G-AWFL was a UNIT Aérospatiale SA 318C Alouette II helicopter, used by the Third Doctor and the Brigadier during the giant insect crisis. It was equipped with riot gas. (COMIC: Insect)
As G-AWFL, it was used by Carrington's men to attack a UNIT convoy, (TV: The Ambassadors of Death), and presumably acquired afterwards by UNIT for their own use.