Lost on the Way In
You are on a VFR flight in Class G airspace, navigating by map, compass, and timing, with a handheld GPS as backup. The GPS has just failed and will not restart. You are 25 min from your planned destination, a controlled airport with a Class D tower. You are not certain of your position: you can see a town below and a river, but there are two towns of similar size on the map within 20 km of each other, and the river bends in a way that matches both. You have a VOR receiver and a heading indicator, and the destination VOR is within range. Fuel is comfortable but not unlimited, and the cloud base is lowering.
1. What is the most reliable way to fix your position with the equipment you have, and how would you confirm it?
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Use the VOR: tune the destination VOR, identify it by Morse, centre the needle with a FROM indication, and read the radial. That gives a line from the VOR on which you lie. To fix a point on that line, take a second bearing - from another VOR if in range, or a visual bearing to a known landmark (the town or a distinctive river bend) using the DI. Alternatively, use the VOR radial plus the DME distance if available, which gives a direct fix. Confirm by checking that the fix is consistent with your heading, time flown, and the landmarks you can see. If the two candidate towns are both on the same radial, the radial alone will not resolve them - you need the second line of position or the DME distance.
2. If you cannot confirm your position, what should you do next, and what should you tell ATC?
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If the fix remains uncertain, do not press on into controlled airspace. Climb if conditions allow to improve radio and visual range, and call the destination tower or approach on the published frequency: state that you are a VFR aircraft, give your last confirmed position and time, your heading and altitude, and that you are uncertain of position. Ask for a bearing or a vector, or for radar identification. ATC can give you a bearing or confirm your position; that is exactly what the service is for. If you cannot establish two-way radio contact, remain clear of the Class D and follow the lost-procedure actions: fly a steady heading and altitude, note the time, and use the VOR to work the problem. Do not enter controlled airspace without a clearance.
3. What does the lowering cloud base add to the decision, and how does it change your options?
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A lowering base reduces your visual options and increases the risk of inadvertent VMC into IMC, especially if you climb to improve radio range. It also reduces the time available to resolve the navigation problem before you are forced to divert or descend. That argues for resolving the position quickly: get the VOR fix, call ATC, and if the base continues to lower, divert to an airfield in better conditions rather than continue toward a destination you cannot positively identify. The cloud base is a time limit on the problem - set a decision point (e.g. 10 min) after which, if not positively fixed, you divert. Continuing without a fix in lowering cloud is how VFR flights end up in IMC.