How a Flight Happens

Before anyone boards

A flight starts hours before passengers arrive. Dispatchers and the crew prepare a flight plan: route, altitude, fuel load, alternate airports in case of diversion, and a weather briefing. They check NOTAMs (Notices to Air Missions) for anything unusual along the route — closed runways, GPS outages, restricted airspace. In most parts of the world the flight plan isn't just a formality — the dispatcher and the captain share legal responsibility for releasing the flight, and either one can refuse to go if the fuel, weather, or routing doesn't add up. The aircraft itself goes through a pre-flight inspection, and ground crews begin loading baggage, cargo, catering and fuel. The amount of fuel loaded is a deliberate trade-off: carrying more than needed adds weight and burns extra fuel just to carry itself, so dispatchers calculate a specific figure covering the planned route, required reserves, and the alternate airport, rather than simply filling the tanks.

Check-in and boarding

Passengers check in (online, at a kiosk, or at a counter), drop bags if needed, and clear security. At the gate, boarding usually happens in groups — priority passengers first, then by zone or row — to keep the cabin loading efficient. The goal is to have everyone seated with the door closed at the scheduled departure time, even if the aircraft doesn't move until a few minutes later. Airlines typically close the boarding door a set number of minutes before scheduled departure — often 10 to 15 minutes for short-haul flights — since even a fully boarded aircraft still needs the door closed, the boarding bridge or stairs removed, and paperwork finalized before pushback can begin.

Pushback and taxi

Most aircraft can't reverse under their own power at the gate, so a tow vehicle pushes back the aircraft onto the taxiway. From there the pilots taxi to the runway using engine power alone, following instructions from ground control. This is also when the flight attendants complete the safety demonstration and the cabin is secured for departure.

Following the script: SIDs and STARs

Departing and arriving aircraft don't just fly wherever they like near a busy airport — they follow published routes. A Standard Instrument Departure (SID) is a predefined path that gets an aircraft from the runway up into the en-route airspace structure, with specific turns, altitudes, and sometimes speed limits built in. On arrival, a Standard Terminal Arrival Route (STAR) does the reverse, guiding the aircraft from cruise down toward the airport in an orderly way. Both exist to reduce radio chatter and pilot workload: instead of air traffic control issuing dozens of individual instructions, the crew loads the named procedure into the flight management computer and flies it with only occasional adjustments from controllers.

Takeoff and climb

Once cleared by air traffic control, the aircraft lines up on the runway and takes off. The climb to cruising altitude is the phase requiring the most engine power and fuel per minute of any part of the flight. Pilots typically climb in stages — sometimes called step climbs — leveling off temporarily at an intermediate altitude while air traffic control clears the airspace above, since other aircraft may already occupy the altitude the flight is ultimately headed for.

Cruise

This is the longest phase on most flights — level flight at a stable altitude (commonly 30,000–40,000 ft for jet aircraft), where fuel burn per mile is at its most efficient. Air traffic control hands the flight off between different control centers as it crosses regions, each one managing a slice of airspace along the route. On long-haul routes that cross oceans or remote terrain far from any airport, twin-engine aircraft must be certified under rules known as ETOPS (Extended-range Twin-engine Operational Performance Standards), which set how far the aircraft is allowed to fly from a suitable diversion airport in case one engine fails. Throughout cruise, the crew monitors weather, fuel burn against the flight plan, and the schedule, and can request a different altitude or a route change if conditions warrant it. As fuel burns off during a long flight the aircraft gets lighter, which lets it cruise efficiently at a higher altitude than it started at; on long-haul flights, crews sometimes request a step up to a higher cruising level partway through the flight for exactly this reason.

Descent, approach and landing

Descent begins well before the destination — often 100+ nautical miles out — so the aircraft arrives at the right altitude and speed for approach, following a STAR much like the SID it departed on. Air traffic control sequences arriving aircraft, sometimes requiring a holding pattern — a racetrack-shaped loop flown at a fixed altitude — if the airport is busier than the arrival rate can absorb. If conditions at the destination become unsafe or unworkable, such as a runway closure or fuel running low while waiting, the crew can divert to the alternate airport named in the original flight plan rather than continuing to wait. On approach, the crew configures flaps and landing gear, and the aircraft lines up with the runway for landing.

Taxi-in and turnaround

After landing, the aircraft taxis to its gate or stand. From here, the whole process starts again for the next flight — this is the turnaround, covered in its own chapter. A short-haul aircraft might be back in the air within 30–45 minutes of arriving.