Todd Smith wrote.........
The radio is quicker and easier. The issue about miss identified.........

I'm with you 100% Todd, There was an instructor at Minden who is no
longer with us because of no radio communications. After calling for
the sailplane to close his spoilers, the tow pilot gave the signal
(rudder wag) which was mis-understood and the sailplane released at
300 feet, made a 180 degree turn and hit the wires at the end of 30.
Student severely injured and instructor later died from complications
relating to the accident. The radio should be the primary means of
communications and the tow should not be initiated without a com
check. Joe would be with us today if he had followed this procedure.
JJ