Cold temp corrections on LNAV appr
Was wondering if anyone could help clarify this potential situation for me.
You are making an RNAV approach rwy 23L in Düsseldorf EDDL. The temp is -20 C. You can't use VNAV minima as you can only use this to -15 C. So you fly the LNAV minima which you can use (Airbus) NAV lateral guidance and selected vertical ( our procedures are FPA).
My companies procedures are to add temperature corrections to 1) DA/mda and 2) Non precision approach to minimum altitudes after passing the FAF.
So non temp corrected profile 23L RNAV is platform 3000ft descent at 8.8 nm (from rwy) 3 degrees with alt checks at 7nm =2420 6nm=2100 4nm 1470 and 3nm 1150.
So if I apply temp corrections to check heights after FAF according to our procedures then to be at 7nm =2740 6nm 2370 4nm 1650 and 3nm 1290.
My question is If I fly platform at 3000ft indicated as according to our procedures then the next check height from 8.8nm to 7nm is only 260ft height to lose instead of 580ft. This means if I want to start descent iaw the proc at 8.8nm then I would only need an FPA of about -1.5 instead of the usual FPA of -3 then at 7nm increase the FPA to ~-3 again.
Another option would be stay at 3000ft till 7.7nm then do -3fpa.
Am I right in my thinking or am I missing something very obvious?
Any help much appreciated.