Target indicator

After their introduction, the use of TIs expanded to include en-route markers to gather up lost aircraft, additional TI drops to keep the target lit over long periods, and various changes in technique to address German defences.

Most widely used were the H2S ground scanning radar and Oboe navigation system, the former requiring considerable training to be useful, the latter able to guide only a single aircraft at a time.

8 Group RAF) and having them drop TIs, the accurate fixes could be used to guide the entire attack.

Marking of targets was carried out using the following methods: The three code words were initially chosen by asking three Bomber Command personnel in the operations room where they came from.

The first TIs were converted 4,000 lb (1,800 kg) "cookie" bomb casings filled with red pyrotechnic, benzole, rubber and phosphorus.