Methods to Ventilate a Jet

• Pilot keeps one engine running in order to provide some power to the aircraft’s own vent system
• The airline purchase ground auxiliary carts. These units are connected to the aircrafts own ventilation duct to infuse clean air at the gate.
• Electrical power is supplied from the gate to the aircraft in order to operate the aircrafts system
• Flight crew keep the front door open as long as possible and hope convection draws air to the rear of the aircraft.

In the current era of constrained resources, all of these methods take either time, money, or labor. None of which the airlines want to expend.