Cold temp corrections on LNAV appr
Joined: Jun 2004
Posts: 1,394
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From: Just Around The Corner
From Airbus “ Gettin grip with cold weather ops “ :
“ On approach, at least the following published altitudes must be increased in low OAT conditions:
• MSA,
• FAF altitude,
• Step-down altitude(s) and MDA(H) during a non-precision approach,
• OM altitude during an ILS approach,
• Waypoint crossing altitudes during a GPS approach flown with vertical navigation.
As it is not allowed to modify the altitude constraints of a non-precision approach, a minimum OAT to fly the approach with the «FINAL APPR» FMGC mode must be established.
For OAT lower than this minimum, selected vertical navigation must be used.”
“ On approach, at least the following published altitudes must be increased in low OAT conditions:
• MSA,
• FAF altitude,
• Step-down altitude(s) and MDA(H) during a non-precision approach,
• OM altitude during an ILS approach,
• Waypoint crossing altitudes during a GPS approach flown with vertical navigation.
As it is not allowed to modify the altitude constraints of a non-precision approach, a minimum OAT to fly the approach with the «FINAL APPR» FMGC mode must be established.
For OAT lower than this minimum, selected vertical navigation must be used.”
Joined: Dec 2012
Posts: 72
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From: N/A
If you choose to stay in an uncorrected altitude of 3000ft, than you have to start your descent later and apply the cold temperature correction on your FPA.
So -20 gives you 3,5*0,04= 14%. This means if you start your descent in DUS at 7.6 NM with an FPA of -3,4 you should be fine.
We only have to correct altitudes below the corrected MSA. So in this case all below 3192ft
So -20 gives you 3,5*0,04= 14%. This means if you start your descent in DUS at 7.6 NM with an FPA of -3,4 you should be fine.
We only have to correct altitudes below the corrected MSA. So in this case all below 3192ft
Joined: Mar 2007
Posts: 502
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From: Up North….
Does your company prevent you flying VNAV down to the LNAV minima? If it does then if you are at a non-temperature corrected platform, you will indeed have a shallower or later decent to the first temperature corrected checkpoint. If it is allowed then the aircraft will start the decent slightly later to maintain a constant angle. (Speaking from Boeing perspective anyway...)
