Navigation

So far, July's focus has been on VFR Navigation. As usual, CTC have detailed procedures for approaching this, which are logical and relatively easy to follow. Some of the skills that we picked up during Ground School have come into play, mostly the use of the whizzwheel to complete the Flight Log or FLOG as it's known and how to interpret the weather forecasts accurately and safely.

The kit required to plan a Navigation route

As we know by 4pm what the next day's schedule will be, it is usually possible to plan the route for the flight the night before and draw this on to the chart. Owing to the terrain around Hamilton and the weather that results from this, it usually makes good sense to plan two routes, one in a NE direction and one in a SW for example. This means you can pick the one on the day that most suits the weather and also allows them to be planned on separate charts so it does not look confusing in the air.

This pre-planning can get as far as measuring the true tracks with a protractor and converting them into magnetic tracks (the variation here at Hamilton is 20 degrees East which means you deduct 20 from your true track - to go directly West for example would be heading 250). You can also measure the distances in Nautical Miles and enter all these details in to the FLOG. That is about all for the night before as everything else is dependent on weather.

The next day can be an early start. Several of my flights have been departing at 7.45/8am which means getting to the airport no later than 6am to get the planning done. Even that is a bit tight so once the daylight hours get longer and we are able to fly earlier, there will be times of getting up at unbelievable o'clock in the morning and doing as much planning at home as possible using the morning's forecast on the internet.

Once at the training centre, you can get the wind speed and direction at the altitude you will be flying, generally around the 3000' level around here. We can go higher, and indeed do to avoid terrain sometimes, but unless you've got a completely clear sky, 3000' is usually about the best you can hope for in order to remain clear of cloud. The airspace is arranged a bit like an upside-down wedding cake in NZ with upper limits for uncontrolled airspace being around 2500' in the vicinity of a controlled airfield to 6500' or more on cross country routes. Wind direction is given in degrees true, so again needs to be converted to magnetic in order to be applied to the tracks to calculate a magnetic heading. In simple terms, if you are heading on the 250 track mentioned earlier but have a southerly wind blowing towards you, you will need to direct the aircraft towards the left to accommodate the resulting drift. A relatively strong wind could mean a magnetic heading of 240 in that case for example.

The windspeed will also have an effect. If you are flying straight into a 20 knot headwind, then the 108kt true airspeed of the aircraft will be 88 knots. A crosswind will have less of an effect on speed but a greater effect on heading etc.

So once all this is factored in, you can begin to calculate timings. These are crucial as you use features on the ground (known as Event Cycle Features) and turning points to know where you should be at certain times. If you can see your event cycle feature coming up ahead of you but your stopwatch says you should already be there, then you can be confident that you have a stronger headwind component than you thought and adjust the FLOG's groundspeed for that leg and the subsequent timings accordingly. 

So while most of this planning is done on the ground, weather forecasts are seldom perfect and will need revision in the air en route. This is all very well in calm conditions, but attempting to battle even moderate turbulence while updating the FLOG, calculating new timings and headings etc can be very challenging. The greatest challenge is often to plan an inflight diversion when it becomes clear that the conditions ahead are going to be outside the scope of VFR flight. As this more often than not makes the flying itself more difficult, there are various quick estimates that can be used for headings and speeds based on 'clock codes' to get the diversion done swiftly and safely before conditions get any worse. The new heading can then be refined once established.

We have also incorporated some Instrument Flight, as described in my last post, into this with the instructor confirming the position of the aircraft visually while the cadet flies accurately using only the instruments. This includes flight into the Control Zone of an aerodrome not visited before, in my case Tauranga, which when combined with some horrendous turbulence made for the most challenging flight that I've had out here.

While all this sounds as if I might be quite experienced at it, the reality is that the weather here has been terrible for most of July so we are now well behind schedule on the flights we should have achieved by this point. I have cancelled the same flight five times this week already and don't see any signs of being able to achieve it any time soon. Each low pressure system with its rain and wind is followed by a high pressure system of fog and poor visibility. So we are all looking forward to August when we should start to see the very first signs of Spring and some improvements in the weather! On a more positive note, from a tourist's point of view there have been some fairly wonderful sunsets and sunrises which have made things a little more interesting:

 Early morning at the training centre

 Early morning at Clearways 

(I think the name is supposed to be ironic - Fogways would be better)

In other news, my hobby out here has been playing Tenor Horn in Hamilton City Brass. The band went to the National Championships in New Plymouth this weekend and I am delighted to say that we won our category! The only downside was the weather preventing us from seeing Mount Taranaki in its full glory: