Sir - In "FAA concern over military GPS control resurfaces" (Flight International, 11-17 June, P16) it was reported that the US Federal Aviation Administration is concerned about military control of the global-positioning system (GPS) - which is to be its primary means of navigation.
The GPS is also rapidly becoming the navigation or positioning aid of first choice in many land and marine applications, and is already indispensable.
The statement by the vice-chief of the US Air Force Space Command, Lt Gen Patrick Caruana, that it "-fully intends to sustain the GPS constellation" cannot give any guarantee of the standard of service beyond the tenure of the present US Administration.
In the long term, the political situation cannot be predicted. Control of the world's primary navigation aid by the military services of a single nation is clearly unacceptable.
It is surely essential that a satellite and ground-control system should be established under international auspices and with joint funding - perhaps on the lines of spaceflight organisation Inmarsat. This would also supply an opportunity to provide a constellation of more than 24 satellites, so as to give full coverage and adequate redundancy against satellite failure - which the present system does not have. This would reduce, or eliminate, the need for a wide-area augmentation system.
Agreement between nations to set up such a system would require much negotiation, but the first step must be to convince the appropriate authorities.
A H Thomas
Epsom, Surrey, UK
Source: Flight International