Learning to fly, or thinking of learning? Post your questions, comments and experiences here

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By Micromouse
FLYER Club Member  FLYER Club Member
#1876018
Something came up in a mock skills test yesterday.

You find yourself off your track. You need to correct obviously

Do people correct to arrive at the destination. or correct to get back on track and then continue on your original track?

Is this the equivalent of North up/Track Up, i.e a matter of personal choice?
By johnm
FLYER Club Member  FLYER Club Member
#1876027
A lot depends on how far you are from your destination or next waypoint. Typically you’d aim to get to your next waypoint to ensure you were still reasonably sure of your position
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By VRB_20kt
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#1876029
There are numerous ways to get back on track - just pick the one that works for you.

Having said that, on short legs it's rarely worth getting back on track - just aim to arrive at the turning point/destination.

From an airmanship perspective, there are some places where being off track can cause problems - notably near to controlled airspace/danger areas/obstacles etc. So like so much of aviation there is judgement involved.

As ever, discuss it with your instructor.
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By TopCat
FLYER Club Member  FLYER Club Member
#1876042
Micromouse wrote:You find yourself off your track.

How to correct depends on a few things, IMO.

- How do you know (ie, do you know exactly where you are now)?
- How much off track are you?
- How far is it till your next waypoint?
- How obvious are your waypoints, and how far away would you expect to see them?

For instance, back in the day when I had actual map reading skills, I would usually pick waypoints that were quite large and obvious, to make it easy to see them when approaching them.

It would then be obvious whether I was off track (eg wrong side of the town) as I approached. So I'd tend to recapture the track straightaway, and then make an appropriate heading change for the next waypoint.

Presumably you've been taught the 1 in 60 rule approach for calculating drift angle, and also the correction angle required to get back on track some multiple or fraction of the distance gone since the last one?

I always found that to be more trouble than it was worth, not least because it assumes extremely accurate maintenance of heading to be meaningful. Sometimes even DI precession errors can be bigger than unforecast wind drift, which makes the whole thing an exercise in futility, especially if the compass is bouncing around when you set the thing in the first place.

It also assumes the ability to know accurately how far off track you are. Two miles rather than one mile will double the calculated drift and correction angles.

I usually aimed to see any error appoaching a waypoint, get back on track by the time I got there, and then make a 5 or 10 degree heading change to compensate for the next one. If it needs much less than that, then your waypoints are probably too far apart.

I suspect for the test they'll expect some kind of 1-in-60-based correction, so do whatever seems easiest.

For a really gross error, such as setting the DI 30 degrees wrong and flying that for 10 mins, you'll be getting close to being lost, so forget any correction b0llocks and get to any large, clearly identifiable landmark so that you know exactly where you are before doing anything else.
By tcc1000
#1876073
The simplest is: if you can see where you are going, head for it.. (you might have to aim off). Once you reach your next turning point (or intermediate point), you are back on track and update timings accordingly.

I'd go for something that is easy to work out - something like if you are 2 miles off track, then turn 40 degrees in the direction to correct for 2 minutes, then turn 40 degress back again. If you think you've been flying accurately, then maybe that last turn is slightly less than 40 degrees so you have a corrected track. I think an instructor said this. IIRC, another added that you should add 2 onto the ETA as well. I thought about this for a little, then twigged that it's a 1 in 60 rule again. If you assume you are flying at 90 knots (not a bad guess for a training aircraft, especially as we actually want TAS which will be a bit higher than IAS), then you are flying 40/60 * 90 = 60 knots back towards the correct track - 1 mile a minute. As for the ETA, you are still going approx 50/60 of the speed towards your destination, it is going to take a little bit longer, but not that much (as also remember you've been flying the wrong way up to now, so you won't be quite as far towards your destination as you would have been had you gone straight.
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By QSD
#1876135
I have tried many different systems over the years. I found all the 1 in 60 methods difficult. In fact anything that required any mental arithmetic was a bit too hard to do while flying an accurate heading and altitude. .

