What you see, hear, and feel on a typical airline flight – Continued
Part II – Going Down
Pilot Activity: At this point, the aircraft is probably flying on autopilot. The autopilot can maintain altitude, speed, and navigational control of the aircraft. The pilots, however, are expected to monitor the aircraft’s performance, look outside, etc. They also have to respond to ATC. As they travel, the aircraft will pass through different ATC sectors. Each time they reach the boundaries of a sector, ATC instructs them to switch radio frequencies and contact the next sector–the pilots are in constant contact with ATC along the entire route.
Cabin Crew: The Flight Attendants tend to their assignments such as food and beverage service. At this point, passenger courtesy toward flight attendants can go a long way toward a more enjoyable flight. Note that Flight Attendants or the Cabin Crew are responsible for safety and compliance first, drink service is a courtesy provided by the airlines. For example, when the pilot turns on the seatbelt signs, the flight attendants are responsible for ensuring that all passengers are in their seats with their seatbelts fastened. Passengers are expected (actually required) to follow the directions of flight attendants.
The Aircraft: This is the best part of the flight for the aircraft. The air is cool, which makes the engines more efficient. This means fuel consumption is low. The engines are set at a comfortable cruise power setting. The only sound is the steady hum of the engines and airflow around the airplane. Occasionally, you may see an aileron move up or down—slightly—as the aircraft makes a slight directional correction.
Phase: Enroute Descent
Pilot Activity: Perhaps a hundred or more miles from the destination airport, ATC will clear the pilots to begin a descent. The pilots reduce engine power and ease the nose down to descend. The airspeed may not change because of the descent. At this point, the pilots are reviewing the arrival procedures for the airport, and making sure that the radios and navigation instruments are properly set. There is also an increase in communications between the pilots and ATC. One pilot is responsible for actually flying the airplane while the other handles the radio communications.
Cabin Crew: At this point, the Flight Attendants are also preparing for arrival. They collect all of the food and beverage items remaining in the cabin and go through their own procedures preparing to secure the cabin for arrival and landing. There may also be several cabin announcements during this period.
The Aircraft: The aircraft is in a powered glide. The engines are set at a lower power, but it is descending at cruise speed. The aircraft may pass through different layers of air and encounter mild to stronger turbulence—or it may be smooth throughout the flight. Other than hearing the engine power being reduced and feeling the nose of the aircraft angle slightly downward, there will be little perceptible sensation in the cabin. Occasionally one or more spoilers will extend upwards, either to slow the aircraft or if only on one side, to aid in turning the aircraft.
Pilot Activity: If the pilot needs to descend a little more quickly, he does not point the nose down farther. Rather he may reduce the power and deploy one or more spoilers on the wings. These are like flaps that open upward on the back of the wing in front of the flaps, like a small fence. When they come up, they disrupt the flow of air over the wing in that area and reduce the lift produced by the wing. Less lift means the aircraft descends more quickly without needing to go into a steeper dive. The pilots can control the rate of descent by increasing or decreasing the degree of deflection of the spoilers.
As in the climb, during the descent pilots may have to level the aircraft on instructions from ATC. In that case, the nose will come up to level and the engine power will be increase to maintain cruising speed in level flight. When they are cleared to continue the descent, the engine power is reduced and the nose eases down.
Phase: Approach to Landing
Pilot Activity: At this point, the pilots are actively engaged in preparing for the approach to landing, including following ATC instructions that will align the aircraft with the runway, and reviewing the published approach procedures for the airport and the active/assigned runway.
Cabin Crew: The Flight Attendants finish the last-minute clean-up in the cabin, check that seatbelts, tray tables, and seatbacks are secure and in the proper position. These are all safety items. A signal from the cockpit instructs the cabin crew to return to their seats, buckle up, and prepare for landing.
The Aircraft: The aircraft is now flying at 5,000 to 2,000 feet above the ground. Passengers can see buildings, cars, trees, even people on the ground. During this phase, the aircraft will likely be making turns as the pilot maneuvers around the airport to line up with the assigned runway.
