The advance of MEMS-based inertial sensors successfully expands their applications to small unmanned
aerial vehicles (UAV), thus resulting in the challenge of reliable and accurate in-flight alignment for airborne
MEMS-based inertial navigation system (INS). In order to strengthen the rapid response capability
for UAVs, this paper proposes a robust in-flight alignment scheme for airborne MEMS-INS aided by global
navigation satellite system (GNSS). Aggravated by noisy MEMS sensors and complicated flight dynamics,
a rotation-vector-based attitude determination method is devised to tackle the in-flight coarse alignment
problem, and the technique of innovation-based robust Kalman filtering is used to handle the adverse impacts
of measurement outliers in GNSS solutions. The results of flight test have indicated that the proposed
alignment approach can accomplish accurate and reliable in-flight alignment in cases of measurement outliers,
which has a significant performance improvement compared with its traditional counterparts.