Airplane Landing Performance on Contaminated Runways in Adverse Conditions

A realistic analysis of operational landing and stopping performance of large-transport-category airplanes on contaminated runways in adverse conditions is presented. A new mathematical model of landing flare is introduced. Heaviside step functions were employed to model the time-delayed deployment of ground spoilers, brakes, and thrust reversers and to account for variations in pilot techniques. A simulation model, based on submodels for each landing phase, consists of several distinct systems of simultaneous nonlinear coupled ordinary differential equations, semi-empirical models, and many accompanying algebraic relationships for aerodynamic coefficients and other parameters. The fall nonlinear differential model was solved numerically using the simple Heun's predictor-corrector method. Different landing scenarios were simulated to obtain realistic stopping distances as well as the time histories of deceleration and speed. The model accounts for many contaminated runway scenarios, hydroplaning, the effect of wind, the speed-dependent rolling-friction coefficient, and other important parameters. We have presented landing scenarios using average pilot techniques on ice-covered runways for which the Federal Aviation Administration wet-runway safety factor is not sufficient for a safe landing. This mathematical model and the simulation program can be used as an operational landing distance calculator. A sensitivity analysis was performed to estimate the significance of various parameters with the absolute maximum landing distance uncertainty estimated to be 100 ft.