Map reading in featureless terrain
A VFR flight crosses a large area of uniform farmland with few roads. The pilot's last confirmed fix was 25 minutes ago. Since then, a forecast 20 kt tailwind component has become a 15 kt headwind, and the pilot has been holding a constant heading. The planned route passes a lake 12 nm to the left of track, but the pilot now sees a lake ahead and slightly right. Visibility is 20 km, the sun is high, and the GPS is showing a position that disagrees with the pilot's dead-reckoning estimate by 9 nm. The aircraft has 2 hours of fuel remaining.
1. Explain why the visual and dead-reckoning positions might disagree, and how to resolve the conflict.
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A constant heading with a changed wind produces drift the pilot has not corrected: the forecast tailwind became a headwind, and any crosswind component will have pushed the aircraft off track progressively. Over 25 minutes at, say, 110 kt, that is about 46 nm flown, so even a 10° drift gives roughly 8 nm of lateral error - consistent with a 9 nm discrepancy. The lake ahead-right may therefore be the planned lake seen from an unexpected angle, or a different lake entirely.
The resolution is to treat the GPS as one source and the visual picture as another, then seek independent confirmation: identify a unique feature (lake shape, road junction, settlement pattern), compare it with the chart, and cross-check with a second navaid or the GPS track and ground speed. Do not simply accept the GPS and abandon map reading, and do not ignore a persistent 9 nm offset.
2. If the position remains uncertain after 5 more minutes, what lost procedure should the pilot follow?
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The pilot should climb (terrain and airspace permitting) to widen the field of view and improve radio and navaid reception, then apply a systematic lost procedure: hold a steady heading and note the time, draw a line of position from any identifiable feature, obtain a bearing from a VOR or ADF if available and plot it, and compare with the GPS. If still uncertain, turn toward a large known feature such as the coast, a major road, or a town, and follow it to a known point.
With 2 hours of fuel, the pilot has time, but should set a decision point: if a positive fix is not obtained within, say, 20 minutes, declare an emergency or divert to the nearest suitable airfield. The judgement tested is methodical re-establishment of position rather than random wandering, and recognising when to stop searching and ask for help.