PIOs MMIs APCs JCs
Consternation in Flight Test
Some research on the subject shows that we now have 2 more names emerging for PIOs
MMI = Man Machine Interface
APC = Aircraft Pilot Coupling
All meaning the same thing.
Guess someone needs to get a conference going with all the test pilots' schools to unscramble these acronyms/definitions.
Here is a 9 second JC which is certainly a pearler..
I heard an absolute pearler of a software PIO story from a Navy guy recently.
The diesel submarine has FBW engine controls. In this story the sub was trying to nose onto
the ramp at the sub base .
A particular technique to veteran sub drivers was to line up the sub and ramp and then 'burst' the throttle to
give a big momentum push.
Command would be "all ahead full,... pause,... all stop" in about 3 seconds.
Enter problem. The system started ramping up the engine to full power, but would not respond to the "all stop" command UNTIL
full power had been achieved. Engine spool up time was about 9 seconds by which time the sub was motoring at maritime granitous.
Next command was "JC,... all reverse full". Once the system achieved full power it processed the next command, all stop and started winding down by which time impact with the moorings/wharf ectetera had occurred.
The short period of calm was replaced with increasing chaos as the sub spooled up to full reverse power.
The command "all stop" occurred as the tail fins of the rapidly reversing sub split open the side of a tender vessel moored nearby.
With well executed silence our sub captain offered no more commands and removed himself from the loop and eventually both the engine and sub stopped with chaos all around. In this instance the PIO was primary the result of a FCS that processed commands sequentially without a feedback loop based on next commands
(I'm sure a software engineer or FTE would improve on this description).
On the subject of subs I also believe that something similar happened submerged when a command went in to the contril system to 'crash dive'. But it was close to the bottom and before the command could be aborted it had its nose deep in the bottom mud. How embarrassing.