Originally Posted by DC 9 Driver
Gilles wrote
"How does one verify that one is on the correct vertical path by 500 AGL or 100' above the MDA when doing a a LOC approach ?" In this case, an Airbus on LOC 05 to YHZ,
by correctly setting the published FPA at 0.3 DME from the FAF, then pull the knob.
...No offense Gilles, but sometimes I wonder if the people on this thread are actually pilots, familiar with the automation in Airbus and Boeing aircraft.
A bit harsh, there DC9. What you have described
might put an aeroplane on the correct path just after the FAF (you did cross the FAF in a 3° descent, I hope, so there was no balloon into the final descent...), but certainly doesn't ensure you will
remain on that path. Unless you have an FMS-generated VNAV path to follow/coupled to, you'd better be following the DME profile down to the MDA (as FFbob noted) because what you've described is simply a point-and-shoot exercise, with you hoping you'll pop out with 2W/2R on the PAPI.
To Rat you said:
Originally Posted by DC9 Driver
As the ground speed varies, the aircraft position relative to the desired FPA is adjusted by the autothrust to maintain the correct FPA.
No it doesn't. If the aeroplane is bumped off the 3° path for some reason, it won't go back to it, it will simply re-set the flight path to 3°. The report describes this issue on page 65 and is something that any Airbus or Boeing driver should understand...
Further, I'm not an Airbus pilot but I very much doubt that the autothrust would control the vertical path: throttles control the speed, the pitch control controls the vertical path/FPA. That is what happens on my auto-jet. Just like they fly coupled ILSs. You get low, the stick comes back to correct. You get fast, the throttles come off.