Caravan 208B
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Commercial
Flight Crew Last 90 Days 75; Flight Crew Total 1300; Flight Crew Type 310
Communication Breakdown; Situational Awareness
ATC Issue All Types; Conflict NMAC; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Human Factors
I heard Tower clear me for takeoff [and] I read back instructions. On the takeoff roll Tower instructed me to make left turn; as I began the turn I saw [an air carrier aircraft] on the converging runway taking off. [I] turned to avoid; as Tower told me I was not cleared to takeoff.
There were at least three causes for this event:1) While taxiing the PIC was quietly verbalizing the pre-takeoff checklist; and it was during this time that we thought we heard the clearance. 2) When the PIC read back the clearance as: '[flight number] cleared for takeoff;' the Tower did not correct him. 3) The [air carrier] flight number was similar [to our flight number].A recurrence can be prevented by more clearly reading back a clearance when in doubt; by not accepting takeoff clearances until after the pre-takeoff checklist has been completed; and by the Tower listening closer to readbacks.
C208B flight crew reported a NMAC shortly after takeoff when they took a takeoff clearance meant for another aircraft with a similar call sign.