Deceleration Physics Formulation
The total net stopping force acting on the aircraft at instantaneous velocity v(t) is governed by:
F_net = F_braking(v) + F_aero(v) + F_reverser(v) + F_emas(x)
Where F_braking = μ(v) × (Mass × g - Lift(v)). Ground spoiler deployment dumps wing lift, transferring 85%+ of aircraft weight onto wheels to prevent hydroplaning skids.
Dynamic Hydroplaning Limit
According to NASA and FAA equations, the minimum dynamic hydroplaning speed on ungrooved standing water is modeled as:
V_p = 9 × √(Tire Pressure in PSI)
For a widebody jet tire pressurized to 200 PSI, V_p ≈ 127 knots. Above this threshold on flooded pavement, a water wedge completely lifts the tire off asphalt, reducing braking friction μ to near zero.
How EMAS Saves Lives
An Engineered Materials Arrestor System (EMAS) is placed at the runway departure threshold. Constructed from cellular lightweight concrete blocks with tailored compressive strength, the blocks reliably crush under tire loading, absorbing kinetic energy at up to 1.4 G without inducing severe landing gear shear or passenger trauma.