HelloAfter aligning the 3 IRS I made a mistake and switched IRS No 1 to OFF instead of NAV. Datas were lost and no longer available. No 2 and 3 are totally ok. Do I have to align No. 1 again or...What will be the consequences if I perform the fligt? Will there be any?ThanksTom

no LAND3 Ton

I found that out the hard way the other day. I was only messing around, - she nose dived into the ground just short of the runway at Gatwick. Thats the last time I fiddle with the IRS's :-lol

No Land 3. That's what I thought. Ok. I'll give her a try. Don't want to autoland anyway. best regardsTom

The captain's displays will also fail unless the INST source is switched to the C IRU.

You can't align an IRS in flight, so you would end up with a few interesting side effects :)In the RW, depending on system programming, the respective A/P may not engage in flight. E.g., if your Left IRS is OFF, your Left Autopilot won't engage.Some airplane systems may only use the Left IRS.. That is, it is hardwired to a particular system, and it won't matter what instrument sources you select, that particular system will fail. For example, on our older 744's, if the Left IRS fails, then the GPWS system will be affected.In the real world, you probably wouldn't take off without a serviceable Left IRS. In the sim world however, it can provide you with hours of interesting "what if" scenarios :)Cheers.Q>

Thanks Q and the othersI will depart tonight from KLAX to KMIA without the L IRS. Let's see what happens....REgardsTom