In the thread about
BA1 getting 'lost' in Shannon, this comment by
Snafu_again caught my attention:
Originally Posted by
Snafu_again
How is the data uploaded to the FMC ? .... would you believe from a 3.5 inch floppy disk ! (and they cause no end of problems (more the loading machines rather than the disks)). Why not USB or Memory Cards ? Because of the cost. Modifying the aircraft, certification etc.
Aside from being mildly amusing (another interesting recent use for 3.5" floppy disks includes Norway's doctors, which
ended in 2015), this got me thinking about the Flight Management Computers in use on airliners. I did have a quick look to see whether this had been covered before, but didn't find anything, so…
1) What kind of computation does an FMC do? Do these tasks vary significantly between different (sub)-types of aircraft, families of aircraft, or even individual airlines? I assume there are lots of 'keeping the plane running' tasks that are involved – e.g. balancing fuel between tanks, handling conflicts between information from redundant sets of equipment, etc.
2) What kind of hardware and software do FMCs run? Presumably they need to be specially hardened and certified, but how 'current' are they, given the long lead time between designing and certifying the plane, it entering service, and the lifetime of the airframe itself?
3) How involved is BA/BA engineering in the specification of such FMCs, or is it 'standard' from the aircraft manufacturer (linked to Q1 above).