first shot answer.not looking anywhere else like wikipedia, so i could be wrong...did ATPL thousand years ago.
1.internal system drive unit, thats the unit which keep the system at 400hz to run the generator.it s the whole unit, constant speed drive + generator= ISDU, this unit is connected by gears to the engine.
2.clearance altitude, restricted altitude. (clearance is for obstacle, restriction could be for sound by example , ...
3. ILS are separated by 0.5 herz, and can offer only 12 different ILS in the VHF band allowed from .111.9 to 117.9mhz. you want several ILS in case of multiple runways. Each runway can have its own frequency for making parrallel approaches. remember 112,118,124,132 ILS/VOR and VHF range
4. moutain when top is higher than 2000ft. (600meters).
below this it s called hills.
Last edited by captainsuperstorm; 28th May 2011 at 05:06.