There appears to be some misinformation continuing to go around our Airbus pilot group concerning the belief that flaps 2 is better for takeoff and second segment climb performance, when just the opposite is true. All we need to do is use our Flysmart + Takeoff performance optimizer for flap setting to give us the best performance information.
Flap setting has an affect on the wing’s lift coefficient and on the aerodynamic drag. Increasing flap angle increases the lift coefficient, and therefore reduces stalling speed and the required takeoff speed (the same lift will be created at smaller air speed due to greater lift coefficient). This reduces the takeoff distance. In the same time increased flap angle beyond optimum increases drag, reduces acceleration, and increases the takeoff distance.
The net effect is that takeoff distance will decrease with increase of flap angle initially, but above a certain flap angle the takeoff distance will increase again. An optimum takeoff setting can be determined for each type of aircraft and any deviation from this setting will give an increase in the takeoff distance.
The flap setting also affects the climb gradient. Increasing the flap angle increases the drag, and so reduces the climb gradient for a given aircraft mass. If there are obstacles to be considered in the takeoff flight path, the flap setting that gives the shortest takeoff distance may not give the required climb gradient for obstacle clearance.
It is important that we not rely on past standards of companies they have worked for and use standards set forth in our manuals . We unfortunately have a number of items like these and others that are still being propagated by many and are in desperate need of being cleaned up. I truly believe that the best cockpit environments are ones that safe, efficient and with a free flow of ideas and communication. I have found that the best way to accomplish this is to have the correct information be promoted by our training and management Captains.