Trying to work out altitudes you would expect to see at airfields like LAX where you have to capture the glide from above in ISA plus 15 temps.
i i have a calculator for cold temps which says if I were @ 5000’ -10 degrees C then my actual alt would be 4500’
What would be the actual altitude at 25 degrees C @ 5,000’?
(the relationship doesn’t seem to be linear as the temperature gets colder...so I guess it isn’t 10% / 10 degrees when the temperature gets warmer)?
eckhard
18th Mar 2019, 00:30
A rough approximation for altimeter temperature error is 4ft error per degree C dev from ISA per 1000ft above the ‘source’ (airfield). This assumes a constant deviation from ISA in the air mass beneath the aircraft, which is difficult to establish.
For your example of LAX 24R and ISA+15, the following would apply:
Waypoint.....I-OSS....Charted.....Temp.....True Alt.....True alt of
......................DME.....Min Alt.......Error........................3 Deg GS
SKOLL..........37.3.......10,000.........600.......10,600... .....11,473
DECOR........33.7.........9,000.........540.........9,540... .....10,321
BREEA.........30.1.........8,000.........480.........8,480.. .......9,169
PALAC..........26.5........7,000..........420........7,420.. ........8,017
LIVVN...........22.6........6,000..........360........6,360. .........6,769
BROUK.........19.4.......5,000...........300........5,300... .......5,745
MERCE.........16.2........4,000..........240........4,240... ......4,721
JETSA...........8.3..........2,200.........132.........2,332 .........2,193
So, on the face of it, the ILS glideslope would be above the minimum altitudes until JETSA. What makes you think you will have to intercept it from above?
I have flown this approach several times, although not recently, and I can’t remember it being difficult from that point of view.
FlightDetent
18th Mar 2019, 00:36
https://www.pprune.org/tech-log/599702-descent-profile-when-cleared-ils-approach-3.html#post10421989
https://www.pprune.org/tech-log/599702-descent-profile-when-cleared-ils-approach-3.html#post10422013
:E