View Full Version : Jeppesen plates and below ISA corrections.
320DRIVER
25th Dec 2001, 15:38
Do standard (non-customised) Jeppesen approach plates cater for low temperatures (below ISA)? i.e. do you have a lower limit temperature until when theycan be used in order to assure terrain clearance as per PAN-OPS or does the pilot ALWAYS have to correct the charted altitudes when temperature is below ISA?
Thanks for any info.
bizjet pilot
25th Dec 2001, 15:58
The short answer is: "no." Below ISA temps are NOT accounted for in the terrain clearance implied by given QNH-flown altitudes.
Yes, you do have to make your own corrections based on the table to which you allude.
Many exhaustive posts this topic in the PPRUNE archives by-the-way.
An excellent point to raise as the temps plunge. Merry Xmas, if applicable.
[ 25 December 2001: Message edited by: bizjet pilot ]</p>
320DRIVER
25th Dec 2001, 16:56
Applies indeed my friend... as I am in between portions of roast turkey and roast potatoes!... :-)
I raised the question because I was reading somewhere (I think it was a paper available on Bluecoat) that some new RNAV charts are now certified to give the required clearance to, say, a temperature of 15 below ISA (based on the characteristics/location of the airport) and only after that are pilots required to apply corrections.
Anyways, a Merry Christmas and a Happy and Prosperous New Year to you.
A and C
25th Dec 2001, 18:15
You will find an altitude correction table in the terminal section page 13.
320-
I agree with bizjet. In a nutshell, if you "read" the minimum altitude (as from an approach chart or a map), you should/must be aware of the error and apply a correction. If you "hear" an altitude (as assigned by ATC) then you should fly it as assigned. Different countries have different methods of correcting assigned altitudes for cold weather, so if in doubt, ask.
On the RNAV approaches, the ones with which I am familiar say "Not Authorized below -15C." In other words, I think you have it backwards. The corrections should be made on those approaches until it drops below -15C, at which point it's NA.