There's actually a lot involved with the de-icing process: "..the spraying procedure is a regimented, step-by-step process. Pilots first follow a checklist to

There's actually a lot involved with the de-icing process: "..the spraying procedure is a regimented, step-by-step process. Pilots first follow a checklist to ensure their plane is correctly configured. Usually the flaps and slats will be lowered to the takeoff position, with the APU providing power and the main engines shut down. The air-conditioning units will be switched off to keep the cabin free of fumes. When deicing is complete, the ground crew tells the pilots which types of fluid were used, as well as the exact time that treatment began. This allows us to keep track of something called a “holdover time.” If the holdover time is exceeded before the plane has a chance to take off, a second round of spraying may be required. The length of the holdover depends on the kind of fluids used, plus the rate and type of active precipitation (dry snow, wet snow, ice pellets; light, moderate, heavy). We have charts to figure it all out." https://askthepilot.com/snow-ice-and-airplanes/ https://askthepilot.com/snow-ice-and-airplanes/