A departure control system (DCS) is the software that runs the airport side of a flight: check-in, seat changes, bag tags and the boarding scan. It is part of the airline's passenger service system (PSS). The check-in agent's screen, the self-service kiosk and the scanner at the boarding gate all use the DCS.
The DCS opens a flight for check-in, often 48 hours before departure for web check-in. From then on, it records who has checked in, who sits in which seat and which bags are going into the hold. Each checked bag gets a tag with a barcode and a 10-digit number. Some airlines and airports also use RFID tags on bags. A reader can detect an RFID tag without seeing it, so fewer bags are lost.
Say a morning flight from Pune to Bengaluru has 180 seats and 176 bookings. By 5:30 a.m., 168 passengers have checked in, most of them on the airline's app. At the counter, a passenger's bag weighs 17 kg. Her fare allows 15 kg, so the DCS calculates an excess baggage charge for 2 kg and prints the bag tag after she pays. At the gate, an agent scans each boarding pass. The DCS checks that the pass is for this flight and that the passenger has not boarded already. Boarding closes 20 minutes before departure. Four passengers have not come, and the DCS marks them as no-shows. It also finds that one of them checked in a bag. That bag must be taken off the aircraft, because a bag may not fly without its owner.
Before departure, the DCS sends the final figures to the airline's load control team: 172 passengers, their seats and the weight of their bags. The team uses these figures to check the aircraft's weight and balance, which must be within limits for take-off. The same figures tell the ground staff how many bags to load. Bags and cargo are loaded with ground support equipment, such as belt loaders. Cargo carried in the same hold is recorded in the air cargo community system.
A DCS problem stops flights at once. If the DCS fails, staff must check passengers in by hand, and every flight is delayed. At many Indian airports, passengers can also enter the terminal and board by a face scan, using digital travel credentials.