Standard Closing Angle - again!!
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Standard Closing Angle - again!!
I know that this topic for basic VFR navigation has been raised before - and that it has its sceptics - but it was very interesting to note that very senior ex-CAA Examiners were pushing SCA very strongly to a group of some 50-odd FIs last week at the ETA seminar. And it was also explained that getting back onto track rather than direct to the turning point WAS what was expected in every day use in airways!!
However, the speaker did say that there is one person who thinks that SCA is 'track crawling' - and that person talks a load of rubbish!!
However, the speaker did say that there is one person who thinks that SCA is 'track crawling' - and that person talks a load of rubbish!!
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Yes BEagle it was moi who first raised the issue of Standard Closing Angle in response to someone asking the easiest and most effective way of correcting track. Its good to see CAAFU accepting it as they never used to be too keen on it! I agree with you, to say its 'track crawling' is rubbish.
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You've got to be a little bit careful applying SCA to light piston aircraft because of the size of the correcting angles you end up with. It's all very well to use an SCA of 10° when you're whizzing along at 360 kts in your Hawk but, in a PA28 doing 100 kts, a head/tail wind can change the SCA from 30° to 60°. In addition, in both these cases you're operating outside small angle theory on which the whole thing is based. It can be useful but you've got to understand its limitations.
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True - but the whole idea is to get the pilot back closer to track so that pre-planned visual fixes can be identified and overflown and then the heading corrected for changed W/V. The major flaw in the presentation made at the ETA seminar was that the speaker talked only of G/S and not TAS. I didn't wish to correct him as his presentation was weak in other areas as well - but the SCA meessage certainly came across!!
Originally posted by BEagle on the In Flight Navigation techniques thread:
'Standard Closing Angle' is the simplest method we've found for correcting tracking errors and 'proportional correction' for timing errors. No need for lines on the chart such as those ancient 5 deg and 10 deg driftlines!! And no hard sums either. To summarise:
STANDARD CLOSING ANGLE
1. Establish your distance off track.
2. Turn towards track by a Standard Closing Angle of 60/(TAS in miles per minute) i.e. 40 deg for a 90KIAS Cherokee, 30 deg for a 120KIAS Bulldog.
3. Hold that heading for the same NUMBER of minutes as you were miles off track , i.e. 3 minutes if you were 3 miles off track.
4. Turn back onto original heading , recheck DI is synch'd and the rudder trim is correctly stopping flight with a constant yaw.
5. Adjust timing by adding 1/3 of the time spent on the Standard Closing Angle at 90KIAS or 10 sec per minute at 120KIAS.
It's easy and it works!!
STANDARD CLOSING ANGLE
1. Establish your distance off track.
2. Turn towards track by a Standard Closing Angle of 60/(TAS in miles per minute) i.e. 40 deg for a 90KIAS Cherokee, 30 deg for a 120KIAS Bulldog.
3. Hold that heading for the same NUMBER of minutes as you were miles off track , i.e. 3 minutes if you were 3 miles off track.
4. Turn back onto original heading , recheck DI is synch'd and the rudder trim is correctly stopping flight with a constant yaw.
5. Adjust timing by adding 1/3 of the time spent on the Standard Closing Angle at 90KIAS or 10 sec per minute at 120KIAS.
It's easy and it works!!
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If a student could recognise when he is ON Track, he probably wouldn't get off it in the first place. Now if he can't recognise the ON Track case how does he recognise the OFF Track case? and measure how far it is from something he couldn't identify in the first place. Turning right or left 40 degrees in the vain hope of regaining this unrecognisable Track in X minutes is expecting rather a lot of some students who will merily go off to practice their lost procedure in the opposite direction. I don't recall anything that requires a PPL student to fly a Track, FCL 684 certainly doesn't.
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So how, Blue Line, do you expect your student to recognise that he/she is 'on track'? By constant map-reading and track crawling?? If they do that they WILL fail the PPL Skill Test. It's all to do with quantifying error and correcting it in a rigorous manner. And turning through large SCAs such as 40 deg is fine - but only if the timing error is allowed for. As I've suggested, 1/3 minute per minute at 90 kts is easy to work out whilst flying on the SCA.
