Taxi out to the runway
Once the aircraft is boarded with passengers, loaded with cargo and all doors closed, the pilots will obtain a ground clearance from the airport control tower to taxi. The aircraft is then pushed back, typically with a tug. When the aircraft is clear to power under its own steam, the tug is unhooked and the aircraft will taxi (manoeuvre) to the take off runway. The average fuel burn is approximately 25 kg/minute for an A330.
When the aircraft accelerates to a flying speed that is particular to every flight, it becomes airborne and the landing gear is retracted. The actual take off speed and distance required for every flight varies due to a number of factors: pressure height, wind speed and direction, aircraft weight, air temperature, flap setting, runway gradient, clearance and operational requirements.
An aircraft needs a lot of power to take off, and therefore, in normal operational conditions, a power setting close to maximum thrust will be set for take-off. However, like a car engine, jet engines burn more fuel and wear out quicker when working at maximum revs, so the pilots will reduce from take-off power to a lesser thrust for a climb when a safe altitude is deemed to have been reached. (This often causes some concern to passengers as they hear the engines reduce their noise output, and often they will feel the aircraft slow down or even feel as though it is falling out of the sky). The wheels are retracted as soon as the aircraft is airborne to reduce drag and help lift the airplane.
Climb to cruise altitude
About five minutes into the climb (longer if experiencing low level turbulence), the pax (passenger) seatbelt sign is turned off in smooth conditions. This is the cue for cabin crew to be able to unbuckle their seat belts and commence the inflight service.
This is where the bulk of the flight is spent. Optimum cruise altitude depends upon the weight of the aircraft, and typically, an aircraft will ascend (climb) as the flight progresses and fuel weight is burnt off. While it depends on the wind at altitude, it is more fuel efficient to fly as high as we can for as long as we can. The typical cruise level for an A330 ranges from 38,000 ft to 40,000ft.
The descent phase is the decrease in altitude from cruise altitude to initial approach altitude. This is approximately 20 minutes from our estimated time of arrival (ETA). At approximately 7 minutes before landing, the seat belt sign will be turned on by the pilots, which enables the cabin crew to do a ‘final secure’ of the cabin for landing.
At this time, the aircraft has to be configured for landing, and this is predominately predetermined at the flight planning stage. The aircraft will gradually slow down, the flaps at the rear of the wings and the slats at the front of the wing will be extended to create more lift at a slower speed, which ultimately lowers our landing speed. The wheels will be lowered and the aircraft will line up on what they call ‘final’ and continue down the approach path and land.
This is the critical stage of flight where the aircraft slows to such an extent that it literally falls out of the sky just inches from the ground. The landing speed is different for every flight and is dependent on the same factors as for take-off. The aircraft will deploy spoilers on top of the wings to break the smooth airflow over the wings and destroy any ‘lift’ component. They are often referred to as speed brakes. Wheel brakes are applied, and reverse engine thrust is also activated. Reverse thrust is where the air exiting the engine is redirected forward to in effect blow the aircraft backwards and help slow it to taxi speed.
Taxi-in to the terminal
This is manoeuvring from the runway after landing to the terminal via the taxiways to a designated arrival bay.
AirAsia X is also implementing a number of initiatives to ensure the most of the flight phases are conducted in the most efficient manner:
- Packs (Air-conditioning) off take-off
- Reduced thrust take-off
- Optimization of flight level and cruise speed using advanced flight planning system
- Reduced flaps take-off/landing
- Idle reverse landing
- One engine taxi in