On a serious note let's not forget that a major cause of the world's worst air disaster at Tenerife was ambiguous r/t calls.
An excellent point Mike. FWIW, the details were slightly different. There were only the two aircraft around at the time. The controller gave the KLM aircraft, lined up on the runway, its airways clearance, containing the words "after take-off" It was this that was misunderstood as a take-off clearance. It was compounded by some unfortunate crossing of subsequent clarifying transmissions.
Accident account