Snow and bitter cold gripped Denver International Airport and others across the country Friday, putting its winter weather response plan to the first big test of the season.As of 8p.m., there were 608 delays and 36 cancellations at DEN, according to flighttracking service FlightAware.Airport spokeswoman Ashley Forest said while DEN is no stranger to cold weather or snow, Fridays frigid conditions and the predicted deep freeze for the weekend mean extra caution and extra work on the airfield.Its the same process, Forest said of the snow response. The only difference is we increase measures to make sure runways and taxiways are cleared. And we make sure those working outside, like baggage and ramp crews, can come inside to warm up. The airlines do that too its about keeping everyone safe in these temperatures. Cold and snow is disrupting flights at Denver International AirportEven in heavy snowfall, Forest said runway crews can clear and reopen a surface for takeoff in an average of 13 to 17 minutes.Deicing, required for every plane in subzero conditions, can add another 10 to 15 minutes before departure.The airports extensive snow equipment updated last year is staged to keep runways, taxiways, and roadways passable.Heating systems, including HVAC and boilers, are checked and maintained to handle extreme temperatures.Our crews have been ready since last summer, Forest said. Theyve been here since last night and this morning, making sure the airport is running, that everything is functioning, ready to plow the roads and clear the runways. The biggest stress is for passengers to be safe, first and foremost.Forest noted that while DEN can handle severe weather, delay and cancellation decisions rest with airlines, and national weather patterns can ripple into Denvers schedule.Airport staffing is increased for storms, with contingency plans for more personnel, especially if overnight weather is anticipated.For travelers, Forest offered this advice: Check with airlines for the latest flight information before leaving home ideally two to four hours before departure and plan to arrive at least two hours early to navigate parking, TSA screening, and gate access. ...read more read less