On Oct 27, 1:12 pm, Andrew Sarangan wrote:
On Oct 26, 5:07 pm, "S Green" wrote:





"Peter" wrote in message

.. .

"S Green" wrote

Its in the JAR instrument test standards and features within the learning
objectives for the ATPL Met exam.

Work it out. The difference is small on approach and greater at high
altitude but the examiner would be looking to see whether you have taken
account of the fact that temperature does make a difference.

In JAR land some say they are anal, others would take the view that they
do
it properly.

Is the pilot supposed to get the ATIS to get the surface temp and work
it out there and then?

What is the typical correction, for an airport at say 1000ft AMSL
which is ISA+10?

+40 feet. Being the height in thousands * 4 * ISA deviation

In this case 1 * 4 * +10

You are applying the calcualtion incorrectly. At a DH of 200ft, you
would be only (200/1000)*4*(+10) = 8ft in error, not 40ft.

The error of +40 ft would be correct only if you are at 1000 ABOVE the
airport, at which point the 40ft is insignificant.

At very large temperature shifts, (ISA-50) for example, the error
could become significant, which is why special procedures are
published for cold areas. For all other areas, you are really
splitting hairs.

If this is the only thing the examiner is worried about during a
checkride, I'd say candidate is doing a fine job.- Hide quoted text -

- Show quoted text -

Here is a table that lists altimeter errors due to nonstandard
temperatures:
http://www.faa.gov/airports_airtraff...7/aim0702.html