Over the course of many training articles, I have attempted to give some basic tips on navigation, starting with the fundamentals of heading and airspeed, clock/map/ground, using big-to-small features and the navigation workcycle.
Hopefully the keen students out there have realised that all three must be effectively used in order to successfully navigate around the countryside visually. But what if things go wrong? How can these workcycles help?
A scenario: 15 minutes after your last turn point you begin your preparation for the next leg. However, to your surprise, you realise you misread your map at the last turn point and that the heading that has been flown for the past 15 minutes is 45 degrees in error. (It happens, I have seen students do this and worse!) The first thing to do is…don’t panic. Sit on your hands and make time for you to sort the issue out. Fly the aircraft – by this I mean maintain the heading and airspeed, trim the aircraft out to minimise distractions from flying errors and begin to work out firstly where you are and then how to get back on track.
So, where are you? If you had diligently flown the heading (although the incorrect heading) and the desired airspeed (let’s say 120 knots ground speed) you are able to work out your position on the map quite easily and then relate this to the ground. Look back down your log at your last check/turn point. This is the last known accurate position of the aircraft. Using speed and time you know the aircraft has flown 30 nm in the past 15 minutes. Since you have accurately held the heading, the track from this position can be determined. Trace out on the map the 30 nm distance on the flown track. This point is your best guess or dead reckoning (DR) position. Now, using big features first (mountain ranges, large rivers, the coast for example) on the map begin to pinpoint your position. For example, at your DR position there may be a distinctive peninsula about 5 nm to the north. Look outside and find the peninsula on the ground. Once located, pinpoint using smaller features until the exact position of the aircraft is known.
So you now know where you are. Using the map you are now able to determine how best to regain track. This will involve planning a diversion from some point ahead of the aircraft – this will be covered in later issues.
The important aspect of this scenario is the fact that if the pilot had not flown an accurate airspeed or heading (even though it was the wrong heading), clock/map/ground will not work. Your actual track is impossible to retrace on the map because it was not constant. Further, once lost, I have seen many students panic and blindly attempt to find a recognisable feature out the front of the aircraft and relate that feature to a point on the map. Often this results in the aircraft being flown erratically around the countryside until a suitable feature is chosen and incorrectly identified – the problem then gets worse.
Remember also there are other aspects to being lost – fuel available, airspace restrictions and boundaries are all in the equation. It is important to develop your own ‘lost’ checklist with your instructor which includes all these points. But remember, that checklist is useless unless your fundamental navigation and aircraft handling is sound. Accurate flying creates a known starting point from which heading and airspeed, clock/map/ground and big-to-small can build up your situational awareness of your aircraft’s position.