Narrative:

Even though the [takeoff data] was briefed beforehand somehow flaps were set to 1 on the taxi even though planned for 2. Immediately upon ATC contact we were given a runway change and elected to do the taxi checklist later at the end of the runway. We changed the flight plan and I reloaded the box and still hadn't caught that the flaps were in configuration 1 instead of 2 even though the box was set for 2. The taxi checklist was called for below the line and both of us had not realized we never did before the line. This was a huge error as we were hurrying to comply with ATC in getting out in front of a certain aircraft. All configuration tests showed normal. We took off completely normal and the only time we realized the flaps were set to 1 instead of 2 was when the captain called flaps 1. This event occurred due to multiple distractions at very important phases of the taxi. The way the threat and error model is set up; this should have not occurred; but still did. We were both at a loss at how this could have happened to us when there are multiple checks in place to prevent it from happening.this amount of time myself and the captain have spent reviewing what happened and replaying the event is a start. There are adequate steps to avoid this and somehow we were distracted at just the right times at every one. There is really nothing more that needs to be done procedure wise; just more attention to detail on our part.

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Original NASA ASRS Text

Title: A321 flight crew reported multiple distractions resulted in taking off with the incorrect flap setting.

Narrative: Even though the [takeoff data] was briefed beforehand somehow flaps were set to 1 on the taxi even though planned for 2. Immediately upon ATC contact we were given a runway change and elected to do the taxi checklist later at the end of the runway. We changed the flight plan and I reloaded the box and still hadn't caught that the flaps were in configuration 1 instead of 2 even though the box was set for 2. The taxi checklist was called for below the line and both of us had not realized we never did before the line. This was a huge error as we were hurrying to comply with ATC in getting out in front of a certain aircraft. All configuration tests showed normal. We took off completely normal and the only time we realized the flaps were set to 1 instead of 2 was when the Captain called flaps 1. This event occurred due to multiple distractions at very important phases of the taxi. The way the threat and error model is set up; this should have not occurred; but still did. We were both at a loss at how this could have happened to us when there are multiple checks in place to prevent it from happening.This amount of time myself and the Captain have spent reviewing what happened and replaying the event is a start. There are adequate steps to avoid this and somehow we were distracted at just the right times at every one. There is really nothing more that needs to be done procedure wise; just more attention to detail on our part.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.