I don’t fly much. In fact, the trip I took this past weekend accounted for my first flying experience in over 2 years.
That said, I noticed something I considered quite odd on all 4 of the flights to and from my destination.
On approach toward landing, there is an obvious slowing of the aircraft. That is to say, I noticed myself being pushed forward in my seat as the aircraft slowed, as opposed to the pushing back in the seat one experiences on takeoff. However, on each landing, shortly before (15-20 seconds) the plane touched down, I noticed that the feeling of being pushed forward suddenly stopped. I didn’t necessarily find myself being pushed back in the seat again as if the pilot had suddenly ‘hit the gas’, but it was obvious that he did lay off the brakes, giving the sensation that the plane was picking up speed just before landing.
IANAPilot, but I play one on my computer. My understanding is this: the approach to the runway is essentially a powered glide. The idea is to lose both altitude and airspeed. This undoubtedly contributes to your feeling of deceleration, probably combined with the nose-down orientation of the aircraft. Before touchdown, the pilot will ‘flare’ the aircraft: pull back on the stick such that the nose pitches up. The entire plane (with you inside it) is tilted nose-upwards. You are now essentially leaning back in your seat, so you no longer have the feeling of being pushed forwards. In other words, it’s all due to gravity.
It’s definitely nose-up during the landing itself. I’m not so sure about the descent or approach. I’ve flown on a lot of passenger jets and I don’t recall seeing the ground tilted either way. It’s probably a very subtle thing. Hopefully a pilot will be along shortly.
IANApilot either, but I believe large commercial planes approach with a nose-up attitude. From what I understand, once these planes get below a certain speed, you control them in a counter-intuitive fashion. That is, you adjust your altitude by working the throttle (more gas=go higher) and you adjust your speed by working the stick (point nose down=go faster).
The only time I recall a nose-down approach was in a general aviation aircraft with a new pilot at the controls.
On approach, airspeed is controlled by attitude and rate of descent by power. At least that’s how it works with little planes - I’m assuming big ones fly the same way. So, to slow the aircraft’s forward speed, the nose is pulled up. The amount of power applied translates to the amount of lift the wings are generating.
I’m guessing the sense of picking up speed just before landing is related to the nose coming down and the visual clues of the ground whizzing by (I’m assuming you could see outside the plane) Once all the wheels are down, the brakes and exhaust deflectors slow the plane rapidly so it can get off the runway.
As an airplane begins its approach for a landing, the pilot will engage flaps – these, uh, flaps are located on the trailing (back) edge of the wing, and both slow down the aircraft and generate more lift, allowing the aircraft to fly at slower speeds. On big airliners, you can look out the window and see the flaps deploy outwards and down, and often you’ll see the leading (front) edge make cooresponding movements out and down.
Depending on the aircraft, engaging the flaps will often cause the plane to nose down a bit, adding to that feeling that you’re moving forward in your seat.
As the plane nears the runway, it will be more or less gliding to a landing, with full flaps, gear down, and minimal engine power. The pilot may adjust the height of his approach by adding or taking away engine power. Giving a little shot of power on final approach to correct the approach may cause you to settle back in your seat for a moment.
Like Terminus says, just before touchdown, the pilot will flare the aircraft, which allows the plane to touch down with it’s main wheels first. It also gets rid of excess airspeed, so that the plane touches down at the slowest speed that it can fly (aka stalling speed).
Some airliners also have thrust reversers, which are panels that deploy around the engine to divert the thrust of the engines to help the plane slow down. Thrust reversers and brakes help stop the plane once its wheels are on the runway.
That is almost certainly your answer. When a pilot goes to full flaps, you will almost certainly feel it as a rather sudden decelleration. This goes away rather suddenly and you will sometimes get pushed back into the seat just as quickly as the pilot is contolling the plane largely just by the throttles at this point.
At LAX, the signs on the streets approaching the airport have drawings of a departing aircraft and an arriving aircraft.
The arriving aircraft is drawn landing with its nose down and its tail up. My brother turned to me the first time he saw that and said, “I don’t want to come back on that plane.”
IANAP either, but ny understanding is that flaps are NOT particularly used to slow the plane down. In fact, the slowing is an almost unwanted by-product of their use. The flaps can be thought of as more analogous to a gearbox than to brakes. Large jetliners don’t like flying at the low speeds required for take-off and landing, so the flaps are used to make the wing more “winglike” simply to keep them from falling out of the sky at these speeds. This actually requires the pilot to increase thrust a short distance away from the runway, to counter the higher drag of the full flaps position. A railway station I use is just at that distance from the airport (coupla miles maybe) that the planes seem to glide in quietly, and then immediately overhead you’ll hear it powering up slightly (to LAND!).