I finally settled on the Standard Closing Angle technique and that is what I teach my students now. For example, TAS 90kts, 2 miles left of track: turn right 20 degrees and fly for four minutes. This should put you back on your original planned track so you can resume your original heading, suitably modified for whatever took you off track in the first place.

I like this system because it doesn’t need any calculation, other than doubling a small number, it also gets you back onto your carefully planned track rather than direct to your next turning point over unplanned territory. All you need to know is the SCA for your TAS. The disadvantage is that it doesn’t work for large errors - if you have a 25 degree track error, then turning 20 degrees won’t get you back. TBH, if you are 25 degrees off track, the you should probably go back and start again anyway.

I do have a PowerPoint briefing on the technique which I am happy to share - pm me if interested.
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By David Wood
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#1877371
Or, even simpler… because most students struggle to estimate distance in the air, assess your angular error at the half-way point (say 10 degrees off track) and make a 2x correction at that point. If at the 3/4 point make a 3x correction. Both aim to get you to your waypoint, not back on track per se.
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By GrahamB
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#1877413
David Wood wrote:Or, even simpler… because most students struggle to estimate distance in the air, assess your angular error at the half-way point (say 10 degrees off track) and make a 2x correction at that point. If at the 3/4 point make a 3x correction. Both aim to get you to your waypoint, not back on track per se.

I’m not sure I follow your first statement.

You need a chart to assess angular error; with a chart you can assess distance off track just as easily.

In fact I’d go as far as saying that without tools (e.g..fan lines, protractor, ruler) it’s easier to eyeball a distance on a chart than an angle.
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By johnm
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#1877414
and there's always the 10 nm thumb on a 1:500K :D
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By GrahamB
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#1877431
johnm wrote:and there's always the 10 nm thumb on a 1:500K :D

Exactly!
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By David Wood
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#1877432
GrahamB wrote:
David Wood wrote:Or, even simpler… because most students struggle to estimate distance in the air, assess your angular error at the half-way point (say 10 degrees off track) and make a 2x correction at that point. If at the 3/4 point make a 3x correction. Both aim to get you to your waypoint, not back on track per se.

I’m not sure I follow your first statement.

You need a chart to assess angular error; with a chart you can assess distance off track just as easily.

In fact I’d go as far as saying that without tools (e.g..fan lines, protractor, ruler) it’s easier to eyeball a distance on a chart than an angle.


I suppose that what I was getting at is that most students I've come across don't measure the distance by reference to the chart, they tend to do it by eye. And their estimates vary wildly.

At the end of the day this is one of those things where there is more than one right answer.
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By Paul_Sengupta
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#1878205
Harry.Brown wrote:For VFR navigation we never teach correcting to destination but correcting to the final waypoint before destination which we call the entry point. ... Students don’t pass this point ( which they can circle if they wish) until they have the destination positively identified


Hah, If this were the case when I did my PPL, I'd never have landed! Indeed, nor in the first year of my PPL before I bought an early moving map GPS. It would be the case of "Where is it? Is that it?" I even had that coming back to Popham last night *with* GPS as it was 6 minutes to dark as I approached.
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By skydriller
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#1878400
MattL wrote:Are you a U.K. instructor @Harry.Brown ? Never heard of this entry point stuff. Where you describe doing pre landing checks is far too early as well.


Dont recall it being called "entrypoint" or anything, but I do remember being taught that at some aerodromes you cant do the traditional thing of departing from the overhead or arriving in an overhead for an aerodrome, and so used a really obvious landmark as the nav start/finnish point. Downwind pre-landing checks are just that though... done downwind or on long final etc before you land, not 5mins away.

Regards, SD..
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By Rob P
#1879863
skydriller wrote:Downwind pre-landing checks are just that though... done downwind or on long final etc before you land, not 5mins away.


Mine are invariably done before joining the circuit, so something in the region of five minutes before the wheels kiss the runway (for the first time :D )

From habit I still run a check again on short final (not red,blue, green as I don't have the required prop or undercarriage) but carb heat and mixture together, plus shoulder straps once again.

Rob P