A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Ed Popko
Date: 2018 Jun 1, 05:29 -0700
My father flew with Pan American Airways in the 30s and 40s aboard Clippers and smaller seaplanes as a radio operator. Mostly his routes were out of Dinner Key (Miami, FL) to various Caribbean Island and northern South American ports.
His main job was communicating, via Morse Code, to PAA's weather stations along the way. There was a 'half-way' rule. If the weather had changed and was not acceptable at the destination when the plane was at the half-way point, they plane returned home or diverted to another convenient stop over. This was particularly important during the hurricane season when the weather was so variable. Radio operators communicated with any other planes in the area as well though the sky was not as crowded as it is today. Operators also sent back weather reports as the flight progressed.
PAA was a pioneer in many forms of long-haul over-water navigation and land-fall techniques. Those planes equipped with RDF equipment would get bearings to their weather stations or public broadcast stations at or near their destination. Every operator kept a list of high-powered AM ground stations, their call sign and frequencies to hone in on. In the picture you atached, It's possible that one of the operators is doing double-duty and helping the navigator with RDF bearings though the photo does not include any view of a device for changing a loop antenna. In the 30's its too early for automatic honing.
Unlike today, flying in the 30's was a luxary for well-off folks. When you see photos of passengers boarding seaplanes or in-flight, you see them well dressed and well tended to. On some routes, PAA offered message service to passengers and one of the radio operators in the photo may be doing that. Messages were usually to business associates or well wishers. Radio operators had a small reference book of simple short-form codes, usually four numbers, that substituted for common phrases, greetings, salutations or the headers and footers for standard messages such as weather or position reports. For confidential or special business messages, there were criptographic codes as well.
As ships neared their destination, radio operators exchanged messages with 'ground' operations as to landing conditions or special needs. For landing, wind strength, direction and water conditions such as chop or tide were key. In exceptional conditions, a late arriving flights near dusk, would request 'runway' lights, long strings of float-lights called 'pearls', to mark a runway on the water. Dusk or 'night' landings were rare and to be avoided. Even with pearls, it's near impossible to judge where the plane of the water is for landing. For day arrivals, a beaching crew may be requested, swimmers who attached tires to the sides of the hull so that the plane can be winched out of the water after the passengers are discharged.