Is it usual to have differences between the altitude readout on the PFD and the altitude indicated on the standby altimeter? With a QNH of 29.92, they both start out indicating the same readout, but as the altitude increases, the two no longer indicate the same readings. At FL240, the difference is about 300ft and increasing. The readings start to slowly diverge at about FL100.Michael Hesse

Yes, variations are perfectly normal for all Boeings. The Standby Indicator may have a different source of air data and does not have all the corrections the PFD displays have. The same applies to airspeed. Tolerances are usually given in Maintenance and Ops Manuals. The Stby Altimeter usually gives a higher altitude than the main instruments, I'm told.Regards.Ian.

Ian thanks a bunch for your reply. I guessed this to be the case for two separate, independent, altitude systems on a real plane. I was just surprised to see a difference in FS2002 that (to my very limited knowledge) only simulates a single altitude system and both gauges are driven off it. If these types of variations are normal in a real Boeing then I

"I was just surprised to see a difference in FS2002 that (to my very limited knowledge) only simulates a single altitude system and both gauges are driven off it."Same here. It would be nice to know if the variations are intentional :-)"If these types of variations are normal in a real Boeing then I