  This paper presents a Markov chain model to dynamically emulate the effects
of adverse (failure) flight conditions on fixed-wing, autonomous aircraft
system actuators. It implements a PX4 Autopilot flight stack module that
perturbs the attitude control inputs to the plane's actuator mixer. We apply
this approach in simulation on a fixed-wing autonomous aircraft to test the
controller response to stochastic compound failures on a range of turning
radii. Statistical measures of the differences between target and simulated
flight paths demonstrate that a well-tuned PID controller remains competitive
with adaptive control in a cascading, compound, transient failure regime.
