How to Navigate visually??
Join Date: Aug 2002
Location: Brisbane Australia
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clearos, and lots of em!
i only skimmed some of the logner replies so apologies if i repeat something allready said...
if you can, do go track as heading and use a navaid to work out your wind correction. VOR's preferably, if theres one handy.
navaids are there to be used. Of course chances are you'll have them switched off quickly so make trhe most of them while you have them
and clock to map to ground is VITAL.
i only skimmed some of the logner replies so apologies if i repeat something allready said...
if you can, do go track as heading and use a navaid to work out your wind correction. VOR's preferably, if theres one handy.
navaids are there to be used. Of course chances are you'll have them switched off quickly so make trhe most of them while you have them
and clock to map to ground is VITAL.
I assume you are in an aeroplane, which is stable, trimmed, and wants to hold its heading. This is not the case in a helicopter, which wants to bounce all over the place and jiggle that stupid magnetic compass out of its bowl.
So, try this:
1. Over your first point, turn onto the TRACK for the leg, hold it steady, and look ahead. You will be drifting with the wind while shooting this sight line, so don't take too long.
2. Pick 3 features that are lined up on this track - maybe a shed, or distinctive treeline, or a funny hill, and REMEMBER them. (Don't fall for a shadow, as it is moving)
3. Now set up your planned heading, and check that it is taking you along the sight line. If it isn't, fix it. And write the new heading down.
4. As you pass over one sight point, pick another in the distance, still in line with the remaining 2.
IT WORKS!!
So, try this:
1. Over your first point, turn onto the TRACK for the leg, hold it steady, and look ahead. You will be drifting with the wind while shooting this sight line, so don't take too long.
2. Pick 3 features that are lined up on this track - maybe a shed, or distinctive treeline, or a funny hill, and REMEMBER them. (Don't fall for a shadow, as it is moving)
3. Now set up your planned heading, and check that it is taking you along the sight line. If it isn't, fix it. And write the new heading down.
4. As you pass over one sight point, pick another in the distance, still in line with the remaining 2.
IT WORKS!!
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Join Date: Mar 2003
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Thanks guys and gals for all the useful input. I am very impressed and you have all given me motivation to go out there and try some of them to see how well they work.
Keep them coming!! I think not only I am learning something here.
Very interesting stuff. Much appreciated!!
SQUALL
Keep them coming!! I think not only I am learning something here.
Very interesting stuff. Much appreciated!!
SQUALL
Some other stuff I just thought of...
** Fold your chart so that there is still a decent amount showing to the L & right of track and beyond your destination. Large features in those areas are useful for basic orientation.
** Make sure you're comfortable with some form of track correction calculation. This could be 1:60 (my preference), pre-drawn drift lines or whatever.
I like 1:60 because it's so flexible. It can be done in your head very quickly to an acceptable accuracy by memorising about 4 numbers:
If the distance run (or to run) is anywhere 60 nm then multiply the distance off track by 1 to get Track Error or Closing Angle. eg 57 miles since last fix. 5 miles off track = 5 deg TE. 68 nm to desired on track position = another 5 deg. Total HDG change = 10 deg.
If ~30 nm run/to run, multiply dist. off track by 2. eg 35 nm run, 3 off = 6 deg TE
If ~20 then x3
If ~15 then x4
If ~45 then x 1.5 --> this is an interpolation but good enough. After all, the whole of the 1:60 method is based on approximations!
If 120 nm then dist. off x a half.
** A fix or DR position isn't proven until the next anticipated fix occurs.
** Use a navigation log. That's a key part of navigating to somewhere that's unknown.
It doesn't have to be on some sort of form. Your map itself makes a very good log device. That's what I use.
Use the correct nav. symbols on your chart to remind you later in the flight about what sort of fix or position line you were able to get earlier. This helps tell you how much you can rely on that particular 'fix'/DR position.
Important things are Times, Headings & Groundspeed. TAS too if you're varying it a lot.
