Jigsaw Puzzle of H2S Display

By assembling jigsaw puzzles like this one of Oslo Fjord in Norway, RAF navigators learned to recognise places from the way they were displayed on H2S ground mapping radar screens.

At night or through cloud H2S radar revealed the hidden ground below the aircraft. This greatly improved bombing accuracy, but It took practice to be able to read the radar map shown on the H2S screen. Comparing photographs of radar displays with conventional maps of the target area was a good way to learn. Turning these photographs into jigsaw puzzles for navigators to assemble taught them to use H2S with greater skill.