Hot answers tagged

95

The plane is probably taking off. The flaps are hard to see but they don't quite look to be extended enough for landing (Looks like flaps 20). On a 747 they extend to around 45 degrees (flaps 30, but they curve around more than that) for landing and have a huge, unmistakable profile. Further, we know it's KBFI and we know the plane is on 31L from the ...


57

You should wait until clearing the runway before performing any non-essential checklist items because you are still in a critical phase of flight and at a relatively high risk while still on the runway. You should focus 100% of your attention to controlling the airplane (don't stop flying the airplane until you come to a complete stop) and watching for ...


42

Please skip to the edit after the picture to see my actual answer. I'm leaving my original answer intact though, since other answers have referenced it. I'm guessing that's it's taking off because: The wheels appear to be spinning (though the picture is kinda grainy so...) There isn't any smoke behind the tires, even though it would have just touched down....


41

Fully permitted according to this Configuration Deviation List for the A320: One fairing may be partly or completely missing. There are more posts about this occurring. As Noah Krasser points out, it looks fairly dodgy to observant passengers. This is the "Master" list, i.e. the safe and approved baseline. Some airlines may have changes in their own ...


36

Why no flaps? Flaps change the pitching moment of a wing. After all, they add lift over the full chord, so the sum of the increased lift attacks at about mid-chord, which is a quarter chord aft of the regular lift. If there is no separate tail surface to compensate for the pitching moment caused by that extra lift, the aircraft will quickly pitch nose-down ...


35

Raise the flaps after leaving the runway. Consider: A light single doesn't weigh that much and in the short time slowing down from the speed you touchdown at and taxi speed, the difference in weight on wheels between flaps 0 and flaps X is not worth worrying about unless you are landing on a true short field. If the crosswind is that strong, you still need ...


31

Flaps are at the back of the wing, slats are at the front. Easy! :) If you want it more technical: They both help to generate more lift. See these diagrams with angle of attack and lift coefficient: As the lift coefficient is inversely proportional to the minimum airspeed, a higher CL will allow a lower Vmin.


31

For the same reason that you don't takeoff with full flaps. Because the climb performance sucks. Flaps do add lift, but also a lot of drag. A low flap setting often provides more lift than drag, assisting climbout, whereas full flap offers a whole lot of drag, which is desirable when you want to be slow for landing. But a go-around necessitates gaining ...


30

Stays where it is. The mechanism is a leadscrew and like most leadscrews it's "self-locking", which means that it's held in position by frictional forces whenever the motor isn't turning and it can't be back-driven even by substantial loads. The 20 degree (etc) "stops" are just reference positions for which aircraft performance and load limit data have been ...


29

From the A320 Flight Crew Operating Manual (FCOM): And the image to text: On ground, hot weather conditions may cause overheating to be detected around the bleed ducts in the wings, resulting in “AIR L (R) WING LEAK” warnings. Such warnings may be avoided during transit by keeping the slats in Configuration 1 when the OAT is above 30 °C. (Emphasis mine) ...


27

The short answer is, it depends. The FAA Airplane Flying Handbook merely states that this can be performed once the aircraft has established positive climb, but does not specify exactly when. Ultimately two situations arise: The airplane is sufficiently large/high performance that normal operating procedures specify the use of flaps for all takeoff ...


25

This picture is most likely taken during landing. The flaps configuration is the best clue. Flaps are extended more for landing than they are for takeoff. Compare with other pictures of Air Force One: OP, brightness adjusted: Landing (original) Takeoff (source) The difference in flaps is a bit subtle but seems to match landing best. Other good clues for ...


22

Raising the flaps right after touchdown. Good or Bad? -- The answer is an emphatic Yes. The major reason for not raising your flaps until you've cleared the runway and come to a stop is that it's one more thing for the pilot to do in an already workload-intensive period (landing). As others have pointed out you might hit the wrong control or otherwise mess ...


22

Yes take-off without flaps is possible. The Airbus A300 and Boeing 767 are approved for such take-offs and it is being done regularly. It results in a better climb gradient, especially with one engine out. The one engine out climb gradient is an important and sometimes limiting factor in take-off calculations. One important constraint is the length of the ...


22

Yes you must slow down to the white arc, or whatever your flap extension speed is for a given condition, regardless. If you are 10kts above the white arc and drop flaps anyway, it's not going to make the airplane come apart, and if you did it once, slap yourself on the wrist and don't do it again. It's putting stress on the flap attachments beyond what ...


