Dec 05

Radio Navigation

I’ve had a long break from flying (not through choice, but due to weather), waiting to try and get my first navigation exercise done. After a cancelled lesson last week, I was advised to read up on the radio navigation side of things, as that was something we could do if the weather was good enough for a flight in to the local area, but not for the nav.

This morning while Cambridge was alright (a little cold, and a fairly large crosswind, but well within limits), it was overcast at 500 feet out where the nav was supposed to be going, so we put this plan in to practise in G-UFCB. The instructor mentioned this wasn’t something they’d done in this order before, but they thought I should be able to handle it.

The take-off and climb out were a little shakey (due to a combination of not having flown for 4 weeks and a gusty wind), but safe enough. Once we got to altitude the instructor gave me a few minutes to practise straight and level to get myself back in to the swing of things. Unfortunately I seem to have remembered my tendency to climb slightly when trying to remain level, which would lead to regular prompting to check my attitude during the flight 🙁

We started off with VORs (VHF Omnidirectional Range) – once tuned and identified, these are used by selecting a specific radial (which can be thought of like a spoke from a bicycle tyre), and you then get an indication of how far away from that radial you are, and whether that radial is going to or from the beacon. They can be used either to fly directly to the beacon, or to ascertain position by determining what radial you are currently on (thus giving you a straight line from the VOR station that you know you are somewhere on). The tricky bit here is adjusting for the effects of wind, something I’ve just about got my head round, but will need more practise I think.

Next up was the DME (Distance Measuring Equipment) – this gives you the slant distance from your present location to the DME station. They’re often co-located with a VOR station, allowing you to therefore get a position fix by determining what radial you’re on, and then the distance you are from the station. We tried doing this, and other than my freehand line drawing skills not really being up to much, it seemed to work.

We then used the GPS, this is essentially the same principal as the GPS you might use in a car, with the difference being it gives you a heading to fly to get to the waypoint rather than telling you what turns to make. We didn’t do very much on this (partly because the GPS in the aircraft seemed a little unreliable), but it all made sense.

As time was getting low (the brief had taken a while, and it had taken a while for the aircraft to warm up etc), we then headed back to Cambridge (we’ll leave the ADF until next time), opting for a right base join. I’ve not done one of these before, and that combined with the fact I’ve not attempted to land an aircraft in 4 weeks meant the instructor was going to talk me through it, and if necessary take control (it was going to be a challenging landing anyway as there was a strong crosswind). I got a bit low during the base leg (I think due to the unfamiliar landmarks giving me little to judge my height from), but after correcting that I managed to get us down without any drama, and without much input from the instructor, which given it was a crosswind that was approaching if not beyond the solo limits I was quite pleased with.

I’ve got another lesson booked tomorrow – in an attempt to increase the chance that I can fly a nav route I’ve been given the second one to plan (which goes in a different direction), so we have a choice of options if it’s still bad out towards one of them…