A320...Max Ceiling FL390 Vs Max Rec FL398 ?
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Joined: Mar 2006
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From: kuwait
A320...Max Ceiling FL390 Vs Max Rec FL398 ?
Hello...
i always wander....why is it showing in the MCDU the max rec is FL398 although why can't climb more than FL390 as is it a limit.
why we have this 800 feet more ?
my personal thinking is ...this 800 feet is to allow for a TCAS RA (Climb) at FL390 ?...may be ?
what do you think ?
i always wander....why is it showing in the MCDU the max rec is FL398 although why can't climb more than FL390 as is it a limit.
why we have this 800 feet more ?
my personal thinking is ...this 800 feet is to allow for a TCAS RA (Climb) at FL390 ?...may be ?
what do you think ?
Joined: Mar 2000
Posts: 1,337
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From: Sunrise Senior Living
On the new-ish 319s, it's FCOM 4.3.25 P107 which says:
REC MAX This field displays the recommended maximum altitude (in magenta), that is computed based on the current gross weight and temperature. It provides the aircraft with a 0.3 g buffet margin, a minimum rate of climb at MAX CL thrust, and level flight at MAX CRZ thrust. This field is limited to FL 398.
If one engine is out, this field displays the recommended maximum engine-out altitude, that is computed based on the long-range cruise speed and assuming that anti-ice is off.
My understanding is that the increase was made from FL391 to FL398 to allow those that still cruise in metres (Aeroflot which bought the 319) to use the 12000M cruise level.
Cheers,
mcdhu
REC MAX This field displays the recommended maximum altitude (in magenta), that is computed based on the current gross weight and temperature. It provides the aircraft with a 0.3 g buffet margin, a minimum rate of climb at MAX CL thrust, and level flight at MAX CRZ thrust. This field is limited to FL 398.
If one engine is out, this field displays the recommended maximum engine-out altitude, that is computed based on the long-range cruise speed and assuming that anti-ice is off.
My understanding is that the increase was made from FL391 to FL398 to allow those that still cruise in metres (Aeroflot which bought the 319) to use the 12000M cruise level.
Cheers,
mcdhu
Only half a speed-brake
Joined: Apr 2003
Posts: 4,459
Likes: 136
From: Commuting not home
kuwait340: So, which one was it? Old A320 with new software that cannot see the true ceiling, a new A320 with cost-saving option re-certified to 390 only, or perhaps a true S12100m capable aircraft, but your company does not need to use it?
FD (the un-real)
FD (the un-real)
Only half a speed-brake
Joined: Apr 2003
Posts: 4,459
Likes: 136
From: Commuting not home
I did not expect anything less
So, perhaps you are not in fact limited to FL390, just have no airspace to use anything above it up to the aircraft's true limit. FCOM 3.01.20 p2 Limitations - Environmental Envelope refers. 
So, perhaps you are not in fact limited to FL390, just have no airspace to use anything above it up to the aircraft's true limit. FCOM 3.01.20 p2 Limitations - Environmental Envelope refers.
