Date: 202007
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Distraction; Communication Breakdown
Second reporter function: Captain; Pilot Flying
Anomaly: Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert
Contributing factors: Environment - Non Weather Related; Human Factors
Primary problem: Human Factors

Narrative: Captain's takeoff. We were cleared to taxi to Runway XXR via Bravo. We ran our checklist 'to the line.' We were pushed to Tower frequency. Tower contacted us and gave us the option for an intersection takeoff at Foxtrot or full length; Runway XXR; lineup and wait. We still had a long taxi to get the hold short of Runway XXR. We continued to taxi; we ran the 'below the line' items remaining on the Before Takeoff checklist. We entered Runway XXR at the full length. The Captain pushed up the throttles and started our takeoff roll. We went through our normal callouts and rotated. A short time after we were airborne; the Tower Controller contacted us that we had not been given clearance for takeoff. I thought we had been given clearance for takeoff on our taxi which was not the case. [Cause was] complacency. Expectation bias (at some moment; we were going to be given clearance to takeoff on our long taxi?). Mounds of external stressors that are distracting (COVID-19; upcoming furloughs; possibly being displaced to a new base due to company downsizing). Those external stressors seemed to be at the forefront due to the long quiet taxi to XXR and inactivity and lack of operations at ZZZ due to decimation of the industry. When I am busy; I am acutely more aware of my SA. To combat complacency; I will make a concerted effort to tune into my SA and strict adherence to SOPs. One thing I believe in and live by is to NOT worry about things out of my control. I let that slip for a few seconds and it cost us severely. All the external factors I mentioned above are out of my control therefore I will get back to compartmentalizing them. There is nothing I can do about them. The only thing that is within my control at that moment in time is the operation of that aircraft. To help combat Expectation Bias; I have already made a mechanical change to ensure we receive takeoff clearance. I have started to press the chrono button on the panel that starts the clock when takeoff or landing clearance is received. If that clock is not started; I will be asking the CA and tower for clearance or to verify clearance. I have also written on my checklist; on the bottom of the 'Before Takeoff' 'takeoff clearance?' I believe these changes will prevent any further miscues.


Second narrative: Cleared to taxi out to Runway XXR. On taxi out completed taxi check list to the line. Switched to Tower and given the option for an intersection or full length departure. We took full length. Was given clearance onto the runway very early on the taxi. Completed below the line check list. Took the runway and departed. On climb out was informed that we had taken off without a takeoff clearance.[Causes include] being cleared onto the runway very early; very quiet day. Being somewhat distracted by COVID and the state of the Airline. Assumptions. We thought we were cleared for takeoff.Be more vigilant; block outside distractions; don't assume.


Synopsis: Air carrier flight crew reported taking off without a clearance and stated that being distracted by the COVID-19 pandemic and the state of the airline contributed to the event.