The common symbols include:
A dot with a little circle around it: a pinpoint ie you can prove you're over that position. Still subject to my earlier comment though
.
A dot with a little square around it: This is an AIR position ie where you would be having held HDG & TAS for xx mins. There is no wind effect in this.
If you add wind effect for that period time then you get:
A dot with a little triangle around it: this is a DR position ie where you THINK you are based on calculation eg have held xx HDG for yy mins @ zz TAS with this much wind effect therefore I should be 'here'.
A line with an arrow at each end: This marks a line of position. You're somewhere on that line. Two of these lines crossing give you a FIX. Use common sense about how long you draw the line.
This next is a bit more complicated & not often used. That said, I've happily used it a number of times before. It's just another tool to add to your box of tricks...
A dotted line with an arrow at each end. This is a 'running line of position' or a 'transferred LoP. It's analagous to a DR or air position's relationship to a pinpoint. You can use a couple of these + a 'proper' line of position to give you a fix. Quite handy if there is only a single navaid somewhere to the left or right of track since it enables you to get a fix.
You would get a line of position while the aid was ahead & to the side of your track, then a second LoP when you were abeam it then a 3rd LoP when it's behind & to the side.
Transfer (hence the name) the first two LoPs using known or estimated TMG & G/S over the time from taking each of them to when the 3rd LOP was done. Where they cross is where you are. If they don't cross exactly (usual case) then you're in the middle of the 'cocked hat' triangle they form. If TMG &/or G/S isn't known then use HDG &/or TAS.
Some people (erm.....like me
) love navigation. You may or may not want to go into such detail. Nevertheless it all adds up to helping get from A to B since you can choose the best method for the various conditions.
Hope your flight goes well.
T.
** Fold your chart so that there is still a decent amount showing to the L & right of track and beyond your destination. Large features in those areas are useful for basic orientation.
** Make sure you're comfortable with some form of track correction calculation. This could be 1:60 (my preference), pre-drawn drift lines or whatever.
I like 1:60 because it's so flexible. It can be done in your head very quickly to an acceptable accuracy by memorising about 4 numbers:
If the distance run (or to run) is anywhere 60 nm then multiply the distance off track by 1 to get Track Error or Closing Angle. eg 57 miles since last fix. 5 miles off track = 5 deg TE. 68 nm to desired on track position = another 5 deg. Total HDG change = 10 deg.
If ~30 nm run/to run, multiply dist. off track by 2. eg 35 nm run, 3 off = 6 deg TE
If ~20 then x3
If ~15 then x4
If ~45 then x 1.5 --> this is an interpolation but good enough. After all, the whole of the 1:60 method is based on approximations!
If 120 nm then dist. off x a half.
** A fix or DR position isn't proven until the next anticipated fix occurs.
** Use a navigation log. That's a key part of navigating to somewhere that's unknown.
It doesn't have to be on some sort of form. Your map itself makes a very good log device. That's what I use.
Use the correct nav. symbols on your chart to remind you later in the flight about what sort of fix or position line you were able to get earlier. This helps tell you how much you can rely on that particular 'fix'/DR position.
Important things are Times, Headings & Groundspeed. TAS too if you're varying it a lot.
The common symbols include:
A dot with a little circle around it: a pinpoint ie you can prove you're over that position. Still subject to my earlier comment though
.A dot with a little square around it: This is an AIR position ie where you would be having held HDG & TAS for xx mins. There is no wind effect in this.
If you add wind effect for that period time then you get:
A dot with a little triangle around it: this is a DR position ie where you THINK you are based on calculation eg have held xx HDG for yy mins @ zz TAS with this much wind effect therefore I should be 'here'.
A line with an arrow at each end: This marks a line of position. You're somewhere on that line. Two of these lines crossing give you a FIX. Use common sense about how long you draw the line.
This next is a bit more complicated & not often used. That said, I've happily used it a number of times before. It's just another tool to add to your box of tricks...
