swiftski
Posts: 1837
Joined: Tue Dec 19, 2006 6:19 am

Cockpit Instruments; Do They Have A Cache?

Wed Sep 12, 2007 9:11 pm

When a computer, or mobile phone doesn't respond, often when it 'wakes up' or begins responsing again, anything entered will happen (i.e. a program will open or a call will be made) because the commands have been queued up.

Should cockpit instruments stop responding temporarily, would any already imputted commands be run once the instrument came back online, or would they have to be reentered?

If this system exists, what is it called?

Also, would it differ from a/c to a/c?
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Cockpit Instruments; Do They Have A Cache?

Thu Sep 13, 2007 1:43 am

Quoting Swiftski (Thread starter):

Should cockpit instruments stop responding temporarily, would any already imputted commands be run once the instrument came back online, or would they have to be reentered?

It's a bit of a corner case, since a cockpit instrument should never stop responding unless it has failed and, if it did, you'd probably quit using it even if it did come back to life.

Tom.
 
Ralgha
Posts: 1589
Joined: Tue Nov 09, 1999 6:20 pm

RE: Cockpit Instruments; Do They Have A Cache?

Thu Sep 13, 2007 2:03 am

Quoting Tdscanuck (Reply 1):
It's a bit of a corner case, since a cockpit instrument should never stop responding unless it has failed and, if it did, you'd probably quit using it even if it did come back to life.

That would be ideal, however there is no part of your statement that is true in the real world.

I personally have never used something in an airplane that "queued" commands when it temporarily stopped responding (not that it's all that common to begin with). Tere may very well be something out there that does behave like this, but I think it would be a bad operating model for that environment.
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KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Cockpit Instruments; Do They Have A Cache?

Thu Sep 13, 2007 3:08 am

Okay, over to GA land:

If, for example, the GPS wigs out, when it comes back online, it usually resumes the flight plan that it was on...I would hope it would be bright enough to pick up on a waypoint passage that may have occurred while the juice was off  Wink But that's kind of a worst-case analysis...
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
mandala499
Posts: 6460
Joined: Wed Aug 29, 2001 8:47 pm

RE: Cockpit Instruments; Do They Have A Cache?

Thu Sep 13, 2007 7:12 am

The instrument or the instrument display?
If there was a delay in the primary flight instrument display, then something's wrong... they're just there to display the data. If there's a lag, something is wrong with the signal generator (and possibly the flight guidance computers), so ideally, no, I wouldn't use it then... time to land on the standbys.

The only thing where this happens and it's OK, is with the Flight Management Computers... as it only sends outputs to the autopilot, but the manouvering is done by the autopilot.

If you're on a coupled GPS navigation, and the GPS failed, go to basic RNAV as far as you can while the GPS is off, once it's online again, adjust the flightplan by skipping the waypoints you've passed prior to reverting back to GPS.

An autoflight system should bring you back to Heading Hold Mode on a position failure...

Always remember to set up your RNAV for any potential FMC/IRS/GPS/GPIRS(/Omega/LORAN/INS) failure...

mandala499
When losing situational awareness, pray Cumulus Granitus isn't nearby !

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