Does anyone know if standby instruments (specifically the standby altimeter) is less precise than the main instrument? If this is so would the 300 ft altitude error be typical? I need this information for a heated discussion on another (no-English) discussion forum. Thanks.Michael J.WinXP-Home SP2,AMD64 3500+,Abit AV8,Radeon X800Pro,36GB Raptor,1GB PC3200,Audigy 2http://www.precisionmanuals.com/images/forum/747400.jpg

For RVSM regs all 3 altimeters - Captain, FO and Standby must be within a certain tolerance of each other. Not sure what this tolerance is.

My 767 Flying Manual quotes the following."Altimeter (main and standby) tolerance on ground check is +/- 50ft of each other.All altimeters should indicate a sensible value dependent upon the aircraft position relative to the airfield reference point."No figures are quoted when airborne but I'm sure I have seen +/- 200 between main altimeters and standby altimeter.Both main altimeters have vibrators to ensure the needle movement is smooth and and the indication doesn't stick. There is some lag in the standby.Hope this helps.Chris

The values, airborne, vary with altitude. I seem to recall that 300' is right on the tolerance limit at normal cruise altitudes.Cheers.Ian.

In cruise, in the FL300-390 range, in the real airplane (767-300) the center altimeter reads around 400 feet higher than Capt or FO. On aircraft having the integrated standby instrument (glass guage with ADI, Heading, airspeed and altitude on one small screen) the altitude comes from one of the ADC's and is spot on with the main altimeters.Tony Vallillo