Abstract: Methods and apparatus for predicting airfoil stall for an aircraft having a control surface. Measurements of forces or moments acting upon an integrated span of the control surface are sensed over a period of time to provided unsteady data. The unsteady data is filtered to remove structural frequencies and input to at least one stall warning detection function, and an output is received. Each of the stall warning detection functions identifies an angle-of-attack that is approximately within a predetermined number of degrees of stall when the received output reaches a threshold. The received output is compared to the threshold to determine whether an angle-of-attack exists that is near stall.

Abstract: A method and system for sensing surface contamination on an aircraft having a control surface. A control element including the control surface is connected to the aircraft by a hinge. The method and system sense a control surface hinge moment about a line on the hinge of the aircraft. A control surface steady hinge moment coefficient is calculated from control surface hinge moment data representing the hinge moment over a period of time. An unsteady hinge moment is calculated which is dependent on the control surface steady hinge moment coefficient. By using a value which is relatively constant during uncontaminated surface conditions, this value can be compared against calculated values to check for variations. If the calculated unsteady value varies from the known uncontaminated values, a warning may be given, alerting an operator of unsafe conditions. This warning is given before a critical value is reached, allowing the operator a period of time to react to the warning.