It looks to me like the designers have decided that 3.15° is
the steepest angle/profile they are willing to publish. This will only get the aircraft to 1600ft by the MAPt. The angle required to get to 1500ft by the MAPt is 3.58°, or 380ft/nm, as mentioned. As JAR has pointed out, the profile table is only a recommendation.
This is quite tricky because, the distance between the LOM and the VOR is so short: if you were level at LOM at 2300ft, you'd never comfortably get to 1500ft by the VOR. We have to be "descending passing" LOM at 2300ft on the way down.
To get the advantage of the extra 100ft, the solutions, as I see it, are:
- When passing the LOM (assuming you are already established in, or your FMS database provides, a 3°-ish profile prior to LOM), set VS 1000ft/min. This will get you pretty close to the MDA by the VOR (in effect, a dive with no drive);
- Determine and then fly a constant 3.6° approach from say 3000ft, to achieve 1500ft at the VOR, ie DMEx380ft/nm + 1500ft.
Originally Posted by Denti
my LIDO chart shows a CDFA approach out of 3300 (3500 if starting the approach out of LENIZ) with 3.15° passing the MAPt at 1500.
I don't understand that. One can't fly a CDA at 3.15° from LOM and achieve 1500ft at the VOR. The slope required from LOM is 3.58°. If one flew 3.03° from LENIZ, you'd go under 2300ft passing the LOM.