Popham panel
Ground-to-air signaling device
A Popham panel, or T-signalling panel, was a means of ground-to-air communication, in Morse code, developed during the First World War, before the introduction of radio communication. They were named for Robert Brooke-Popham and were used by the British and American armed forces.
They were used in the Waziristan campaign of 1919–1920, and in the Kabul Airlift of 1928, and remained in use as a reserve method of communicating with aircraft as late as just before the Second World War. They were eventually rendered obsolete by the development of effective radio communication with aircraft.
Origin
The Popham panel, first introduced in 1918, was named for First World War Royal Air Force officer, Robert Brooke-Popham, and designed to communicate messages to aircraft from the ground, in Morse code, before the introduction of radio communication.
Operation
Anne Baker described a Popham panel as the size of a "small Persian rug" and structured as a blind. The top of the slats were painted green and from the air, it appeared green when closed. Strong elastic held the slats closed and the operator could pull a cord against the tension of the elastic, to open the blind, showing a white background. The person on the ground could open the panel for a short time, indicating a "dot" in Morse code, or a longer time, indicating a "dash", and thereby had a method of producing a message. If the aircraft located the panel, the air crew could be able to read a message sent by the ground operator.
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This entry incorporates text from “Popham panel” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.