You are here:

Aviation/Flying/ILS Approaches - Simulator


I'm 16 and I've wanted to go into aviation all my life - I'm due to start actual training in a few months, but up till now my only experience in the cockpit has been behind a computer.

A question however - I've been plagued by this for a good few years, and I've finally got about to asking: Whenever I fly an ILS approach, I have to fly it manually. If I set the autopilot to Approach, with the NAV1 set to its desired approach frequency, the autopilot will always bring me down short of the runway threshold - and not just a few meters short - sometimes as far as 2 miles short! The bearing will be more or less spot on, and if I slew forward before I crash, it would have brought me down perhaps a meter to the left of the center line. Strangely, the autopilot will actually CLIMB to about 8,000ft, then dive down at something crazy like VS -3500, level off at 500ft above the ground, then dive again. Is this a bug in the simulator, or has this been known to happen before? Am I missing something? My usual procedure to land during an IFR flight is to set my NAV1 frequency to the ILS approach, follow the controllers instructions - "until established on the localiser", - then when I'm lined up on the ILS display, I hit the APP switch.

Is there something I missed?


Simulators are imperfect. Autopilots are subject to aberrations. One should always fly ILS manually (in my opinion, from experience).  If you rely on an autopilot approach all the time, when it becomes necessary to fly one manually (autopilot inoperative) you won't have the background (recent) practice. You won't be tested with an autopilot, but as a manual operator.
ILS uses a UHF radio path, usually programmed to provide a 3-degree glide slope in consonance with a VHF directional beam.  The glide slope is set from the point of transmission, and tuned for a specific approach.
For example, imagine a 360-180 degree runway.  The transmitter for the 360 heading approach is at the north end of the runway.  If you use that frequency for a 180 heading approach, the glide slope will be in error by the length of the runway.
The basic instruction always applies: FLY THE AIRPLANE.  Instruments are AIDS!  Autopilots have killed more than one human pilot. The most dependable instrument approach aid is eye-connected-to-brain, that governs hands on stick and throttle.  Even if an autopilot is engaged and functioning, hands should be ultimate guides.
Do not get into an airplane (as a pilot) with which you're not totally familiar with how everything works in that particular machine.  Ditto, simulator (a limited representation of actuality).
In any case, ILS tuned autopilots should not be engaged prior to the final approach fix. The programmed parameters are unreliable to some degree prior to that point.


All Answers

Answers by Expert:

Ask Experts


Bud Martin


General solutions to training problems, options in performance, selecting alternatives, how it was, criterions for excellence, and if one has to ask, an answer is needed.


Soloed @14 ('45) -- N73BM (Jeannie's Teenie) to C-5A (and everything in between), worldwide USN/USAF, never made a bad landing.

©2017 All rights reserved.