Hi guys,

 

I have noticed this warning unable next altitude  suddenly started to appear on my FMC, what does it mean and how can I fix it?

 

 

I have noticed this warning unable next altitude suddenly started to appear on my FMC, what does it mean and how can I fix it?

Read FCOM2, page 11.31.21.

 

 

what does it mean and how can I fix it?

 

Using a little interpretation of the message itself: the FMC predicts that it will not be able to meet the next altitude constraint. If you're just seeing it, I'm guessing you've either started flying into a bunch of airports with tough altitude constraints, or you changed a habit such that your flying is causing this. As an example, you're forgetting to fully close your throttles prior to T/D.

 

 

Normally encountered on SIDS, a way around is to increase the take off thrust and modify the FMS acceleration height.

 

Jake Roberts

thanks guys, I have ever only encountered it with a SID

I have seen this message at EDDF when using the BIBTI3M SID off of 25C. The airport operational information advises to use a SID with the designator GOLF if unable to meet climb restrictions. So when setting up the FMC I just select BIBTI3G for the SID. No more messages. It’s a shame you don’t receive these messages until you are airborne and the climb restriction is staring you in the eye. 

I just saw this yesterday departing EGLL Rnw 09R CPT5J departure.  it was flagging  the initial climb constraint at 420AGL. The annunciation went away before rotation. There are just some of these advisory notices that you need to simply look at, evaluate and often safely ignore.  That departure requires a 4% climb gradient to 4000, something not coded into the SID but the initial constraint somehow triggers an advisory message. Whatever.