Anyway, I've said it all before, but the purpose of this thread was to let you know that it is now being given firm backing by senior people in the PPL Examining business - it's not just me!!
Anyway, I've said it all before, but the purpose of this thread was to let you know that it is now being given firm backing by senior people in the PPL Examining business - it's not just me!!
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Blueline
I disagree. Maybe it is possible to stay completely on track in the UK, but I had a dual cross country today (in NZ) where even though there was only one area of cloud over 250 track miles, it forced us off track. There are situations where a cloud layer sits on top of a range of hills (in todays case at 4000') and we simply can't go under or over or through, we have to go around.
While not appropriate for second X/C, something like SCA would be immediately useful in this application because the student knew exactly where the track was on the near side of the range, but when we went five miles to the side to go around the cloud it was hard to estimate where the track came out the other side (imagine trying to find the other side of a 2 mile train tunnel through a mountain range from about five miles away when you can't see where it went in).
In this case (and many others in NZ - topography seems to dictate quite a bit of our destination success) a knowledge of SCA would be highly valuable. I believe it should be taught - if not to PPL students then at least to post PPLs looking for something extra to stop them fiddling with the wizzy wheel. I remember finding out about it from an ex 747 captain two months ago, and it was one of those situations where I thought, "Why wasn't I taught this when I was learning?". Now of course I realise that I will always have something to learn, often the simple ways of doing things
Safe flying
I disagree. Maybe it is possible to stay completely on track in the UK, but I had a dual cross country today (in NZ) where even though there was only one area of cloud over 250 track miles, it forced us off track. There are situations where a cloud layer sits on top of a range of hills (in todays case at 4000') and we simply can't go under or over or through, we have to go around.
While not appropriate for second X/C, something like SCA would be immediately useful in this application because the student knew exactly where the track was on the near side of the range, but when we went five miles to the side to go around the cloud it was hard to estimate where the track came out the other side (imagine trying to find the other side of a 2 mile train tunnel through a mountain range from about five miles away when you can't see where it went in).
In this case (and many others in NZ - topography seems to dictate quite a bit of our destination success) a knowledge of SCA would be highly valuable. I believe it should be taught - if not to PPL students then at least to post PPLs looking for something extra to stop them fiddling with the wizzy wheel. I remember finding out about it from an ex 747 captain two months ago, and it was one of those situations where I thought, "Why wasn't I taught this when I was learning?". Now of course I realise that I will always have something to learn, often the simple ways of doing things
Safe flying
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Chicken6,
lets not confuse diverting around an object with sensible track keeping. The equilateral triangle is really a form of SCA and allows you to simply divert around a feature CB or whatever.
Most PPL students get about 4 hours navigation training and have to demonstrate an ability to reach turning points on a navex to plus or minus 3 minutes. Techniques developed for military jets that have a requirement to stay on track are not always appropriate to 90 knot PPL students who find it quite difficult to calculate anything in the air. My concern is that large turns away from track are likely to finish up with more lost students at the end of the day.
Now where does a 250 mile long track fit into PPL training? The longest in the UK is typically not more than 60 miles.
lets not confuse diverting around an object with sensible track keeping. The equilateral triangle is really a form of SCA and allows you to simply divert around a feature CB or whatever.
Most PPL students get about 4 hours navigation training and have to demonstrate an ability to reach turning points on a navex to plus or minus 3 minutes. Techniques developed for military jets that have a requirement to stay on track are not always appropriate to 90 knot PPL students who find it quite difficult to calculate anything in the air. My concern is that large turns away from track are likely to finish up with more lost students at the end of the day.
Now where does a 250 mile long track fit into PPL training? The longest in the UK is typically not more than 60 miles.
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Chicken6,
For diversions all you need to do is:
1. turn left or right as required by 60 degrees for maybe 3 minutes (depending how big your diversion is)
2. parallel track until clear of diversion
3. turn 60 degrees back towards your original track for 3 minutes (the same time you used in 1)
4. turn back onto your heading to maintain track
It works well for your 90 knot student type aircraft and you don’t need to get your whizz wheel out. In fact I always leave my whizz wheel in the club because in the air you should be using the above, SCA and LOOKING OUT!
