Abstract :
This paper was presented at the G-AES Luncheon, NAECON 1970, Dayton, Ohio, May 19, 1970, where Mr. Hansel received the 1970 Pioneer Award (see page 721 of the September 1970 issue of this TRANSACTIONS). The author offers some personal obserivations on the challenge of compatibility in systems planninig with special reference to civil aviation He discusses VOR accuracy and RF spectrum utilization as typical compatibility problems and also as particularly timely and important challenges to planners who seek compatible evolution toward higher performance goals and efficient use of an important and limited natural resource. He notes several lessons to be learned about the challenge of compatibility in systems planning. 1) Major improvements of mature systems can be accomplished with minimum compatibility impact only if we plan and act boldly and early and with a long range perspective. 2) Many years are required to implement a major change in the fixed plant portion of a large system. This gives us time to introduce design changes in newly manufactured subscriber equipments long before any practicable deadline for full system implementation. By deadline time the relatively few older unchanged subscriber equipments still in service will be a minor fraction of the total in service. These remaining older equipments can then either be used without benefit of higher performance, or can be retrofitted or replaced at a cost which is an acceptable price for essential progress. 3) We have an often unrecognized obligation to the future as we plan both new systems and improvements and extensions of existing systems. This is the obligation to plan, from the outset, for progressive evolutionary compatibility, not only with existing equipments, but also with future performance requirements and with efficient use of the RF spectrum. 4) Near term compatibility requirements need not be and must not be permitted to become a deadening and stagnating constraint on future progress.
