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Accuracy-aumented GPS, i.e. WAAS and even more emphatically, local area accuracy-augmented GPS, blows everything else away so completely in terms of accuracy, we are in danger of becomming too dependent on it. So we need to keep alternatives on the back-burner. Years ago, microwave landing systems were developed to improve on the accuracy of traditional ILS. But implementation of MLS was halted owing to the availability of GPS, particularly after President Bill Clinton ordered that full GPS accuracy be made available to everybody, not just the military.

Airport Surveillance Radar approaches, whereby the air traffic controller gives the pilot the word as to whether to go left or right, up or down are one answer. But at small airports, where there is no tower and nobody on duty, automated radar approaches would be needed. One can imagine a synthesized voice, sounding masculine or feminine as needed to make the pilot comfortable, giving instructions based on radar at any of a number of wavelengths.

When a plane on a landing approach is close to the ground and the runway, maximum accuracy is called for. So I envision a millimeter wave radar system, operating at ~35 GHz (that’s ~35,000 Megahertz!) or even higher (i.e. 94 GHz), locating the aircraft’s precise position and then an automated system as I described above, vectoring the pilot to the point where hopefully there will be enough optical visibility for him or her to complete the landing manually.

At said frequencies, range is limited owing to atmospheric absorption. So when an aircraft is more than a kilometer or so from the runway, lower frequency radar would be utilized, switching to millimeter wave when the aircraft gets in close enough for accuracy, rather than range, to be most vital.

The last radar approach I had was in the late 50′s at MDW “Chicago”. It was excellant. The controller did a great job, I never had the occasion to do that again during my nearly 18,000 Hours of flight time. My confidence was there in the system if I ever needed it.

I believe it would be worth while and could save lives if our controllers were trained and offered practrice GCA approachs to pilots when time and cercumstances allow.