Primarily for general aviation discussion, but other aviation topics are also welcome.
#1858791
Paul_Sengupta wrote:I'm sure I've read somewhere that there are some which will offset your track by something like up to half a mile for this very issue?


That's not much good for IFR OCAS in UK, where I need to fly my planned route so that I know my MSA is accurate and to remain out of CAS with the margin I intended. For this to work I do want to be accurately on the magenta line because that's my planned track. My goal is to place that line where others are unlikely to do so. Using the offset function makes things awkward because then I have to program a line that is offset from the line I planned.

I do the same when flying VFR with Skydemon. When I've got no desire to meander, I fly the line accurately, but I place the line where I hope others haven't.

I get the impression the offset function is intended for airliners flying in distant parts of the world where available airspace isn't an issue.
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By Paul_Sengupta
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#1858810
rdfb wrote:That's not much good for IFR OCAS in UK, where I need to fly my planned route so that I know my MSA is accurate and to remain out of CAS with the margin I intended. For this to work I do want to be accurately on the magenta line because that's my planned track.


I'm not sure I understand, how does being, say, a hundred yards to the right affect anything? Surely if you were using "old" navigation using VORs or even NDBs, you'd be lucky to be within a hundred yards when at a fair distance from the beacon?

rdfb wrote:My goal is to place that line where others are unlikely to do so. Using the offset function makes things awkward because then I have to program a line that is offset from the line I planned.


Hmm? You plan a line, then the offset is done for you, so you don't have to plan a line where others are unlikely to be, you can be VOR to VOR, say, in the knowledge that you're not going to encounter someone doing the same in the opposite direction.

rdfb wrote:I get the impression the offset function is intended for airliners flying in distant parts of the world where available airspace isn't an issue.


Or anyone who doesn't want to hit someone coming the other way. Remember when VFR flying along a line feature, you were supposed to fly to the right of it? You could program an "offset" which says, "Put the magenta line 100 yards right of the direct track from VOR A to VOR B."
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#1858864
Paul_Sengupta wrote:I'm not sure I understand, how does being, say, a hundred yards to the right affect anything? Surely if you were using "old" navigation using VORs or even NDBs, you'd be lucky to be within a hundred yards when at a fair distance from the beacon?


IIRC, the minimum offset on a GNS430 is 1nm. That's quite significant. If near controlled airspace, it halves the margin if I'm "taking two", and as we know, OCAS is often too crowded for that to be possible anyway. If near MSA (which is most of the time for IFR OCAS IME), moving the line by a mile often raises the MSA. - because I've already had to plan very carefully to find a route where the MSA is low enough - particularly for a leg where I intend to descend to find VMC because my destination aerodrome has no instrument approach.
Paul_Sengupta wrote:
rdfb wrote:My goal is to place that line where others are unlikely to do so. Using the offset function makes things awkward because then I have to program a line that is offset from the line I planned.



Hmm? You plan a line, then the offset is done for you, so you don't have to plan a line where others are unlikely to be, you can be VOR to VOR, say, in the knowledge that you're not going to encounter someone doing the same in the opposite direction.


200 yards would be fine. But when the minimum offset is a mile, I have to be planning for the actual offset line, and not my original not-offset line. Because, in the UK OCAS, there are narrow gaps, and I risk infringing CAS, ATZs and breaking the "5 miles, 1000 feet" terrain clearance rule otherwise.

Paul_Sengupta wrote:Or anyone who doesn't want to hit someone coming the other way. Remember when VFR flying along a line feature, you were supposed to fly to the right of it? You could program an "offset" which says, "Put the magenta line 100 yards right of the direct track from VOR A to VOR B."


I think maybe the misunderstanding here is that you think a 100 yards offset is programmable, when it is not? For VFR, I just move my waypoints a bit in Skydemon and then fly that - so I'm never flying directly between public waypoints. Actually to keep Skydemon's plog sane, I have a bunch of custom waypoints that are offset that I use instead. My point is that this approach is tedious and error-prone for typical IFR navigators. The offset function isn't suitable, and nor is entering every waypoint lat/lon manually.
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By Paul_Sengupta
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#1858874
rdfb wrote:I think maybe the misunderstanding here is that you think a 100 yards offset is programmable, when it is not?


Ah, ok, I wasn't talking specifically about the GNS430, it was just a generic comment about an offset, I didn't know you could do this in a GNS430 and that the minimum was 1nm.
#1859057
The Garmin 'GPS II Plus' ("hiking") b&w GPS was the first GPS I got, as an end-of-line bargain (very cheap :) ) from a Harry M stand at a PFA Rally. I used it for all my GA flying, supplementing SD on a tablet when I got that on one of those much later.

User has to create own waypoints, using lat/long manually entered, and then routes linking them. On the move, desired track and current position related to it are displayed on a 'Highway page'. This consists of a clear track-up 'road' with a centre line, 9 'CDI marks' wide, then a grey area 2 CDI marks wide on either side (if one's close enough to desired track), or (if not) all-grey with direction marker and true azimuth value and distance to rejoin desired track. CDI scale is user-settable at 0.25 (default), 1.25 or 5 sm (default) or km (also user-settable). Thus, the default shows clear 'road' 1 sm on either side of centre line, and further grey area 0.5 sm on either side of that.

Using that default, it was very easy to fly ~0.5 sm to one side of waypointed track (the centre line), having created waypoints from 'features' whose lat/long was available from documents like airfield guides, ERSs, etc; although I always checked these from OS or (latterly) online maps, having once found an E/W error (printed in an ERS) for an airfield very near the 0 Meridian.
By TopCat
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#1859111
Ibra wrote:Back to the serious stuff :thumleft:

https://www.faa.gov/regulations_policie ... fh_ch6.pdf

Other than in the circuit, where I correct for the wind without really thinking about it, I doubt I could do any of that properly without some practice.

Is it in the UK syllabus these days? I recall some drift appreciation stuff but no accurate ground reference turns.
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By AndyR
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#1862884
Hooligan wrote:
Had a FCL Navajo orbiting the LON VOR in the wee hours a couple of years ago - I'm about 18 miles from the VOR and I saw him passing about two miles further out at two or three thousand. Flying a perfect a circle or so it appeared on ADSB, he did several laps.


Was probably me. One orbit to assess. Next orbit after any required adjustments. Next orbit for the standby transmitter. Preferred accuracy +/- 0.02NM and +/-25ft. Hand flown but with a bit of magic to assist the skill :wink: Still hard work but very satisfying.
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