Classics FMC

[Harry Cane]

Hi guys

Have a question regarding classics 73s.
What Air Data Computer, under normal conditions, feeds speed information to the FMC (single Fmc Configuration).

Thanks.
H.C

[CaptainSandL]

Both!

The FMC gets speed input from both ADCs and both IRSs. However the primary/preferred (variation in Boeing terminology) sources are the left ADC & IRS.

S&L

[Harry Cane]

Harry Cane

Thanks for your answer Capt. Sandler, and here’s another related question.

How the Fmc will respond in case of slight difference in speed information between ADC 1 and ADC 2 due to a partially clogged pitot system affecting the preferred ADC (ADC 1).