The RAF intercepted coded messages between airline pilots discussing the plans for the attacks in the week following last year’s Paris attacks. The Arabic transcripts were then passed to GCHQ where intelligence operatives established that they were talking about carrying out attacks on London, Bath, Brighton and Ipswich. The pro-ISIS pilots were discovered using an emergency channel in the belief it was not being monitored however that was exactly what the RAF were doing.
It is believed that the pilots were preparing to smuggle in bombs or chemical weapons from the Middle East and either deliver them to ISIS supporters in the UK or carry out the attacks themselves possibly using their airliners. The discovery of the plot raised the terror alert in the UK and the Army has now launched Operation: Templer which involves up 10,000 soldiers being deployed to support British law enforcement and emergency services in the UK.
The aircraft were flying from Amsterdam to the Middle East and therefore no effort was made to intercept the aircraft. Contact with the pilots have been lost but their voice samples are now on file allowing intelligence services to identify them if they try to enter UK airspace. Their identities have also been put on a watch list for terror suspects and their airline has now been listed as having known ISIS sympathizers in their ranks.