Hi all! I recently noticed a prompt after entering the IRS position on startup that says "set IRS heading" on the FMC. I've never noticed that before, does anybody know what it is and if has always been there or just appears at certain times.

Is it the current heading that I have to imput?

Cheers all, Matteo Capocefalo, MED1473

The IRS mode switchs are set to ATT mode instead of NAV mode. When in ATT (attitude) mode you need enter the current heading of the airplane. The current heading is readable from the Standby Magnetic Compass. Underneath the FWD overhead panel between the two cockpit windows.