Redundancy in engine timing position sensing maintains a UAV operational in the event of failure of a primary engine timing position sub-system. The redundancy avoids duplication of the primary crankshaft timing position sensing components, and avoids adding weight, cost and component complexity. Conditioned (square) waveform(s) (102) is/are created from respective sinusoidal waveform(s). Each consecutive leading edge (103a) and trailing edge (103b) of the pulses of the square waveform (102) is derived from the crossing of the zero voltage value by consecutive sinusoidal waveforms A,B,C (e.g. Voltage (V) vs Time (t) or angular degrees). The square pulse waveform (102) is output (104) to a microcontroller (106) to create and output a pseudo crankshaft timing position signal (108) to be used by an ECU to determine ignition and fuel injection events in the event that the primary timing signal from the crankshaft position sensor (CPS) has failed. The signal (108) output to the ECU can have a missing pulse (116) (i.e. indicative of a TDC position of the engine crankshaft) as well as multiple square pulses (114) corresponding to the pulses of the initial square pulse waveform (102). The waveform signal (108) is therefore derived from the alternator waveform signal(s) and provides a pseudo crankshaft timing position signal in the event of failure of the primary or initial CPS signal.