A dotted line with an arrow at each end. This is a 'running line of position' or a 'transferred LoP. It's analagous to a DR or air position's relationship to a pinpoint. You can use a couple of these + a 'proper' line of position to give you a fix. Quite handy if there is only a single navaid somewhere to the left or right of track since it enables you to get a fix.
You would get a line of position while the aid was ahead & to the side of your track, then a second LoP when you were abeam it then a 3rd LoP when it's behind & to the side.
Transfer (hence the name) the first two LoPs using known or estimated TMG & G/S over the time from taking each of them to when the 3rd LOP was done. Where they cross is where you are. If they don't cross exactly (usual case) then you're in the middle of the 'cocked hat' triangle they form. If TMG &/or G/S isn't known then use HDG &/or TAS.
Some people (erm.....like me
) love navigation. You may or may not want to go into such detail. Nevertheless it all adds up to helping get from A to B since you can choose the best method for the various conditions.Hope your flight goes well.
T.
The 1 in 60 rule is based on similar right-angled triangles, but don't let that put you off!
Basically, imagine a long skinny right-angled triangle with the two sides at right angles being 60 units and 1 unit long respectively.
It so happens that the angle formed between the long side and the hypotenuse is 1 degree.
Now make the short side 2 units long; the angle becomes 2 degrees, and so on. This works for smaller angles, say less than about 15 degrees or so.
The similar triangles part goes like this: Using a triangle with long side 60 units and short side 4 units, the angle as described above would be 4 degrees. Say your long side was then 30 units and the short side 2 units, that would still be a 4 degree angle, and so on for all the other similar triangles – long 120, short 8 etc.
In flying terms, it means that if you have drifted 1 mile across track for 60 along, your track angle error is 1 degree. You would use it like this:
Say you departed on track overhead an airfield and flew your planned heading (let’s say 090). If the wind was exactly as forecast, you should stay right on track.
You take a pinpoint after 40 miles along track and find you’re 2 miles left of track.
2 in 40 is the same as 3 in 60 (just using the same proportion) or 3 degrees, so you have actually made good a track 3 degrees to the left of your planned track.
To parallel your planned track, you would turn right 3 degrees onto 093.
However, you’re still 2 miles left of track. To get back to track, you use the 1 in 60 rule again.
From the ‘parallel track heading’, you want to change heading further right to go back to track, and it depends on how quickly you want to get back as to how big a change you make.
To get back on in 60 miles, 2 in 60 is 2 degrees, so turn right a further 2 deg onto 095.
To get back on in 30 miles, 2 in 30 is 4 in 60, so turn 4 degrees further, onto 097.
You can pick any distance you like – if there was a good feature on track in 37 miles, I’d say something like this to myself – 37 is very close to 40. 2 in 40 equals 3 in 60, so I’ll turn right 3 degrees more from the parallel track heading, onto 096.
That’s basically it – do a bunch of practice ones of these on paper using different distances flown, miles off track, and distance to go to get back on track. Very useful once you get the hang of it; happy mental DR-ing.
PS Gaunty, 90 kts is about my speed these days, not that I ever went that quick previously – only ever had a joyride in those fast pointy things...
Basically, imagine a long skinny right-angled triangle with the two sides at right angles being 60 units and 1 unit long respectively.
It so happens that the angle formed between the long side and the hypotenuse is 1 degree.
Now make the short side 2 units long; the angle becomes 2 degrees, and so on. This works for smaller angles, say less than about 15 degrees or so.
The similar triangles part goes like this: Using a triangle with long side 60 units and short side 4 units, the angle as described above would be 4 degrees. Say your long side was then 30 units and the short side 2 units, that would still be a 4 degree angle, and so on for all the other similar triangles – long 120, short 8 etc.
In flying terms, it means that if you have drifted 1 mile across track for 60 along, your track angle error is 1 degree. You would use it like this:
Say you departed on track overhead an airfield and flew your planned heading (let’s say 090). If the wind was exactly as forecast, you should stay right on track.
