Message posted by Dr Ron Milione on April 12, 2002 at 5:56:08 PST:

In response to Joerg question the aircraft must `fly the glideslope' vertically and `fly the localiser' course horizontally to a precision landing. These radio beams are so sensitive that autopilots can automatically fly them. At some airports with some airplanes and certified crew, the autopilot can actually fly the aircraft down the ILS to a landing (wheels on the ground!) Such autoland capabilities were demonstrated first by the British Aircraft Corporation Trident III aircraft in 1965 (Bil97).

The ILS may be flown either full (localiser and glideslope) or localiser-only. Both are approved approaches; the full ILS is a precision approach and the localiser-only approach a non-precision approach. Both require Distance-Measuring Equipment (DME) signals from the UNZ VOR to be available and indicated in the aircraft cockpit. There is also another non-precision approach, the VOR-DME Rwy 32 approach, which uses only azimuth information from the UNZ VOR and distance information from its DME. The approaches differ in how the profile is flown beyond the Final Approach Fix.

When flying the ILS, if the glideslope should suddenly not be reliably received, the approach may be continued, but it reverts to a localiser-only approach; that is, should the glide slope `go out' during an ILS approach, one immediately starts following and continues to follow the procedures specified in the localiser-only ILS approach. This should be no problem, of course, if all valid positions on the ILS approach are also valid on the localiser-only approach. The course information is identical, so the condition would be equivalent to suggesting that all legitimate vertical positions on the ILS are legitimate vertical positions on the localiser-only approach (but not vice-versa), so a valid ILS approach profile would also be a valid localiser-only profile.

Regards, Ron

In Reply to: Fastmover audio clip posted by Joerg (Webmaster) on April 11, 2002 at 16:52:43 PST:

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