Pre-flight Planning and Weather Assessment
The planning loop
Pre-flight planning is a decision process, not a paperwork ritual. Work through it in a fixed order so nothing is skipped: route and airspace, then weather, then aircraft serviceability and performance, then fuel and mass, then ATS filing. Each step can veto the ones after it, so a late weather check that invalidates your fuel plan wastes less time than the reverse.
Weather products you must read fluently
Know the difference between a forecast and an observation, and the validity period and issue times of each product. Be able to extract from a TAF the expected wind, visibility, cloud and significant weather for your ETA window, and to compare that against your planning minima. METAR and trend forecasts give the current state; area forecasts and significant weather charts give the en-route picture. Know how to read freezing level, tropopause height, jet stream position and the likelihood of icing or embedded convection. A candidate must understand pressure altitude versus density altitude and how QNH and temperature combine to change both.
Traps
Questions frequently hinge on timing: a TAF issued before your departure may not cover your arrival, so you need an alternate or a later forecast. Watch for minima that are stated as ceiling and visibility combined, and for the difference between alternate minima and destination minima. Another common trap is treating a PROB30 group as a certainty, or ignoring a TEMPO group because it is brief.
Rule of thumb
For a rough crosswind check, take the angle between wind and runway: at 30 degrees use half the wind speed, at 45 degrees about 0.7, at 60 degrees about 0.9. For density altitude, add roughly 120 ft per degree Celsius above ISA.