Test by US Post Office in which plane drops airmail containers over Miami and containers are then delivered through pneumatic tubes

Plane taking off / inside plane two postal clerks sorting mail / VS clerk putting mail into containers to be dropped from plane / VS plane in flight / plane flying low / two containers falling into net on ground, men run up to net / men taking containers out of net / man putting container into pneumatic tube / rows of mail containers in post office / containers come out of pneumatic tube / clerk pouring mail out of containers while others sort mail / Note: exact month/day not known