CRJ700 flight crew and flight attendant reported changes to their takeoff clearance distracted the f...

Narrative:

We departed from ord; and skipped the before takeoff checklist above the line. We taxied out behind a [heavy] B757 and realized that we would have to get normal takeoff performance. We sent for the numbers; but unfortunately we received an ACARS nocomm message instead. The first officer used the release and the performance cards to reset the speeds and the flaps from 8 to 20 degrees. The tower then resequenced us behind an MD80; so we reset the speeds and the flaps back to the original numbers. When our turn came the tower instructed us to line up and wait and said that it would be 2 minutes for wake turbulence for a heavy landing on the crossing runway. As I started to move forward; the tower then issued an immediate takeoff clearance with crossing traffic on a two mile final and I rushed.as has been said many times; don't let ATC rush you! I allowed external distractions to overwhelm me for a few minutes. I should have stuck with normal thrust and not tried to reset back to flex thrust. And I should not have accepted the immediate takeoff clearance.

Original NASA ASRS Text

Title: CRJ700 flight crew and Flight Attendant reported changes to their takeoff clearance distracted the flight crew and caused them to takeoff before completing checklists and alerting the Flight Attendants.

Narrative: We departed from ORD; and skipped the Before Takeoff Checklist above the line. We taxied out behind a [heavy] B757 and realized that we would have to get normal takeoff performance. We sent for the numbers; but unfortunately we received an ACARS NOCOMM message instead. The FO used the release and the performance cards to reset the speeds and the flaps from 8 to 20 degrees. The tower then resequenced us behind an MD80; so we reset the speeds and the flaps back to the original numbers. When our turn came the tower instructed us to line up and wait and said that it would be 2 minutes for wake turbulence for a heavy landing on the crossing runway. As I started to move forward; the Tower then issued an immediate takeoff clearance with crossing traffic on a two mile final and I rushed.As has been said many times; don't let ATC rush you! I allowed external distractions to overwhelm me for a few minutes. I should have stuck with normal thrust and not tried to reset back to flex thrust. And I should not have accepted the immediate takeoff clearance.

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.

Attributes
ACN	1470045
Time
Date	201708
Local Time Of Day	1801-2400
Place
Locale Reference	ORD.Airport
State Reference	IL
Environment
Light	Night
Aircraft 1
Make Model Name	Regional Jet 700 ER/LR (CRJ700)
Operating Under FAR Part	Part 121
Flight Phase	Takeoff
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Deviation - Procedural FAR Deviation - Procedural Published Material / Policy

CRJ700 flight crew and flight attendant reported changes to their takeoff clearance distracted the flight crew and caused them to takeoff before completing checklists and alerting the flight attendants.