Ab Initio 49: “Lines in the Sky”

In which I lament the intractable nature of January weather, and fly around for an hour trying to figure out where I am with the aid of invisible electro-magical wizardy.

Atrocious visibility inland and to the east meant that the planned Wolverhampton-Gloucester nav-ex was off again but it seemed a shame to waste the calm, hazy sunshine that south Wales itself had managed.

Today’s Plan B was to do a bit more with radio navigation aids and do some position fixing using them. We went over the procedures on the whiteboard then it was out to the aeroplane. Wrangling chart, ruler, protractor, and pens things promised to be a lot more of a handful in the air than on the ground but for now I lobbed them all in the back while I got on with the checks.

New set of things to remember about setting up the frequencies for the nav aids, not made any simpler by the fact that the two school Tomahawks are equipped quite differently! Keith, my instructor today, suggested making a habit of writing down the Morse for the “indents” of the aids we wanted to use. Although there’s a key on the edge of the chart, it’s a bit of a feat to unfold it far enough to read while in flight!

We took off in a slight south-easterly crosswind and climbed into the circuit. We departed from the downwind leg and kept climbing as we turned north towards Carmarthen. As I’d discovered in the previous lesson the Brecon and Strumble VORs are not conveniently placed to get a good cut in our usual area so we planned to head west and use the NDB at Aberporth for one of our position lines.

First task was to tune and identify the Strumble VOR. This required turning the dial until the needle reached the middle. This was not quite as simple as it sounds as it invariably (or invariably when I did it anyway!) overshot and required increasing small alterations to get it in the middle. Once in the middle and with the FROM flag showing it tells you what radial (or bearing) you’re on from the station. You then draw that on that chart. This generally requires taking both hands on the controls if you want your line to be anywhere near accurate.

Not for long of course and you make sure that the aeroplane is nicely trimmed first, but even so, “Letting go of the aeroplane” is not something of which I’m especially fond to be honest. Even on those occasions I’ve actually managed to get it properly trimmed there’s something odd about it. Perhaps it’s because it’s one of the things so different in flying compared to travelling on the ground–you can’t imagine the driver letting go of a car steering wheel to consult the A-Z after all!

In spite of my misgivings, the aeroplane behaved as it should and didn’t decide to try and make a break for freedom or take up aerobatics while my attention was elsewhere for a few seconds.

One line done. Now hurry up and do the other before we get too far away from this one! Another things about navigating in aeroplanes–no layby to pull over into while you consult that A-Z again!

For the second line we were using the Aberporth NDB, so again it was a case of tune it, identify it, then try to interpret what it was telling you. The ADF is quite a different presentation to the VOR and the method we were using requiring first aligning our heading with the top of the dial. With that done, the head of needle would read the bearing to the station and the tail would read the bearing from it, which was the information we needed to plot our second line.

Unlike the VORs there’s no handy compass rose on the NDBs marked on the chart so this required fishing for the protractor before letting go of the aeroplane again, quickly drawing another line, and allowing a little bit for distance move while fiddling around! X marks the spot where the lines cross.

So where are we?

Over a completely featureless bit of west Wales countryside. Brill.

We’ll have to take this one on faith…

In fact, about a minute or so later a village, (hopefully Trelech) did appear in about the right place.

We were a goodly distance towards Haverfordwest now and the bank of cloud that had been in the distance was now directly ahead and getting rapidly closer. It was well below us but we wanted to keep contact with the ground so turned back to the northwest. Quite a striking weather feature, the edge of the cloud layer was very well defined.

Back to Brecon VOR and another cut with the Aberporth NDB gave us the same problem as with Brecon and Strumble, we were almost on a straight line between them and “temporarily uncertain of position.

Another cut with Strumble and Aberporth put us somewhere between Newcastle Emlyn and Llanybydder which were nice and easy to spot.

Then it was time to head back. “Where’s the airfield from here?”

Quick cast about for a heading, which I guess at around 190 degrees.

Almost home, the DME suddenly decided to start working and we did the easiest fix of the day by finding the radial from Brecon and reading the distance from it off the DME.

In spite of the sunshine, the haze was very apparent now and I was glad it was an area I had come to know reasonably well. There’s a lot to be said for coastal airfields–the sun on the water, glinting through the haze, was the best nav-aid of all!

A Shadow microlight was returning at the same time as us and uncertain of being able to spot him we stayed up above the ATZ and descended out over the sea while he made his overhead join. It made for a pretty view of Cefn Sidan too!

My approach was frankly appalling. For the first time in goodness know how long I’m actually out of practice at crosswinds and completely failed to allow for the tailwind on base leg. Matters were made worse by my join being rather too close in, resulting in me being too high and well off the centreline after overshooting the turn to final. The actual touchdown wasn’t too bad, but still a rather embarrassing mess!

All cured by the post-flying steak sandwich! Everyone still at the airfield piled down the pub, to the ‘flying corner’ in the Butchers’ Arms, with the pictures of aeroplanes on the walls and comfy sofas!

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