Three types of self-contained navigation systems may perhaps be found, operating independently on airliners flying polar routes; doppler, astro and inertial. We may also find hybrid systems with doppler, astro and inertial components. The combination of doppler and astro systems should be the first step towards self-contained automatic navigation and this combination could be used with great advantage by the airlines for global operations. The more sophisticated doppler and inertial combination may be found too expensive for airline operators and may therefore be restricted to military uses.