Effects which normally diminish the value of a manually flown instrument approach are examined in the light of flight test results with the Head-Up Display (HUD). It is possible to avoid shortsightedness (space myopia) and disorientation phenomena associated with poor external visibility, by choice of display position and format, allowing an efficient alternation between display and forward view. The display can also be designed to fit the man, in both static and dynamic characteristics, with benefits of rapid learning and accurate tracking.
These results remove the basis for supposing man's intervention in the all-weather landing to be disastrous. On the other hand, man's participation may be necessary, because more information is connected with a safe approach than can be dealt with by an unaided machine. Synthesis of an automatic system with HUD may turn out to be the most acceptable solution to the overall problem of all-weather operation.