Don't do that — Page 233, Lesson 216

I want to walk you through what happens when you, as a navigator, become uncertain of your position. This is a situation every pilot will face at some point, and the natural temptation is to just carry on and hope for the best. Don't do that. The moment you realise you're uncertain, you need to start immediately trying to resolve it using every aid available to you. This is a critical phase of flight. One of the biggest dangers here is that pilots over-concentrate on the navigation problem and forget to check their fuel and aircraft systems. So your very first step is to check your fuel and aircraft systems. Once that's done, you follow a structured 'lost' procedure. Let me walk you through that procedure step by step. First, check your compass and airspeed indicator to make sure you are actually flying the planned headings and speeds. If you've drifted off without realising it, correcting that might solve the problem immediately. Second, if meteorological conditions and airspace restrictions allow it, climb. Climbing increases your visual horizon and your radio horizon, giving you a better chance of picking up a fix or seeing a landmark. Third, fix your position using all aids available. That means VOR/DME, VDF (which is VHF Direction Finding), a radar fix, or a visual fix. Use whatever you have. Fourth, if you are restricted to purely visual methods — map reading — then you calculate a DR position. DR stands for 'Deduced Reckoning', though it's commonly known as 'Dead Reckoning'. This is a calculated estimate of where you are. Fifth, that DR position should be deduced using the position and time of your last known accurate fix, combined with the track, ground speed, and time flown since that fix. So you take where you definitely were, and you project forward based on what you've been doing since then. Sixth, you draw a 'circle of uncertainty' around that DR position. The circle is normally drawn with a radius of 10% of the distance flown since the last fix. So if you've flown 100 nautical miles since your last fix, your circle of uncertainty has a radius of 10 nautical miles. Remember that the DR position continues to move along track, and the circle of uncertainty gets larger with time. Now you map-read from ground to map — that means you look at the ground, find a large visual feature, and locate the aircraft on the map with reference to that feature. On most occasions, your actual aircraft position should lie within that circle of uncertainty. Seventh, if you are still in difficulty, consider turning towards a good visual line feature that lies outside the circle of uncertainty. Examples include a coastline, a motorway, or a main railway line. Once you reach that line feature, turn and follow it until you find a definite visual checkpoint from which proper navigation can be resumed. Now, throughout all of this, you must be careful. Do not fly towards high ground in poor weather below safety altitude. Do not fly into controlled airspace without clearance. Always keep a good lookout, monitor your fuel and aircraft systems, and remember that you can use the Emergency Fixing Service on 121.5 MHz with a PAN call. That is your structured lost procedure — a disciplined, step-by-step approach to resolving uncertainty without letting the situation escalate.