Delhi
Indira Gandhi International (DEL) is the busiest departure point in the country, and Hyderabad is one of the sectors it feeds hardest. One practical detail catches out last-minute DEL flyers more than any other: IGI splits domestic departures across more than one terminal, and moving between them is not a five-minute walk. Read the terminal off your e-ticket before you leave, not after you arrive. December and January fog is the other DEL-specific risk on this sector — early-morning slots are the ones that slip, so if your Hyderabad meeting is fixed, a mid-morning departure buys you margin the 06:00 flight does not.