Altitude window on the B737-800 NG
 

Can anyone tell me what it means when the altitude window flashes? In mid climb a few days ago it started to flash, it stopped a few thousand feet later on reselection of the altitude.
Looked in the manuals but cant find anything. A reference would be good too...Thanks all

Was it perchance flashing "50.000"...;)

Brgds,
Empty

I wish!!! lol :}

It was after selecting 27000, the previous had been 20000. It didnt flash to start with, started about 230.

Damn - now I thought I had an easy answer :p

Now I have to open the books :mad: - how low can one bow :}

C if I can find something - brgds
Empty

Wouldn't yr fleet office or training Captain have an idea?

Brgds

I had it happen on a -700 when I 'rolled' the MCP altitude to the exact altitude over a few thousand feet without having to 'fine tune' it for the last few hundred feet. I have heard( anecdotally) that this can happen but I'm not sure it's in black and white!

After 5 years on the 800 I have never seen this on the MCP. The FMA is a different story.... What brand MCP are you using? Collins, ect....

The Avro RJ control panel is based on the 737 (Honeywell) design; if the alt selector knob is spun fast towards the new value or the knob stops between detents, the system detects an invalid input and flashes the display. With a flashing display the knob should be turned to select / reselect the correct alt sel value as the alt capture may not work. A similar flashing display and / or large value displayed (50,000ft ?) indicates other failures.

I've had thesame thing happen to me twice (-700), when quickly winding the altitude window onto the required altitude in one go. It might be a feature to alert you to the fact that the number may 'look right' but was not selected 'with care.' This was the theory that the captain and myself came up with. But never found anything about it.

You can make the MCP ALT window flash at any selected altitude by not quite having the selector knob in the detent- even though you may have the desired alititude displayed in the window.

Give it a go- you need to have a steady hand! :D

Does it really matter !!

The flashing in this case is telling you something isn't right.
Get it looked at. There's no moving parts so it has to be a computer function either telling you it's broken or you selected something it can't do.
See the notes above about what it can't do...