“Zero-zero” is the ultimate goal of any so-called all weather program. Weather histories at several major airports in the U.S. are analyzed to determine how much gain may be expected with achievement of 100-1/4 minimums, and finally “zero-zero.” The cost of lost revenue due to diversions is compared with the cost of today's radio equipment. Estimates of future costs are made, and the resulting curve extrapolated to determine the point of maximum economic gain during the pursuit of lower weather minimums. The philosophy of instrument approach operation is discussed.
A study is made of the development of United Air Lines' present instrument approach practices, and is combined with certain facts and opinions of the author to show that there are two answers to the “zero-zero” problem: automatic landing or a “real world” instrument presentation. The various advantages and disadvantages of each solution are discussed, with the conclusion that the attainment of minimums below the safe go-around altitude of the particular airplane involved will require a fundamental change in the instrumentation provided to the flight crew.