MD-83
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
ATC Issue All Types; Conflict Ground Conflict; Critical
Flight Crew Took Evasive Action
Human Factors; Procedure
We had just landed on [Runway] 25L in Las Vegas. As I transferred control to the Captain we heard ATC instructions which we believed instructed us to exit Taxiway A6 and cross [Runway] 25R. I repeated the instructions to ATC. As we were approaching the 25R hold short line; I observed that a B737 was still holding short of 25R and partly blocking my full view of the runway. I got a little suspicious when I saw that the B737 was still holding there and took a closer look down the runway of 25R. It was then that I saw another B737 just rotating off the runway. I didn't have time to say anything. I just slammed hard on the brakes and the Captain joined me on the brakes. We did come to a stop just short of the hold short line. No part of the aircraft crossed the runway. After returning to the gate we contacted the Tower for further explanation. The Captain spoke to the Tower Supervisor. He replayed the tapes and his response was that Tower Controller told us to hold short. The Tower Supervisor said they did not clearly understand my response. The Captain and I both believe we heard a clearance to cross Runway 25R. However; if I had read back the clearance instructions incorrectly there was no response from Air Traffic Control to correct it. I do not believe there were any passengers injured from the sudden braking. However; Captain made a follow-up PA to the passengers.There was clearly a miscommunication between us and Air Traffic Control. However; I think there are some lessons to learn from this incident. We have to remind ourselves not to respond to ATC while still decelerating after the landing phase. I think if we had waited until we were completely off the runway before responding to ATC; then there would be less chance of miscommunication.
MD83 First Officer reported landing at LAS on Runway 25L and hearing a clearance to cross Runway 25R at A6 during deceleration with reverser's deployed. This was not correct and at the last moment an aircraft departing on Runway 25R was detected. Hard braking was employed to avoid crossing the hold short line.