The trick: On a flooded runway a tyre can lift off the surface and skim like a speedboat. Dynamic hydroplaning speed V_HP (knots) = 9 × √(tyre pressure in PSI).

• Find √PSI   • Multiply by 9   • Answer in knots

Worked example: Tyre pressure 36 PSI → √36 = 6 → 9 × 6 = 54 kt. Above 54 kt on standing water, that tyre is hydroplaning.

How to play. Each round is 12 questions. Start in CADET mode — just the square roots, no nines yet. When the roots feel automatic, move to PILOT for the full V_HP calculation on typical light-aircraft tyres. When the trick is second nature, fly TOWER — airliner-pressure tyres against the clock, with a bonus for the heavy stuff. Beat the top 10 and you'll be invited to add your callsign to the global leaderboard.