Date: 201506
Local time of day: 0001-0600
Location: DFW.Airport, TX
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower DFW
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Communication Breakdown
Second reporter function: Pilot Flying; Captain
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: While holding short of RW 17R for departure I hear the controller clear [our flight number] to line up and wait -- I read back line up and wait. We taxied into position and then another flight; [with a similar call sign] asked the tower if that line up and wait was for them or us ... tower asked who was on the RW; I answered [with our flight number]; then the tower cleared us for TO. On our TO roll; [similar call sign] asks the tower if the original line up and wait had been for them; and the tower said yes.A contributing factor in my mind was that as we approached the ramp area for 17R departures; and weather was in the area (lots of rain) the ground controller had several flights go to clearance to get reroutes -- and cleared them to the end of the ramp (full length) but had us take the shorter route KEG .... Because of this I had the expectation that we would probably be going straight out without a reroute delay; while the other flights were being delayed. So when we approached the hold short line and the tower called for [us] to line up and wait; even though there were other flights waiting I thought that they were holding because of the weather; so it made perfect sense that we would be going out immediately. I still believe the tower cleared us to line up and wait -- but regardless I definitely read back [our flight number] and she missed it if in fact the original call was for [the other flight].Three things that I can immediately think of to help reduce incidences like this from happening 1)  Crew members should be careful about the expectations they have about what is going on - and be very vigilant about call sign usage; especially near the RW.2) ATC should be more careful at DFW about the call signs -- we have all heard many times when they call a very similar but incorrect call sign -- some crew member's answer and correct them; others just do not answer.3) The company should have a review process that checks the marketing schedules and flight numbers for similar flight numbers -- I know they like to keep similar series numbers for certain markets to make it easy; but having a four digit flight number with only the last digit different should be avoided.


Second narrative: First and foremost too many of [company]'s call signs are very similar during different phases of flight. Seems at least once a day when on duty whether it is on the ground or in the air I hear confusion over call signs concerning queries; taking others clearances; taking the wrong frequency etc. And a good portion of these occurrences are due to similar call signs; both [company] and industry wide. Personally I think that [company] needs to review their procedures for naming flight call signs that are similar when flying at the same time. In our case I am not sure why it took so long for [the other flight] to query tower on the clearance but good on them for eventually doing so. I would also like to think had we gotten to the takeoff clearance portion of flight that we would have caught the differences in call signs.


Synopsis: Air carrier flight crew reported a runway incursion when they took a clearance intended for another aircraft with a similar call sign.