[Hoverbug]

Originally Posted by Blackdog_kt

A lot of things are possible, but unless you're flying as a dedicated navigator you probably won't use most of it. It's not wrong, it's just not practical enough.

Whenever i dabble into stuff like that, i never do trigonometry. If i need to fly perpendicular to the beacon to obtain a distance fix, then it's clear i'm going off course to get a fix. Much better and faster to tune a second beacon and see where the lines intersect on the map, presto, you have a precise fix of your position.

Even if your plane doesn't have a second nav radio and a second ADF, you can tune the first beacon and draw the line, then tune the second one and do the same on your single radio. Unless you are very close to the beacon (where the bearing changes fast), it will be accurate enough.

There's lots of quick and dirty methods that give you enough accuracy without having to go all mathematical about it. For me, being able to obtain an accuracy equal to the visual range is good enough. For example, if the visibility at my current altitude and weather conditions is 10 miles, i won't mind at all if my radio navigation gives me a 5 mile error margin (it's actually lower than that most of the times, think 2-3 miles). And if flying at night, most aircraft that historically did it were better equipped to deal with it.

Tuning 2 beacons and getting the respective bearings can also help you determine wind drift. See where the bearing lines cross and that's your position, wait (the 3m 15sec rule from silent hunter is good here) and get a new fix. Connect them on the map and it you used a 3m15s interval, the amount of kms travelled times 10 will give you your ground speed in knots. For example, if you've travelled 10km then your ground speed is 100 knots. Compare the heading of the line connecting the two fixes on the map with your actuall compass readout and you can also see the amount of wind drift involved.

Some aircraft might also have specialized equipment. In B17 the mighty 8th, the navigator had a scope that looked down towards the ground. It had some continuous horizontal lines running across the scope view, as well as dotted lines that could be rotated. The idea was to rotate the dotted line lens until the view seemed to be moving without any drift (it's been a few years, don't remember it exactly), then you could read out the drift from the markings on the wheel that turned the dotted lines.

I remember my instrument instructor teaching me how to do a DME arc without a DME using a similar procedure. By flying at a standard speed (e.g. 90 kts), one could easily calculate distance by flying at 90 degrees to the VOR and by seeing how long it took between 10 degree increments of radials. Not something I ever used again though.