This hollow rubber canister was used in the late 1930s to provide airmail service to areas without adequate airport facilities. The right design was critical as the canister, filled with mail, would be tossed out of the airplane to be retrieved and processed by the local postmaster. Because a regular mail sack would be easily blown about by the wind, a weighted holder was needed. However, too heavy a canister might cause significant damage if it hit something when it fell. In addition, the canister had to be able to survive repeated drops. Various different styles of receptacles were tested. The proponents of the service ultimately selected this design, resembling the nose cone of a rocket.
The service was not operated by the Post Office Department but by an independently operated aviation company, All American Airways (AAA). The first airmail pick-up mail exchange was made on May 12, 1939. The service never moved out of the experimental stage. It was used on airmail routes in Ohio, New York, Pennsylvania, Kentucky, and West Virginia. In all, more than 150 post offices were served. The experimental routes covered 1,040 miles. During the first year of operation, more than 23,000 pick-ups were made, amounting to 75,000 pounds of mail. The service was used in those areas for about ten years.
The plane first used was a single engine Stinson aircraft, which was capable of speeds reaching approximately 150 miles an hour. On the ground, the postmaster loaded the town's mail into a container, which was then placed on top of a contraption resembling a goal post.
The airplane's crew consisted of the pilot and a flight officer who worked the pick-up mechanism, making the mail exchange. As the pilot guided the airplane down, the flight officer lowered a grappling hook to snag the container. At the same time, mail destined for the community was dropped from the plane onto the airfield. The technique was modeled on the Railway Mail Service's 'mail-on-the-fly' pickups.
Although a low-flying airplane could easily dump a sack of mail onto the ground, the difficult part was getting ground mail into the moving airplane. The Railway Mail Service's successful 'on-the-fly' mail exchange system provided the inspiration for an aviation experiment. Mail would be 'caught' by an airplane flying overhead and reeled up into the airplane. Of course, catching the mail was not going to be easy. An airplane outfitted with a hook flew over the posts and successfully hooked the mail and reeled it in. At the top of each pole was a small direction flag, which showed the pilot the prevailing wind direction, and a pincer, which was used to keep the sixty-foot-long noose attached to the mail canister in place.