EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Returned To Gate; Flight Crew Rejected Takeoff
Aircraft; Human Factors
After we received takeoff clearance from Tower and completed the before takeoff checklist; the Captain (pilot flying) proceeded to bring the thrust levers to the takeoff detent and begin the takeoff roll. A few seconds after the engines were verified stabilized at takeoff thrust (3-5 seconds approximately) the EICAS displayed a magenta MAIN CABIN DOOR OPEN warning and EMERG LT NOT ARMED caution messages along with the associated aural bells. The Captain subsequently called for an aborted takeoff and brought the thrust levers to idle and began braking. I made a PA to the cabin to remain seated; declared the aborted takeoff to the Tower and completed the rejected takeoff checklist once we were clear of the runway and the Captain requested it. Company policies and procedures were executed; as they should have been.
EMB145 crew rejected their takeoff when EICAS displays MAIN CABIN DOOR OPEN warning and EMERG LT NOT ARMED caution messages.