Bizarre symbols written in ‘invisible paint’ on the undercarriage of several Southwest Airline’s planes are being investigated by the FBI.
The writing – which only shows up with heat – appears to be Arabic script.
The special chemical paint appears towards the back of the 737 aircraft, but only after an auxiliary power unit on the plane is turned on, warming the underbelly, engines and landing gear.
Most of the affected planes appear to be flying out of Los Angeles.
In a statement to KNX 1070 radio, Southwest said it is working with authorities to uncover who was behind the ‘vandalism’, but added that currently it is not clear how many people are involved.
Southwest also said the writings did not imply any safety issues.
Despite an FBI investigation into the writings, the trend has increased in recent weeks.
You can read the full report from the UK’s Daily Mail here.