Establishment Criteria for Visual Approach Slope Indicator (VASI).


Book Description

This report develops revised establishment and discontinuance criteria for Visual Approach Slope Indicator (VASI) which provide Visual Flight Rules (VFR) guidance only. Criteria are based upon detailed benefit/cost methodology. This approach takes into account the number of aircraft landings by user class with variations depending upon whether or not the runway is equipped with an Instrument Landing System. Benefits derived from a VASI were principally in the area of safety which are obtained by improved guidance during final VFR approaches. Revised criteria require that a ratio value be computed for each of the three types of operations (air carrier, air taxi, and general aviation including military). The three ratios are then added to obtain a total ratio value, and this is multiplied by the runway utilization to obtain a net ratio value. If this net ratio value is equal to 1 or greater, then the runway is a candidate for a VASI. In the short term, it is estimated that 590 runways now without a VASI will qualify. Over the next ten years, an additional 388 runways are expected to qualify for a VASI. (Author).













Simplified Visual Approach Slope Indicator (VASI).


Book Description

The purpose of this operational test and evaluation was to determine the value of a simplified visual approach slope indicator (VASI) system to the USAF Special Operations Force by accomplishing three test objectives: formulate and document construction criteria, establish user acceptance/rejection, and incorporate an air-transportable capability. Two types of systems were designed and constructed for user evaluation. Both were identical except for the support arrangement. One system was embedded in the ground, and the other was anchored to the ground by using sandbags. Both systems could be transported by air. Two hundred and eighty approaches were flown against the systems by 61 different pilots. The majority of pilots indicated that the systems were effective beginning at distances ranging from 1/2 to 1 mile and ending at 25- to 50-foot altitude (approximately 450 to 950 feet in front of the boards) during night or daytime operation. The best color combination was determined to be black stripe on white background. It was recommended that USAF Special Operations Force retain the two systems for potential future use during deployments to austere bases, temporary airfields, and landing zones not equipped with standard VASI. (Author).