Date: 201510
Local time of day: 1801-2400
Location: PDX.Airport, OR
Flight conditions: VMC
Light: Daylight
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower PDX
Second aircraft: Caravan 208B
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown
Second reporter function: Local
Anomaly: Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: We apparently took off Runway 28R without clearance. On the ATIS; it stated TWR FREQ ALL RWYS 123.77. We pushed back and taxied out without any incident; all was normal. As we approached Runway 28R we switched to Tower frequency on 123.77. There are two Tower frequencies; but they were only using 123.77 as it said on the ATIS. There were other aircraft landing on 28R as Runway 28L was closed. We noticed that we couldn't hear all of the other flights that were taxiing and landing. I believe we did hear some of them; but not all. We were told to line up and wait 28R by Tower and I read it back. The Captain taxied us out into position. The next call we heard was fly runway heading; cleared for takeoff 28R. We transferred the controls and I took off. When we were airborne; Tower contacted us and told us that we took off without a clearance; that she cleared another aircraft to takeoff on Runway 21; and that we took that clearance instead. She also said that she tried to call us back many times to stop our takeoff that the clearance wasn't for us. Neither of us heard anything from the Tower telling us to stop; or that we had read back someone else's clearance. Tower then gave us a phone number to call when we landed and switched us to Departure. The rest of the flight went without incident.We could have verified that the takeoff clearance was for us. We could have also queried Tower if they had switched Tower frequencies from what was on the ATIS since we couldn't hear all of the other aircraft.


Second narrative: An aircraft had just landed Rwy28R and I put a B737 in position. I then told the aircraft rolling out to turn left at T and contact ground .9. While he was exiting; I told a C208 cleared for takeoff RWY21 runway heading. The B737 crew took the takeoff clearance and started to roll. I told the B737 negative negative; that clearance was not for them; hold in position. I then went back to the C208 and cleared him for takeoff on RWY21 runway heading. I went back to the B737 who was still rolling and again advised him to hold in position. The landing B737 was in the turn when the departing B737 took the clearance; but it was too early in my opinion to clear them for take-off. I reached out to the landing B737 to verify that the aircraft was taxiing straight ahead and to again contact ground to ensure that the aircraft was clear of the runway since the departing B737 was not responding to my calls. Another aircraft checked on final for RWY28R. I cleared them to land. The departing B737 was off the departure end airborne when I did a radio check to ensure that he could hear me. He responded; and I advised him that the takeoff clearance was not for him and to contact PDX tower when they reached their destination. I advised that I had the phone number when he was ready to copy. He said he was ready. I told him possible pilot deviation and gave the number for the tower. I then switched the C208 to departure; and then the B737 to departure. Realizing that the B737 crew had taken the C208's takeoff clearance; I checked in with departure to make sure that the B737 crew was on the SID that he was filed for; as he was most likely flying runway heading and not the WHAMY SID that he filed. Recommend that the airlines listen to what is being issued and if they aren't sure to ask before they take a random clearance.


Synopsis: A Tower Controller and the two B737 pilots involved describe a takeoff without clearance from PDX. The B737 crew took the clearance for another flight and failed to respond when the Tower attempted to stop them.