Comparative Evaluation of Australian TVG and Untited States Standard Visual Approach Slope Indicators

Flight tests were conducted to compare the Australian "Tee" Visual Approach Slope Indicator with the United States Standard "Red-White" Visual Approach Slope Indicator, gathering data to be used for determining whether or not the Australian "Tee" System should replace the United States Standard System. Both systems were installed to serve Runway 13 at the National Aviation Facilities Experimental Center, and were adjusted so that the approach slope angles coincided with the ILS glide path angle.

A significant majority of the pilots preferred the Australian "Tee" System. Phototheodolite recordings showed that the "Tee" System provided more precise and accurate guidance than the "Red-White" System. Pilot comments indicated, however, that the "Tee" System did not provide a satisfactory undershoot indication and that a failure of the fly-up or fly-down units of the system may not be recognized. Pilots also noted that the base leg guidance of the "Tee" System was inferior to the "Red-White" System.

Alignment of the "Tee" System components was more critical than those of the "Red-White" System

Recommendations were made for further development of the "Tee" System and that an evaluation of the improved system be conducted.