A320 Opt Alt Change When OAT sudden Increase

[Neupielot]

Anyone had this before? U flying along and enters cloud. The OAT suddenly increase ( prolly in CBs ? ) and the Opt Alt Changed. I'm not sure if the Max FL changed as well ( must have i think) .
Do we need to request descent now to below the MAx alt shown on the FMGC assuming you have no idea how long you gonna be in this area of higher than normal OAT?
If u stay at the level, do u lose any info on the MCDU? fuel figures, eta , etc?
Also, will the VLS increase ( assuming you in this for extended period of time)?

It didn't happen to me so i'm trying to find out the answers before i get into this situation.
Thanks.:)

[rudderrudderrat]

Hi Neupielot,

You'll notice a change in the ISA deviation as you fly across the frontal boundary between cold and warm sectors and often as you cross the jet stream. These areas are well forecast.

If you think you are going to fly into a warmer sector, then don't climb too close to Maximum Alt. All the data from the FMGC will still be there, although it may assume you'll descend again shortly to Maximum Alt (if you've inadvertantly exceeded it).

I don't recommend trying to outclimb the tops of CBs, you are better off using your WX radar to fly around them at Optimum Alt or even slightly lower to give yourself a bigger margin either side of your turbulence penetration speed.

[potkettleblack]

Also have a look at the environmental envelope in FCOM 3.01.20. When we first get our flight plans in ops we will check what the forecast ISA deviation is for the route. If its particularly cold then we will stay a bit lower.

[Timothy Claypole]

I've experienced this once when climbing into a warmer air mass. The first indication was the rapidly rising barbers pole on the PFD, and a quick cross check of the FMGC revealed the max alt had dropped by a couple of thousand feet! A slow climb in V/S then ensued until we coould get clearance for a return to a lower level. I learned about flying from that.

[Neupielot]

Thanks for all the info guys. Gotta love pprune.:)

[Max Angle]

as you fly across the frontal boundary between cold and warm sectors

Which is one good reason why fronts should still be shown on sig. wx charts. I would love to know what ivory tower official decided they should be removed.