On 12 Apr, 11:15, Don Johnstone wrote:
If you go back far enough the stop light was a red light, this was fine
until it was remembered that there is no requirement for colour blindness
testing for glider pilots, let alone winch drivers. The only real problem
with lights only is the confusion between a long dash and the stop signal.

I think there are worse problems - mainly the need for the person
pressing the button to know (a) what signal he is trying to give and
(b) how the light system reacts to the button being pressed.

Talking of blindness, though, I used to get launched by a blind winch
driver - or at least by one whose eyesight was so bad that he
certainly couldn't see the cable and could barely see the glider.
"Exciting" was one word for it.

Ian