That is only partially true and not really true at all in this case. Flaps are mainly used during two phases of flight: takeoff and landing. For taking off, your point is true. The flaps are used to gain lift and decrease the speed that the plane needs to take off. Drag is unwanted at this point because the plane needs to accelerate. The flag setting used during takeoff is only partial extension of the flaps. This a good compromise between increased lift and only a moderate increase in drag.
During landing, the flaps are deployed further than during takeoff. This is because increased drag is a wanted effect in this case. Airplanes are designed to be very aerodynamic and they don’t slow down well at all especially when they are descending for landing. The increased drag from the flaps make it possible to descend and lose speed while on landing approach. The speed at which an airplane lands is critical. Too slow and the airplane may stall and too fast, it will simply float just above the runway or cause the pilot to bounce if the pilot tries to force it down. The increased drag from the flaps means that the pilot can control speed more precisely. The flaps try to slow the airplane and just enough engine power can be used maintain the proper approach and landing speed. In this configuration, the pilot can simply chop the power just above the runway and decelerate while in the flare and touch down smoothly. Without flaps, the plane will tend to just float all the way down the runway and never settle to earth.
Flaps are not the only devices used to increased drag. Most airliner wings have spoilers also. They are surfaces that pop up from the top of the wing at an angle and greatly increase drag without adding lift.
Point taken Shag. You’re quite right, though aren’t spoilers primarily used to “spoil” the lift (hence their name), and added drag is only a bonus? Isn’t the idea just to keep the plane glues to the tarmac? This is why they seem to be used after touchdown?
Anyhow, pilots of large jets do seem to increase thrust some distance from the runway (as opposed to “flaring” over it). The lift / drag compromise on landing still has me curious, and I suspect it’s quite complex.
True story: My dad was in the FAA at the FSS at DAG. Mojave Desert. The temperature was about 110°F and the sun was beating down on the black asphalt runway. A Cessna 150 came in on a normal approach. The hot air over the runway caused the Cessna to balloon as soon as it got over the asphalt. The pilot tried a couple of times to get down, but would just float over the runway. He finally figured it out, of course, and came up with a power setting that would allow him to land. (My habit, at WJF, was to always make full-stall, power-off landings so I could definitely make the turnoff without using the brakes – unless I didn’t fly the pattern correctly and had to add power, in which case I would have been in trouble if the engine quit. Winds permitting, I’d always use 40° flaps.)
As I said, I liked full flaps on landing. But power-on landings often resulted in “greasers”, while on even very nice full-stall landings you were definitely staying down. One reason to carry power until you’re “over the numbers” is that you will be in a better position in case of an engine failure. Jet engines, unlike piston engines, do have to “spool up”, so there is a lag between the time you apply power and the time you actually have the power.
Regarding flaps, I mentioned somewhere else that my instructor once took off with the big Cessna barn doors all the way down. (Later models restricted the flaps to 30°, though we had 40°.) So you can take off – at least in some airplanes – in such a configuration. Normal takeoffs in a 172 are made with the flaps at 0° to 10°. 10° flaps will reduce your ground roll by about 10%. According to the POH, taking off with more than 10° flaps is not approved.
There’s a rule regarding flaps: “Flaps down, nose down.” When you lower the flaps the nose tends to rise, so you trim down. On landing, especially if you’re in a Cessna with 40° flaps, the nose needs to be down quite a bit to maintain your airspeed. (Pitch is primary speed control, while throttle is used to control your altitude.) With full flaps, you’re descending more quickly and the deck angle can be a little steep. So if you’re flying at say, 80 knots, and you apply full flaps so you can make a nice steep descent at 70 knots, you’re “putting on the brakes” and your body tends to feel the forces. Plus, you’re pointed down a bit which makes you feel as if you’re straining a little against the seat belt. On landing if you apply power then you are creating an accelleration force in the opposite direction. You’re also flairing. Since you’re bringing the nose up you need more power or else you’re going to lose too much airspeed. (I know I said speed is controlled by pitch, but you can see that flying is all about power management and that pitch and throttle are used together to maintain the balance. Power-off approaches and landings mean that you have to balance the forces without adding power to the engine and if you do it right then you run out of flying airspeed and altitude at the same time.) So your deck angle decreases or changes to the opposite direction and you are adding power to maintain your speed. The felt forces thus change from “putting on the brakes” to more or less neutral.
