help needed with Nav!!
Ideally use a larger SCA. But in practice it won't matter hugely as even with a smaller SCA, you'd be close enough to recognise the visual fixes when you'd finished your correction.
SCA is used by the RAF. Have to say the 'Visual Navigation' wasn't actually taught when I wen through CFS - they concentrated on low level navigation.
SCA is used by the RAF. Have to say the 'Visual Navigation' wasn't actually taught when I wen through CFS - they concentrated on low level navigation.
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Children - no need to argue about techniques. They all work, all are accurate enough for the purpose. Some people find one easy, others prefer another. All have certain disadvantages.
Teach your students a technique you think is appropriate to their abilities, and if they don't get on well with it then get them some practice on the ground with other methods, until you find one that works! It ain't that difficult
BEagle
Is perhaps the most ridiculous statement I have seen in a supposedly serious discussion of instruction. You have decided it is no good because it is too difficult to work out to 8 significant figures, yet the method you advocate is (like 1:60) only accurate to the nearest couple of degrees. For anyone with any practice in mental arithmetic the maths is very easy, as long as you only expect a rough answer, which is all that is possible in the air.
Some of my ATPL groundschool students use 1:60 when flying. I've used it for a lot of flying, was taught in the Navy and believe me there were a few pilots who were not terribly bright. The reason it is in the ATPL exams is because the RAF use it, and they certainly aren't known for intelligence
If they can manage it then it's worth offering your students as an option, and keeping an open mind.
Teach your students a technique you think is appropriate to their abilities, and if they don't get on well with it then get them some practice on the ground with other methods, until you find one that works! It ain't that difficult
BEagle
Which is why 1/60 is NFG for pilot navigation.
Some of my ATPL groundschool students use 1:60 when flying. I've used it for a lot of flying, was taught in the Navy and believe me there were a few pilots who were not terribly bright. The reason it is in the ATPL exams is because the RAF use it, and they certainly aren't known for intelligence
If they can manage it then it's worth offering your students as an option, and keeping an open mind.
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I tried SCA method in the sim. I was 4 miles off course heading north- I set the wind to 270/30 and my TAS was 90kts. However, I held this for 4 minutes turned 40 deg and I was still off course by 2 miles!!????
Anyone??
Anyone??
Your original data set was incomplete and the conditions you used were non-representative. Basically, you did not emulate a navigation problem........
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fuddgy,
Try the same flight however this time use drift lines to measure the angular error caused by following your heading. Having measured how long you have been maintaining that heading, doubble the error towards track and in a equal time you should be back on track.
With a wind of 270/30, the heading required to track North at 90Kt is about 337.
To look at it another way, if you steer 360 in that wind you will track 023 degrees.
Having maintained heading 360 for say 5 minutes, you turn left by (2*23)=46 deg heading 314 for a further 5 minutes where upon you will be reasonably back on track where you turn right by 23 degrees heading 337 to maintain a northerly track.
You don't have to be a genius to work out that correcting into wind will leave you a little short while correcting out of wind will make you overshoot slightly. However, the whole idea is to get you bak within a reasonable distance of your planned track and provide you with a correction that will keep you on or near that track.
---
BEagle,
I'll leave the SCA explanation for this case to you.
Regards,
DFC
Try the same flight however this time use drift lines to measure the angular error caused by following your heading. Having measured how long you have been maintaining that heading, doubble the error towards track and in a equal time you should be back on track.
With a wind of 270/30, the heading required to track North at 90Kt is about 337.
To look at it another way, if you steer 360 in that wind you will track 023 degrees.
Having maintained heading 360 for say 5 minutes, you turn left by (2*23)=46 deg heading 314 for a further 5 minutes where upon you will be reasonably back on track where you turn right by 23 degrees heading 337 to maintain a northerly track.
You don't have to be a genius to work out that correcting into wind will leave you a little short while correcting out of wind will make you overshoot slightly. However, the whole idea is to get you bak within a reasonable distance of your planned track and provide you with a correction that will keep you on or near that track.
---
BEagle,
I'll leave the SCA explanation for this case to you.
Regards,
DFC
Track closure rate at 90 kts with a 40 deg SCA is 90 sin 40. In 4 minutes, XTK error would have reduced by (4/60) x 90 sin 40 nmiles, i.e. 3.8567 miles. He should have been only .1433 miles (871 feet) off track after following the 40 deg SCA for 4 minutes - hence I can only assume that he didn't model the problem correctly...
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F2k
If you did what you said you would have been back on track!
You must have erred somewhere
Did you continue deviating from track whilst calculating the correction? That would have, of course, allowed the distance from track to increase still further
I'm having a smileyfest
If you did what you said you would have been back on track!
You must have erred somewhere
Did you continue deviating from track whilst calculating the correction? That would have, of course, allowed the distance from track to increase still further
I'm having a smileyfest
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I have tried this with RANT and it doesnt work!!!!
90kts, 40 degree turn, 270/30kt.
I set the alt to 0ft therefore not reading any slant distance with DME.
Moved my aircraft 2nm abeam DTY, pointing north. Applied wind and then turned 40 degrees, held for 2 minutes---still 1.2 miles off???
90kts, 40 degree turn, 270/30kt.
I set the alt to 0ft therefore not reading any slant distance with DME.
Moved my aircraft 2nm abeam DTY, pointing north. Applied wind and then turned 40 degrees, held for 2 minutes---still 1.2 miles off???
You wrote earlier that you'd tried SCA 'In the sim'. I didn't realise that you actually meant with some PC toy 'simulator' program...
Practise it in the air, chum (dual, of course!) - you're obviously doing something wrong with your PC!
Practise it in the air, chum (dual, of course!) - you're obviously doing something wrong with your PC!
Last edited by BEagle; 28th Mar 2004 at 13:37.
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BEagle - if a technique works then it should work on RANT, a system so simple that the variability even of a simulator has been removed, and results should be most consistent. I agree that fudgy must be doing something wrong, as although I have neither taught nor used the technique I am not aware of large errors, but that is not an excuse for being patronising. It in fact goes against your insistence that SCA is the only technique to use and infalibly simple! Perhaps fudge should simply be using a different method, that might suit him?
Unless I'm misreading your description, you positioned the a/c 2nm off-track then set a wind, turned i.a.w. the SCA method & flew for two minutes?
Where did the two minutes come from? From your description you started at the 2nm abeam position. I think the SCA method requires that you fly the track correctio for the same duration it took for the error to happen.
Where did the two minutes come from? From your description you started at the 2nm abeam position. I think the SCA method requires that you fly the track correctio for the same duration it took for the error to happen.
No, you hold the correcting track for the same numerical number of minutes as you were miles off track. N miles off track, turn through SCA and hold for N minutes, then reverse to original heading and correct DI, rudder trim. But if both those were OK, correct by applying observed drift value.
'Pointing north' - does that mean 'heading' or 'track', 'true' or 'mag'?
'Pointing north' - does that mean 'heading' or 'track', 'true' or 'mag'?
