There was no radio aids during my flight training. We simply telephoned the control tower of the school and told them which plane was about to take off. I could fly by myself because I had the license, and the only procedure was this: I called them, they said “okay”, and I taxied to the runway just to wait for the green light. They did, of course, tell you beforehand which runway you were departing from, but once you flew off they left you all alone. An hour later I flew back to the control tower to let them know I was done, and they would put on the yellow light for my preparation. After that, if the green light was on I could land straight ahead; if it was a red light, I had to fly away. We were qualified to fly alone, and there were very few planes at that time. It’s better we did it around 5 o’clock in the morning or at night. We telephoned the control tower, and a green light meant “go”, a yellow light meant “get set”, a red light meant “clear off”, that is, we had to wait for the runway to become available.