The Dallas/Fort Worth International Airport Fire Training Research Center trains fire fighters locally, nationally and internationally in the specialty of airport / aircraft fire fighting.
They use many different aircraft-designed mock-ups, and purposely ignite the mock-ups to train these fire fighters. During training periods you will see black smoke as a result of these training fires.
The DFW FTRC uses clean burning propane and a liquid fuel called E-III – both are environmentally friendly.
— DFW Airport (@DFWAirport) September 10, 2018