Air carrier first officer reported rejecting takeoff due to another aircraft crossing the runway.

Attributes
ACN	1553284
Time
Date	201806
Local Time Of Day	1801-2400
Place
Locale Reference	PHL.Airport
State Reference	PA
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	Medium Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Takeoff
Flight Plan	IFR
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument
Events
Anomaly	ATC Issue All Types Conflict Ground Conflict Critical

Narrative:

We rejected our takeoff at around 60 to 70 knots due to another airplane crossing the runway at a taxiway. The captain noticed the plane crossing the runway. We never heard any clearances to cross while we were holding on the runway. The clearance could have been issued on different frequency. We rejected the takeoff and contacted ATC. I suggest at least one person should always have their eyes outside the cockpit while moving.

Original NASA ASRS Text

Title: Air carrier First Officer reported rejecting takeoff due to another aircraft crossing the runway.

Narrative: We rejected our takeoff at around 60 to 70 knots due to another airplane crossing the runway at a taxiway. The Captain noticed the plane crossing the runway. We never heard any clearances to cross while we were holding on the runway. The clearance could have been issued on different frequency. We rejected the takeoff and contacted ATC. I suggest at least one person should always have their eyes outside the cockpit while moving.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.