# What is the difference between flaps and slats?

I have heard pilots talk about flaps and slats, seemingly interchangeably.

Is there a difference between a flap and a slat or they are the same thing?

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.

• Both the lectures that I know and almost all sources on the internet describe a reduced stall AoA with flaps, i.e. a c_L / alpha curve that is moved both up and towards the left. This is important, because it means that an extension of the flaps alone can cause a stall without changing the AoA. Forum post with good sources: forums.x-plane.org/?showtopic=59032 Commented Mar 18, 2015 at 9:50
• Just wanting to point that flaps can be located both at front and back of the wing (trailing-edge or leading-edge flaps), while slats only exists at the front. Main difference between slats/flaps is not location ,but (as you pointed out) functionality Commented Jul 28, 2015 at 13:57
• How the drag coefficient affected by the slats and flaps? Commented Nov 13, 2018 at 9:16

Slats and flaps both change the shape of the wing when they are extended and allow the wing to generate more lift so that the airplane can fly slower.

Operationally they are both retracted and flush against the wing except for takeoff and landing at which time they are extended.

Pilots tend to refer to them together because they are used for the same purpose and used at the same time. In fact, they are normally even moved by using the same control (typically the slats comes out when selecting first detent, and then the flaps come out progressively further at each detent):

Slats are on the front of the wing (on the left in this picture) and the flaps on on the back of the wing (on the right). As you can see, they both tend to make the wing bigger and more curved when they are extended:

• It's worth noting that there are also autoslats, which extend automatically at high angle-of-attack, so it's not quite true that slats are only used at take-off and landing. Commented Aug 25, 2015 at 18:16
• @DanHulme "Operationally" that is the only time that they are used. My airplane also has auto slats, but they only extend during non-standard events (flying too slowly without them extended), and I don't feel that the autoslat feature adds any to the discussion of what they are for. :) Commented Aug 25, 2015 at 18:21
• That's fair enough. I just think alpha protection is a good enough use to merit a mention, even if only as an aside, as it's something you can't reasonably do with flaps. Commented Aug 25, 2015 at 18:27