226SECKEL, ELLIS, AND OLCOTT J. AIRCRAFT same time. This is the case with the decelerating technique at VDEC approach speed. 5) With the decelerating technique, the penalties in difficulty of control and landing distance caused by either excess speed or steep angles are very slight. In the experiment, typical landing distances varied from a little over 600 ft at 7 = 3° to a little under 1000 ft at 7 = 18°. 6) In VFR conditions, as the approach path angle is steepened, the difficulty of the landing gradually increases. Larger rates of descent, higher flare point and increased flare normal acceleration are the contributing factors. Under IFR conditions, these factors would probably severely limit the minimum ceilings that would be operational.NASA, working with American Airlines, has completed the first phase of research to evaluate the operational feasibility of two-segment approaches for noise abatement. For these tests, area navigation was used to establish the upper glide slope and an ILS was used to establish the lower. The flight director was modified to provide command information during the entire approach. Twenty-eight pilots representing the airlines, professional pilot associations, FAA, and NASA participated. With an ILS approach for comparison, the procedure gave a noise reduction of 18 EPNdb at the outer marker and 8 EPNdb 1.1 naut miles from touchdown.

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