Of course I haven’t flown a fixed-wing in years, so I’m not sure if I’m explaining it correctly. Helicopters don’t have flaps! (Although some do hae “flapping hinges”, but that’s an entirely different thing and is another story.)
I am a pilot, but I do not fly transport category aircraft. However, every single one of my takeoffs has resulted in a landing, so I feel qualified to speak a little bit on the subject. I am speaking of my small aircraft experience here:
The main thing to keep in mind is that your senses are very unreliable when it comes to flight. What you are feeling is no indication of what the aircraft is doing. Training to overcome these sensations is a major part of a pilot earning his/her instrument rating.
I fly approaches either way. When I am flying a visual approach, I pitch to maintain an airspeed, and use power to adjust my descent rate. On an instrument approach, however, I find pitch is much quicker to respond when trying to maintain the glideslope. If the glideslope needle starts to barely indicate that I am low, I give the yoke a slight tug back to arrest the movement. The airspeed will drop a bit, which I correct with a little added power.
Bingo
**It depends. In my small plane, an instrument approach can place me right over the end of the runway, but 500 feet high. Shortly thereafter, my plane assumes a definite nose-down attitude
Flaps add lift and drag. About 10 degrees for takeoff gets you more lift with a small drag penalty, but the more you add gradually gets you more drag than lift. 10 degrees is fine for takeoff, but usually any more than that is used only for landing. In the 172, putting down 40 degrees of flaps all at once feels like someone threw out an anchor. The nose pitches way up, and the airspeed rapidly drops off. Put the nose down to get your airspeed back, and the thing will come down like a brick tied to an anvil.
Generally, the aircraft will have a nose-down attitude for the approach. In the 172 (the last fixed-wing I flew, and the one in which I have the most experience) the approach speed is 70. On take-off, I rotated at 60. So you need to raise the nose to bleed off excess speed (landing speed flaps up, power off is 51 knots and flaps down, power off is 46 knots). You also don’t want to land on the nose wheel, which is relatively fragile. You set down on the mains. You need to have the nose up to do that. So what you do is maintain nose-down until a bit before you reach the runway, then flair the aircraft to give it a nose-up attitude and to bleed airspeed.
I have a question (from a dedicated flight simmer) a bit off topic, but about landing: don’t most modern commercial aircraft (Boeing, Airbus) have the capability to land the plane completely automatically, all the way from engaging the ILS to the stop on the runway? Technically, couldn’t the pilot take a nap while landing?
I’ve never flown a jet aircraft. However, I had a lot of experience in rather large and fast, for the time, aircraft. The nose-up or down attitude on landing depends a lot on the trim of the particular type of aircraft. For example, the Martin B-26 aircraft through model C had the wing incidence angle (relative to the fuselage centerline) at a certain angle and tended to fly nose-up at approach speed. Subsequent models G and F (D and E were never operational) had the wing incidence increased by about 3[sup]o[/sup] and flew with a more nose-level fuselage angle which made for a lot better visibility on flare out for landing.
I also understand that with jets, the jet engine responds rather slowly to commanded power increases so the RPM are kept high on approach so that a missed approach can be made if needed. The aircraft is then flown at a constant airspeed and the descent rate is controlled by flap setting and spoiler devices. I think most really large aircraft, these days, make landings using the ILS glide slope and localizers and many landings, if not not most, are done by automatic computer control.
On aircraft carrier landings, incidently, the technique is to apply full take-off power at touch down so that if the arresting wire is missed a go around is possible. If the wire is caught the throttle is then cut back.
As to physiological effects on passengers, I would think these are so individual, including what you had to eat and your particular degree of apprehension, as to render information on what the causes are is mostly guesswork.
Yes, many do although it requires a plane with that capability and an airport with an ILS equipped for it. The pilots can’t just sleep because they have to program the autopilot for the landing (plus, it is bad form and against the rules). Still, pilots do use autoland sometimes especially in really bad weather. It is technically possible for the pilot to do no hand flying from the point that the plane is lined up on the runway center-line for takeoff all the way to the plane being stopped on the runway. However, airline pilots tend to like flying and if they used the system often, they would tend to get bored and their skills would deteriorate. Autopliots already do much of the en route flying.
David Simmons: Speaking of wing incidence, have you looked at the F-8 Crusader? It had a variable-incidence wing so that the nose could be lowered when landing. I used to have a wing-incidence control, but I traded it for some other aviation stuff years ago.
I am speaking of my small aircraft experience here: