[jhb_airlines] Re: Pilot Hours

  • From: "Bones" <bones@xxxxxxx>
  • To: <jhb_airlines@xxxxxxxxxxxxx>
  • Date: Tue, 21 Dec 2004 00:44:27 -0000

You've lost me there somewhere Frank.

NAV1 and NAV2 boxes can only be tuned to the frequency band 108.0 to =
which covers the ILS and VOR bands. ADF is a separate box covering 200 =
1700 medium wave for NDB's.

The autopilot has two directional modes - HDG or NAV (sometimes flagged =
CRS). Heading mode is by far the most useful (and used) of the two as =
can dial in a heading and leave the autopilot to fly this quite happily. =
you choose a different heading to fly the response is immediate as the
aircraft is responding directly to the input. Heading mode is used when
flying under ATC radar instructions but it is also useful to set an =
course if you haven't got the nav boxes tuned in for NAV or CRS flight.

NAV or CRS mode is used when flying an ILS beam or tracking a VOR on a
specific radial. In both cases you a flying along a predetermined beam - =
ILS being a fixed direction whilst the VOR is user selectable. By =
setting a
value in the NAV box you are selecting that specific radial to track to =
from) the navaid you have tuned to.

In this case the autopilot is a bit more intelligent in that it will try =
intercept the VOR radial (if you give it a chance) and will then fly =
that radial automatically correcting for any wind drift. I say you have =
give it a chance because there are some scenarios which are simply too
impossible for the autopilot to intelligently assess. The ideal =
either to intercept a VOR or ILS, is to be on a closing heading of about =
degrees to the required flight path and at least 10nm away from the =
Any steeper or closer and the autopilot will capture the beam but you =
end up snaking down the beam as the autopilot tries to lock on to a more
increasingly sensitive signal.

Likewise it is very difficult to lock onto a VOR radial if you are =
over the beacon. It has a nominal cone of silence that can be as much as =
or 4nm if you are flying at high altitude and the autopilot will simply =
up if it can't recognise a good signal. Thirdly, you won't capture a =
beam if
you are flying away from it. If you set yourself up to capture a VOR =
from a
nice closing heading but have already gone through the signal then the
autopilot may not pick it up at all. It will if you are still close to =
beam but you don't have to go far to get outside the capture segment.

So, for NAV or CRS mode on the autopilot you should stick to NAV 1 for
tuning your beacons. For NAV 2 and ADF you have to stay in HDG mode and
assess a good heading to fly to the beacon.


-----Original Message-----
From: jhb_airlines-bounce@xxxxxxxxxxxxx
[mailto:jhb_airlines-bounce@xxxxxxxxxxxxx] On Behalf Of frank fisher
Sent: 20 December 2004 23:03
To: jhb_airlines@xxxxxxxxxxxxx
Subject: [jhb_airlines] Pilot Hours

JHB117c EGGP EGNC 2110 2224 01:14

touch and go

JHB 118c EGNC EGNT 2224 2255 00:31

Still struggling with radio nav, can lock on to the first beacon, then
unable to lock and hold second, NAV2 is ADF, so had both NAV1 and 2 set =
same FRQ, set ADF and followed the needle. Must be doing some thing =
someware. Frank F

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