21

First, you have to remember on some configurations, the lower stages of flap will mostly add drag and very little lift. Sometimes that extra notch of full flaps is only there to change the camber of the wing to add a bit of a nose down attitude to help with visibility on landing. Both are items you do not require on takeoff. Now, when selecting flaps for ...


21

Nobody can definitively answer this for you except Cessna's 1965/1966 engineering team (the year they made the change), but there are two reasons I can think of: Because switches are cooler than Johnson bars; or Because everyone else is doing electric flaps. Much like with manual transmissions, some people just don't like the extra work of manual flaps, and ...


21

The slats help to protect the outer wing from stalling when the flaps deploy. The outer wing carries the ailerons, so there are no flaps, but the flaps inboard will induce more lift on the whole wing, raising the effective angle of attack even in the aileron section. Slats push the stall angle of attack up. Without the protection provided by the slats, the ...


21

Flaps change the camber of the wing's airfoil. This in turn changes the zero-lift angle of attack, increases the maximum lift potential and, in case of fowler-type flaps, the wing's area. Airliners use flaps on both take-off and landing, and most of the time they are only partly deflected. Full deflection is only set on final approach to reduce the landing ...


20

Measured directly on the image, the angle between the cheatline and the runway is 5.5°; the true pitch angle of the plane will be slightly less than that, because of a little perspective foreshortening. According to this document from Boeing, a typical liftoff attitude for a 747-400 is 10°. (The VC-25 in the picture is a modified 747-200, but none of the ...


20

You don't say which variant you're flying, but the C42B is perfectly capable of both taking off and landing with zero flaps on a reasonable-length runway. I've done it on several occasions with huge margin even for touch-and-gos on my home field's 1300 m asphalt runway. You do need to adjust the angle of attack (via pitch), but if you're flying the airspeed ...


19

Flaps increase lift and drag by changing the camber of the airfoil, and allow lower airspeeds. There is also an effect of shifting the center of pressure (C of P) aft. There may be an immediate decrease in airspeed due to the increase in drag (see the Wikipedia article linked below) until the aircraft regains stability by nosing down. There are some ...


19

Even the largest commercial airliners are able to land without flaps, since flap failures do happen occasionally. See a report here where an A380 landed with no flaps. This was at the Auckland, New Zealand airport, where the runway is 3,635 m (11,926 ft) long. The pilots have checklists to follow in the event of issues with flaps, which include information ...


19

For the Boeing 727-100 and 747-100/200 the answers are: when does the system know when to sound the alarm? When the thrust levers are advanced to begin the takeoff, if flaps and slats and a few other things are not in takeoff position, a loud horn sounds. figure out at what speed they can take off without flaps and slats. Takeoff is not permitted ...


18

A few different reasons: Good pilots put the aircraft into a well-known (up) configuration after landing, so that the aircraft is ready for use on the next flight. Flaps down during taxi was a signal to the tower that the aircraft had been hijacked. Take-off flaps (10 degrees on my airplane) and landing flaps (45 degrees), are nearly always different, so ...


18

It could have been as you witnessed. In 2005, a modification package dubbed Quiet Wing was offered for the 737-200 and the 737 Classic (-3/4/500) that would droop the flaps by 4° for all phases of flight. [It] decreases drag for cruise, and increases the aerodynamic efficiency of the wing by between 2% and 3%. The NTSB in 1981 also found that many 727 ...


18

Because there is a maximum deployment speed for things like flaps, gear extension (and sometimes retraction). Exceeding these speeds and using those devices can cause damage to control surfaces or other equipment. The speed check is there so that when the PF calls for flaps, the PM remembers to check the speed before performing the action.


17

Specific information can be difficult to come by, and each airline may have their own guidance on the subject. I wasn't able to find anything for the 787, but for the according to one 777 crew handbook I found, flaps up landing was not part of certification: All Flaps and Slats Up Landing The probability of both leading and trailing edge devices failing ...


17

Below is sample screen of a Boeing 777's Primary Flight Display. See those flaps marks on the speed tape? Here's the thing: you don't want to retract the flaps from 5 to 1 when you're slower than the stall speed at flaps 1. So in terms of flaps retraction schedule, you'll: Accelerate to (at least) the minimum speed for flaps 5 in the takeoff roll. Pitch up ...


17

Spoilers are used to shed energy when the aircraft is too fast or too high. That means they need to be used when the aircraft is flying fast and are designed accordingly. On the other hand flaps are used to increase lift and when flying fast, there is plenty of lift, so there is no point in using flaps at high speed and therefore they are not designed for ...


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