Barr, R. Armstrong, T.R. Arrell, S. 1993 The use of a GPS aircraft (RNZAF C130) as a mobile platform to study the propagation of Omega navigation signals. Proceedings of the 18th Annual Meeting of the International Omega Association, Orlando, Florida, October.
Barr, R. Armstrong, T.R. Arrell, S. 1994 Small scale anomalies in Omega position data revealed with GPS. Proceedings of the 1994 Technical Meeting of ‘The Institute of Navigation’, San Diego, California.
Barr, R. Armstrong, T.R. Arrell, S. 1994 The use of GPS equipped aircraft as a mobile platform to study the propagation of Omega navigation signals. Journal of the Royal Institute of Navigation 47: 221-235
Barr, R. 1995 A simple theoretical model for computing omega navigation errors near Antarctica. Journal of atmospheric and terrestrial physics 57(8): 961-966