You take a pinpoint after 40 miles along track and find you’re 2 miles left of track.
2 in 40 is the same as 3 in 60 (just using the same proportion) or 3 degrees, so you have actually made good a track 3 degrees to the left of your planned track.
To parallel your planned track, you would turn right 3 degrees onto 093.
However, you’re still 2 miles left of track. To get back to track, you use the 1 in 60 rule again.
From the ‘parallel track heading’, you want to change heading further right to go back to track, and it depends on how quickly you want to get back as to how big a change you make.
To get back on in 60 miles, 2 in 60 is 2 degrees, so turn right a further 2 deg onto 095.
To get back on in 30 miles, 2 in 30 is 4 in 60, so turn 4 degrees further, onto 097.
You can pick any distance you like – if there was a good feature on track in 37 miles, I’d say something like this to myself – 37 is very close to 40. 2 in 40 equals 3 in 60, so I’ll turn right 3 degrees more from the parallel track heading, onto 096.
That’s basically it – do a bunch of practice ones of these on paper using different distances flown, miles off track, and distance to go to get back on track. Very useful once you get the hang of it; happy mental DR-ing.
PS Gaunty, 90 kts is about my speed these days, not that I ever went that quick previously – only ever had a joyride in those fast pointy things...
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Ascend Charlie's method is not only good for a chopper, it works well in any aeroplane when you are stuck low down below cloud if you do a bit of preflight preparation with your chart. It's really just a variation on a theme long used by mariners when in coastal areas.
Look for features on your chart along track that may be lined up, e.g. a small lake with a prominent hill or small town behind it, and also look for features that will line up to form these so-called 'transit' lines cutting across your track at 30 to 90 degree angles. Rule them in on your chart in pencil so that they cross each other. Not too many as you don't want to get confused, just obvious ones or ones you hope will be obvious. Where transits intersect is exactly where you are and even if you can't get them to line up conveniently with your track, you will soon get the idea that any transit, if properly identified, is as accurate as any radio-aid derived line of position.
Don't panic if you occasionally can't see what you expect once in the air - some features on WAC charts just don't show up too well.
Keep ticking off the 10nm marks as well, and if you miss one, just keep the DR going.
Also, the advice to build in a deliberate offset is good, but take into account the sun - you don't want to be looking into the sun for your destination.
Look for features on your chart along track that may be lined up, e.g. a small lake with a prominent hill or small town behind it, and also look for features that will line up to form these so-called 'transit' lines cutting across your track at 30 to 90 degree angles. Rule them in on your chart in pencil so that they cross each other. Not too many as you don't want to get confused, just obvious ones or ones you hope will be obvious. Where transits intersect is exactly where you are and even if you can't get them to line up conveniently with your track, you will soon get the idea that any transit, if properly identified, is as accurate as any radio-aid derived line of position.
Don't panic if you occasionally can't see what you expect once in the air - some features on WAC charts just don't show up too well.
Keep ticking off the 10nm marks as well, and if you miss one, just keep the DR going.
Also, the advice to build in a deliberate offset is good, but take into account the sun - you don't want to be looking into the sun for your destination.
just to pick up on some ones comment above re wind direction.
Be very careful there, don't jump to conclusions. Looking at smoke is only useful in determining wind direction if you are down low.
Using cloud shadows is only useful in determining wind direction if you are around the level of the cloud.
The wind can and does change direction very quickly with altitude at times. An example is dry season in the territory, strong easterly wind on the ground and by the time you get to 10,000 ft it can be a strong westerly !
Be very careful there, don't jump to conclusions. Looking at smoke is only useful in determining wind direction if you are down low.
Using cloud shadows is only useful in determining wind direction if you are around the level of the cloud.
The wind can and does change direction very quickly with altitude at times. An example is dry season in the territory, strong easterly wind on the ground and by the time you get to 10,000 ft it can be a strong westerly !
