US FAA accepts that GNSS may fail
The Administration is to hold a public meeting to consider alternative positioning, navigation and timing should satellite services be interrupted.
Currently the FAA's alternative positioning, navigation and timing (APNT) uses a variety of non-GNSS equipment, including distance measuring equipment (DME), VHF omnidirectional range (VOR), instrument landing system (ILS) and radar surveillance.
But the agency admits that - with the coming of its space-based next generation air transport system (NextGen) - these 'legacy' systems will not provide the minimum level of APNT performance required.
Hence it is collecting information regarding R&D and potential implementation of systems and procedures that would minimise the impact of 'periods of GNSS interference'.
An enhanced version of Loran (eLoran) has been proposed by the US National Space-Based PNT Advisory Board as an APNT, but this has been subject to political in-fighting within the US - and the current Loran-C in the US and Canada is being shut-down this year.
And Airbus and Boeing are reported to believe that the flight management and inertial measurement systems (FMS & IMS) in their modern aircraft can provide enough performance in the event of a GNSS outage - negating the need for an independent back-up.
The current 11-year solar sun-spot cycle is due to peak in mid-2013 (see NASA link below) - with warnings that it could be very disruptive to GNSS (GPS, GLONASS and possibly Galileo by then).
The FAA 3-day public meeting will be held in August in Stanford, California.