General Rule: VS ≈ Ground Speed × (Glide Slope Angle°) × 1.75
Exact Formula: VS = Ground Speed × tan(angle) × 101.3
Standard Slopes: ILS = 3°, PAPI = 3-3.5°, Tactical = Variable
Examples: 3° → GS×5, 6° → GS×10.5, 9° → GS×15.75