This is the best time to see the ailerons in action. If an aileron deflects downward, that wing will rise, and the aircraft will begin a turn away from that aileron (i.e., when the left aileron goes down, the aircraft banks and turns to the right, etc.) On some aircraft, spoilers are used to aid in turns. If a spoiler is raised on the left wing, that reduces the lift on that wing and the aircraft banks to the left. Prior to lining up with the runway, the pilot may use the flaps to allow the aircraft to fly more slowly—there are speed limits as aircraft approach the airport.
Once the aircraft is approaching alignment with the runway, things begin to happen more quickly.
Some degree of flaps will be lowered to allow the aircraft to slow. Flaps do two things. When deflect partially, they increase lift that allows the aircraft to fly slower. There may be an increase in power to overcome the drag of the extended flaps. The pilot is now ready to head down the final approach path.
Phase: Final Approach to Landing
Pilot Activity: The pilots are fully focused on the landing. One pilot is flying the aircraft, controlling both the flight controls and the throttles. The other pilot is scanning instruments, watching the airspeed, perhaps calling out the airspeed during the landing. Both pilots scan the airspace and airfield in front of them. They have to be prepared in the rare event that a car, or airplane, or deer goes out on the runway in front of them and they cannot land safely. The other pilot responds to commands for more flap down deflection as the aircraft approaches the runway.
This where it is really fascinating to watch what is going on with the aircraft. As the aircraft approaches the point where it will begin the descent to the runway, the pilot extends the landing gear. The sound of more mechanical action, maybe a whine of hydraulic pumps, and then the comforting thump as the landing gear locks into place with the gear down. As the aircraft reaches the point where it must descend along the glide path to the runway several things happen. The flaps are extended farther, and the power is slightly reduced. With the flaps extended, it takes power to maintain speed.
The power is only slightly reduced. The aircraft will be slowed not by reducing power, but by further extending the flaps. It requires a good bit of power to keep the plane flying and not descending too quickly. But it also allows the aircraft to approach the landing at a lower speed.
Airspeed is critical. Too fast and the aircraft will land too far down the runway and may not be able to stop. Too slow and it may settle onto the ground before it gets to the runway. Fortunately, with training and practice, maintaining the proper speed and glide path is repeatable task.
As the aircraft crosses over the end of the runway, the pilot gradually reduces the power and raises the nose of the aircraft, holding it off the runway, letting the aircraft slow and gradually settle onto the runway in the landing zone.
The Aircraft: As soon as the aircraft touches down, there is a bit more activity. The throttles are moved to idle, the spoilers are fully extended; flaps are full down producing drag. The pilot then moves the throttles to reverse thrust. Reverse thrust redirects the engine exhaust in a forward direction, using the engines to help slow the aircraft. Passengers will feel a distinct sensation of slowing.
As the aircraft slows, the pilots begin to brake with the tires. Once the aircraft has slowed sufficiently, the engines are brought out of reverse thrust, the spoilers retract, the pilot continues to use tire braking and slows to a speed that allows him to turn the aircraft off the runway.
Cabin Crew: The Flight Attendants remain seated with the passengers until the aircraft is clear of the runway and the pilots signal that it is safe for the flight attendants to move about.
Phase: Taxiing to the Terminal
Pilot Activity: Once off the runway, the pilots contact Ground Control for clearance to taxi to the terminal. This can be a short trip or a long route to get to the assigned gate at the terminal. The pilots are alert for any traffic on the ground, and are also busy shutting down certain systems that are no longer needed.
Cabin Crew: Once on the taxiway back to the terminal, the cabin crew gets a signal from the pilots that it is safe for them to move about. They provide an arrival briefing and more safety instructions.
The Aircraft: The aircraft moves along smoothly toward the terminal. Along the route, the pilots may shut off one of the engines. This is to save fuel. The aircraft can taxi equally well on one engine. Some aircraft have an auxiliary power unit—a small jet turbine in the back of the fuselage runs electrical and air conditioning on the ground.
Phase: Docking and Deplaning
Pilot Activity: The pilots taxi the aircraft into the gate area, guided by a flagman and two wing walkers. Once in position, the pilot sets the brakes and shuts down the engines. The aircraft is attached to an external power unit to keep power on for cabin lighting and air conditioning on the ground. The pilots shut off the auxiliary power unit. Then the pilot turns off seat-belt sign and…
the passengers all jump up at once to open the overhead compartments!
Cabin Crew: The Flight Attendants assist and guide in the deplaning process.