Things students reliably get wrong:
- Light arcs: wing nav lights show through 110°, the tail light through 70°. Green is starboard, red is port. "Red to red is safe."
- Right-of-way order: balloon > glider > airship > powered. Powered gives way to everything, and everyone gives way to an aircraft towing.
- Head-on: both turn right (not just one).
- VFR low-level Class G: at/below 3,000 ft, ≤140 kt, by day → 1,500 m, clear of cloud, in sight of surface (the table's default is 5 km; 1,500 m is the speed/traffic concession).
- The 8 km / 5 km split: 8 km visibility at or above FL100, 5 km below it.
- Transition altitude is 3,000 ft in most of the UK (18,000 ft in the USA, don't import it).
- High to low, beware below applies to falling temperature as well as falling pressure.
- QFE vs QNH: QFE → height above the aerodrome; QNH → altitude above MSL.
- Oxygen: crew above 10,000 ft for >30 min, or any time above 13,000 ft; passengers above 13,000 ft.
- 90-day rule: 3 take-offs and landings to carry passengers; at least one at night to carry them at night.
- Class 2 medical: validity 60 / 24 / 12 months for ages <40 / 40–49 / ≥50, truncated at 42 and 51.
- Steady red light in flight = continue circling, do not land (not "stop", that's the on-ground meaning).
- Transponder: 75 hijack, 76 radio fail, 77 emergency, 7000 conspicuity.
- Notification-delay figure: 45 min (aerodrome) and 30 min (SAR), read the question's context.
- Empty mass includes unusable fuel and undrainable oil but excludes usable fuel, drainable oil and the crew.