DR Navigiation

[Tango Oscar]

Yesterday, I did my first solo nav ex. I was a little apprehensive before the flight, as I have been experiencing some difficulty navigating, using the map and DR. The first two legs(of a four legged sortie) went fine, and I found my way points. However, I started to go a little adrift after that. I think I found my third way point, and eventually found my fourth point by using a radial from the VOR at my local airfield.

I know the theory of time, map, ground, and have recently passed the navigation exam. My problem is I seem to have real difficulty matching what is on the ground, to what is on the map. Has anyone else had and overcome this problem ? This is the only part of the PPL course which has caused me any trouble, and it is really denting my confidence.

Any advice would be greatly appreciated.

[FlyingForFun]

T.O.

Congrats on your first solo nav ex! :D

First of all, don't worry that much about what's on the ground. As long as you fly accurate headings and reasonably accurate speeds, you will be in roughly the right place.

Having said that, you do need to check what's on the ground from time to time. How often will depend on how accurately you can fly, and how strong the wind is (and therefore how wrong the forecast is likely to have been), but every 10 minutes or so should be enough.

Different people have different ways of doing this. Some people like to make 1/2-way and 1/4-way marks on their route. I prefer to use 6-minute marks. But many people seem to be under the misapprehension that these marks determine where and when to check for ground references - this is not true. You should check for ground references wherever there are easy references to check for!

For example, if you're passing a large town, that would make a great reference point. If you were using the 6-minute mark system, you might notice your town is about 1/3 of the way between the 2nd and 3rd marks, i.e. about 14 minutes into the leg. It doesn't matter that it's not actually on one of the marks!

Good things to look for are towns, big road junctions, masts, chalk figures on the ground, large airfields, lakes..... Things you should be careful of are rivers (except for the biggest rivers) and railways, which are difficult to spot from the air, and small villages, because you'll often find villages not marked on your chart which will confuse you.

Once you think you've identified your landmark, verify. Check the roads come out of a town in the direction you expect them to. Check the town is roughly the correct shape and size. Check it's in the correct position relative to other towns that you can see. If you're using an airfield, make sure the runways have the correct orientation. (You might even be able to check the runway numbers - but you'll probably want to be quite high over an airfield, so this might not be an option.) Railways and rivers can be good verification points, even though they're not good landmarks.

Don't worry if you miss a landmark - just carry on to the next landmark. Sometimes you look at something on the chart, and it seems like it should be easy to spot, but you can't tell until you actually get there - it might turn out to be invisible from the air. Check your heading and airspeed, and if they're right and you can't see the landmark, the chances are you're in the right place, but you just missed it. Just carry on to the next landmark. However, start making notes of your exact heading/airspeed and the time that you make any heading changes, as well as anything you notice on the ground, whether you can tie it to something on the chart or not. If you miss two landmarks in a row, and decide that you've become temporarilly uncertain of your position, you'll find these notes will help you rationally work out the area that you're likely to be in.

Finally, use your experience from yesterday positively. Did you eventually manage to figure out where you actually were before you were unable to find your fourth waypoint using DR? If not, go back to the chart and find out. A few months ago, I was uncertain of my position. I eventually got back to somewhere I recognised. After the flight, I tried to analyze what went wrong. I figured that I must have been at the more southerly of two large lakes, when I thought I was at the more northerly of the two. I was still uncertain of how I managed to get to the wrong lake, but I was pretty sure that's what had happened. Shortly afterwards, I went back to the same place again, and realised that the more northerly of the first lakes had dried up - that's what had confused me. If you can figure out what you did right and what you did wrong yesterday, you won't make the same mistakes again. And you've also learnt how to use a VOR as a backup, which should be a big confidence boost for you.

Well done!

FFF
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[QNH 1013]

FFF's comprehensive reply leaves little room for anything to be added, but I would add:
Power Stations - usually on a river - make very good landmarks. They appear on the maps as multiple ^^^. They can be seen from further away than any other landmark in my opinion. FFF points out that railway lines aren't always too useful, but I find railway junctions make good references.

VRPs sometimes are very hard to identify which seemed very odd to me when I started flying. I suppose when they were first put on the maps they were prominent features, but sometimes time and development obliterates them. However, they still stay on the maps.

Finally, there is an great deal of detail on the 1:500,000 charts if you study them and this helps a lot with identification. e.g. make sure you know the symbol for a multi-level road junction as these tend to stand out.
Good luck, sounds as if you're doing fine.

[Tango Oscar]

FFF / 1013

Thanks for taking the time to reply, and the advice. Tonight, I will study the map again, and try to decide exactly where I was, before I had to resort to using the VOR.

I think some of the problem may have been because of the time difference between completing my plog, and actually beginning the flight. The aeroplane was late arriving, and needed refueling. I then wasn't allowed in the circuit, for a couple of T & G's first, because of the volume of inbound traffic(coming in from Le touquet I think). Ultimately, there was 3.5 hours gap, and I think the wind dropped considerably in that time. If that happens again, I'll redo the plog.

Regardless of the above, I know there is plenty of room for improvement in my map reading, and I will try to take on board your comments/advice. My next lesson is a solo landaway, if my nerves can handle it, so wish me luck.

T.O.

:eek:

[englishal]

Know what you mean about matching the map to the ground, everything looks much smaller from up there!....which is why I went and got an IR, suddenly everything becomes SO much easier !

Cheers
EA:D

[logie_bear]

Not much to add other than to congratulate FFF on a great response.

Nice refresher for those of us in need of refreshing!

Ta,
l_b

[timzsta]

Congrats on your first solo nav ex. You cant have done that bad as you obviously made it home to tell us of your experience. Be cautious using power stations as check points though - post Sep 11 many have 2 mile exclusion zones around them, so check the NOTAMs first before choosing one for nav. Happy landings.

[Who has control?]

Well Done Tango Oscar! IMHO the first solo navex is a bigger step than first solo.

The only thing that i would add to the excellent advice already posted is - look at maps. Some people find maps as easy to read, to others (Mrs WHC) they are a closed book. Learn your local area - the 4Rs - Roads, Railways, Rivers and Reservoirs.

I have a great deal of respect for pilots in the Midlands, for down here, we are rarely far from the biggest landmark of all - the coast.

[Whirlybird]

Navigation is like many things; the more you do it the easier it gets. Practise, practise, practise. Try to remember the size and distance of things at different altitudes. Try and remember your local area.

Don't get disheartened, it takes a while - longer for some people than others. I got lost on my second solo cross country, and very lost on a relatively long trip soon after getting my PPL. Don't worry; it happens to us all. It only sounds easy in theory; it isn't. But it will get better.

[drum]

Tango oscar,

You were able to find your airfield and that is the most important.
I have my licence now for a few months and it is sometimes still difficult to find what I see on the map. Since a few weeks I have frequently flown with a fellow who has about the same hours as me. We agree who will fly to our destination and who from. I enjoy it very much when it is my turn to fly but when my fellow is flying I have the time to do one thing; navigate. In those moments, my skills improves very much. The small details that can help you to find your way which you don't see when your are flying seems than so easy to find. As low hour, you are often busy with flying and you miss that small details that can certainly help you. Once you are more comfortable with all your instruments and flying will be easier, I am sure your skills to navigate will improve. But meanwhile, find someone who wants to fly with you so that you can discover that sort of spots on the ground and the map that can help you.