Flights are cancelled in Dallas due to inclement weather, mechanical issues, or air traffic control delays. Adverse weather events, such as severe thunderstorms, snow, or high winds can cause flights to be delayed or come to a complete stop. Mechanical issues, including broken plane parts and computer malfunctions, can also lead to flight cancellations. Finally, air traffic control delays can prevent flights from taking off and landing in a timely manner. All of these internal and external factors can ultimately lead to flights being cancelled in Dallas.