I’m jealous of your x country in NZ! The last time I was down there the only x country I got was on that wonderful train of yours; complete with sheep skin covers on all the seats and free peanuts. Knocked the spots of our old British Rail
Vigi
For diversions all you need to do is:
1. turn left or right as required by 60 degrees for maybe 3 minutes (depending how big your diversion is)
2. parallel track until clear of diversion
3. turn 60 degrees back towards your original track for 3 minutes (the same time you used in 1)
4. turn back onto your heading to maintain track
It works well for your 90 knot student type aircraft and you don’t need to get your whizz wheel out. In fact I always leave my whizz wheel in the club because in the air you should be using the above, SCA and LOOKING OUT!
I’m jealous of your x country in NZ! The last time I was down there the only x country I got was on that wonderful train of yours; complete with sheep skin covers on all the seats and free peanuts. Knocked the spots of our old British Rail
Vigi
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This is what PPRuNe is for!!!! Serious discussion at last, this is brilliant.
Blueline
250 mile X/Cs appear in NZ because that's how long it takes to go somewhere from here if you don't want to go to Wellington (and by XC #2 we don't thankyouverymuch!)Also a slight exaggeration on my part, the distance was only about 180 nm.
After looking at the atlas, and remembering a 1:250,000 map sent from one of our English correspondents, I can see where you are coming from, but we simply don't have the concentration of airfields that you do. While you have a town every 2-5 nm, we have a town every 10. Airports are generally about 20-40 nm apart (in this region at least). 180nm is how far it takes to go to three different ones taking in different flight conditions (real mountains with funnel winds, turbulence (not too much though) etc), and the distinct possibility of having to divert for a whole host of reasons. Just because 800nm would take you all around England doesn't mean you're in a big country (no offence) and IMHO the sizes of the tracks in our different countries don't really matter, it's what you do with them
Check out the atlas, see how many Englands you can get into NZ, then divide the population by (? don't know! pop'n here about 3.8M) and spread them out - get the picture? Add scenery of Ireland, Canada and a touch of Norway and France (scenery, not class!) and that's Aotearoa. Not much to follow looking down, but what there is is good precisely because there isn't much.
You said that large turns off track would result in more lost students - I agree, but only if they start thinking about too much. The trick here (as I see it) is to get them thinking about where they want to end up and how to get there - never mind the maths except how much time required, how much fuel left, how much time left. Compare 1 and 3, decide early. And above all, Aviate then Navigate, Communicate.
Vigi
Glad you enjoyed it! you should come flying here even for 20 min. - for the last few days once we got above the inversion at about 2000' we could see for about a hundred and something miles (no exaggeration this time). And I live here!
Safe flying
Blueline
250 mile X/Cs appear in NZ because that's how long it takes to go somewhere from here if you don't want to go to Wellington (and by XC #2 we don't thankyouverymuch!)Also a slight exaggeration on my part, the distance was only about 180 nm.
After looking at the atlas, and remembering a 1:250,000 map sent from one of our English correspondents, I can see where you are coming from, but we simply don't have the concentration of airfields that you do. While you have a town every 2-5 nm, we have a town every 10. Airports are generally about 20-40 nm apart (in this region at least). 180nm is how far it takes to go to three different ones taking in different flight conditions (real mountains with funnel winds, turbulence (not too much though) etc), and the distinct possibility of having to divert for a whole host of reasons. Just because 800nm would take you all around England doesn't mean you're in a big country (no offence) and IMHO the sizes of the tracks in our different countries don't really matter, it's what you do with them
Check out the atlas, see how many Englands you can get into NZ, then divide the population by (? don't know! pop'n here about 3.8M) and spread them out - get the picture? Add scenery of Ireland, Canada and a touch of Norway and France (scenery, not class!) and that's Aotearoa. Not much to follow looking down, but what there is is good precisely because there isn't much.
You said that large turns off track would result in more lost students - I agree, but only if they start thinking about too much. The trick here (as I see it) is to get them thinking about where they want to end up and how to get there - never mind the maths except how much time required, how much fuel left, how much time left. Compare 1 and 3, decide early. And above all, Aviate then Navigate, Communicate.
Vigi
Glad you enjoyed it! you should come flying here even for 20 min. - for the last few days once we got above the inversion at about 2000' we could see for about a hundred and something miles (no exaggeration this time). And I live here!
Safe flying
