A method for de-icing liquid on a surface of an airplane includes supplying de-icing liquid to and through a spraying nozzle of a de-icing vehicle through a pipe that connects the nozzle with a tank assembly of the de-icing vehicle, where the liquid is delivered to the spraying nozzle as a mix of an anti-freeze liquid and additives, the anti-freeze liquid is delivered to the pipe from an anti-freeze liquid tank via a first dosage pump, and the additives are delivered from an additives tank via a second dosage pump.