Question: On the sidesticks of Airbus aircraft, there is a Priority Takeover button. [Wikipedia](http://en.wikipedia.org/wiki/Side-stick) has this to say:

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> In typical Airbus side-stick implementations, the sticks are independent. The plane's computer either aggregates multiple inputs or a pilot can press a "priority button" to lock out inputs from the other side-stick.
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On US flight 1549, [the CVR transcript](https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1003.pdf) shows that Sully hit the Priority T/O button, after the co-pilot (Skiles) handed over control of the aircraft:

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> *15:27:23.2* - **Sully:** My aircraft.
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> *15:27:24.0* - **Skiles:** Your aircraft.
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> *15:27:26.5* - **FWC:** Priority left.
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I'm curious as to why there's a need for this button at all?

Here's a short video on YouTube, demonstrating this:

Answer: 
It's been several years since I worked at United's flight training center, but if my memory serves me, it is there in case the system is receiving input that the pilot wants to exclude. As was explained to me, an example of this would be the other pilot becoming incapacitated, with their body leaning against the sidestick. In this case, one would want to use the Priority Takeover button to eliminate the other pilot's input.

In Captain Sullenberger's case, it is likely that he wanted to ensure that First Officer Skiles wasn't providing any control inputs that would work against his control inputs. 

Now, it is also my understanding that such functionality is not useful in a "hostile takeover" event, since the other pilot can also attempt a priority takeover (or use physical force, due to the close proximity of the two pilots).
As far as I recall the priority button suppresses the other stick **and autopilot**. Since it is right under the thumb on the side-stick, that makes it quicker way to disconnect autopilot than navigating the other hand to the flight management panel.

The overall idea is that when the pilot needs to make manual input quickly they simply push that button and it will ensure that input will be obeyed, so they don't need to think what state the system was in.

Note, that the priority take-over button will disconnect autopilot immediately when pressed, but it only disables the other side-stick while held down, or permanently when held down for more than 40 seconds. The last case is primarily for situations when the other pilot is incapacitated holding their side-stick deflected or when the other side-stick fails.