This paper gives details of the failure rates and the failure modes
experienced with SPS GPS
receivers certificated for aviation use to the TSO-C129 specification.
These failure rates are
significant compared to those from other modern avionics and the rates
are comparable to that
currently experienced from un-scheduled failures in the GPS
signals-in-space. To achieve
certification, Flight Management System (FMS) design
should consider the way in which the
satellite navigation receivers fail. The paper also gives details
concerning the 2-D errors that
have been experienced with these receivers, and indicates further work
that needs to be done
with C 129a receivers.