Popham panel

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.

[4] They were used during the Waziristan campaign of 1919–20 on the North-West Frontier of India along with the simpler ground-based signals, but military historian Herman Watteville described them as "of no great value" in that fast-moving conflict.

[1] The slow transmission rate was also a problem when aircraft had limited fuel and had to circle for a prolonged period of time to read the more complicated messages, running the risk of having to make an emergency landing in hostile territory.

[5][6] In his book he gave an account of how one bored base commander laboriously signalled to a pilot as a joke that he wanted the actress Mae West rather than the more usual supplies, and got into a great deal of trouble for doing so.

[2][8] The complete panel was eventually delivered to the legation by the Afghan Army, after the aircraft had to land nearby due to damage.