Air carrier flight crew reported departing with an incorrect pack configuration.

Attributes
ACN	1765395
Time
Date	202010
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Taxi Takeoff
Flight Plan	IFR
Component
Aircraft Component	Air Conditioning and Pressurization Pack
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Experience	Flight Crew Last 90 Days 185 Flight Crew Total 8159 Flight Crew Type 5491
Person 2
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Instrument Flight Crew Multiengine
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy

Narrative:

Received aircraft from maintenance base in ZZZ with aft fuel boost pump MEL. Called and got another dispatcher to patch captain to maintenance control. Still did not get my answer about having to carry an extra 5;000 pounds of unusable fuel. Flying with a first officer who was on different aircraft. Very little recent experience in aircraft; because of the covid and personnel issues. Slowed pace considerably to accommodate; first officer [was] very hard on himself and working hard on flows; but not smooth and habit like. Dark on departure; and with amber fuel pump light shining in my eye; I did not catch the switch out of place after the before takeoff checklist was done and we took the runway for takeoff. Got the tattle tale message after takeoff and debriefed the situation.

Original NASA ASRS Text

Title: Air carrier flight crew reported departing with an incorrect pack configuration.

Narrative: Received aircraft from maintenance base in ZZZ with AFT FUEL BOOST PUMP MEL. Called and got another Dispatcher to patch Captain to Maintenance Control. Still did not get my answer about having to carry an extra 5;000 pounds of unusable fuel. Flying with a First Officer who was on different aircraft. Very little recent experience in aircraft; because of the COVID and personnel issues. Slowed pace considerably to accommodate; First Officer [was] very hard on himself and working hard on flows; but not smooth and habit like. Dark on departure; and with amber fuel pump light shining in my eye; I did not catch the switch out of place after the Before Takeoff Checklist was done and we took the runway for takeoff. Got the tattle tale message after takeoff and debriefed the situation.

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.