EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Human-Machine Interface; Confusion
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Air Traffic Control Issued New Clearance
Human Factors; Procedure; ATC Equipment / Nav Facility / Buildings
Air Carrier X had just landed Runway 19 in DCA. We were cleared to line up and wait. Air Carrier X was exiting the runway and we were cleared for take off. As soon as we could visually see Air Carrier X was clear of Runway 19 we started to depart. For whatever reason; Air Carrier X decided to stop immediately after their aircraft cleared the runway however it was still showing an alert on the ground surveillance RADAR in ATC because they did not pull off far enough. ATC told us to abort take off; but we were already at V1 and had insufficient runway to reject the take off. We continued without incident and there was never any question on separation. When we landed; I spoke to the Tower Supervisor who indicated that it was not our fault in anyway. He also stated that they had the separation with Air Carrier X and they believe it was a malfunction of the electronic runway incursion system. ATC should make sure that all aircraft pull completely off the active runway before issuing a take off clearance.
[Narrative 2 contains no additional information.]
Air Carrier departure from DCA elected to continue take off because of V1 speed even though an abort instruction was issued by ATC because of a slow exiting previous landing aircraft.