches to the "NAV" position to complete the alignment.

[ajacied551 1]

Hi Donald The IRS coordinates on page 2 of the POS INT page stay blank until you enter the coordinates on the page 1 on LSK 4R to the SET IRS POS, you use the GPS coordinates to set the IRS position. When no IRS position is entered in due time the ALIGN light flashes unitl the IRS position is entered. After the IRS alignment is done only than the IRS coordinates will show on page 2 of the POS INIT page.

[Meese 5]

Guessing you're not entering the coordinates. Go to POS-page, go to page two, confirm that GPS L and R show the same coordinates, then choose (click on) any one of them. This should make the coordinates show up in the scratchpad (bottom left corner of CDU display). Go back to page 1 (prev page), then click on the button by the empty field (empty boxes). Those boxes will show a couple of seconds after you set the IRS-switches in aft ovhd to "allign" or "nav", so if they don't show, wait a bit.

[andysim 0]

i put them to NAV right from the off. Dont wait on the Align setting just got from OFF to NAV.

[henri5 16]

Guessing you're not entering the coordinates. Go to POS-page, go to page two, confirm that GPS L and R show the same coordinates, then choose (click on) any one of them. This should make the coordinates show up in the scratchpad (bottom left corner of CDU display). Go back to page 1 (prev page), then click on the button by the empty field (empty boxes). Those boxes will show a couple of seconds after you set the IRS-switches in aft ovhd to "allign" or "nav", so if they don't show, wait a bit.

In my experience this will not work if there are already incorrect coordinates in the "normally blank" line for the POS. In that case, I succeded in copying the GPS coordinates only after I turned the IRS knobs to "off" then back to "nav". I did not think of using the "delete" or "erase" command to get rid of the incorrect coordinates, but that might work. Henri

[ajacied551 1]

In my experience this will not work if there are already incorrect coordinates in the "normally blank" line for the POS. In that case, I succeded in copying the GPS coordinates only after I turned the IRS knobs to "off" then back to "nav". I did not think of using the "delete" or "erase" command to get rid of the incorrect coordinates, but that might work. Henri

You can always override the IRS coordinates you entered when still in ALIGN mode but you can not delete or erase the IRS coordinates you entered. When you entered the wrong IRS coordinates that is not near your current position the IRS system gives you a message to re-enter the IRS position. But that is on the real A/C.

[dikkeduif 11]

Thanks guys. :)