Date: 201509
Local time of day: 0601-1200
Location: IAH.Airport, TX
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Other Rejected Takeoff
ATC / advisory: Tower IAH
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Less Severe; Ground Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: Other takeoff roll
Result: Flight Crew Rejected Takeoff
Contributing factors: Environment - Non Weather Related; Aircraft
Primary problem: Aircraft

Narrative: While waiting in line for takeoff; we overheard a departing aircraft ask ATC if they saw any lights; and the controller responded by saying he didn't. The pilot stated that it must have just been a reflection. The Captain (CA) and I didn't pay much attention to that exchange because we were running our Before Takeoff Checklist above the line. ATC instructed us to line up and wait on Runway 15L. After a brief delay; ATC cleared us for takeoff. We completed the Before Takeoff Checklist below the line; and the CA advanced the thrust levers since he was PF on this leg. The CA stated; 'Set thrust' and I observed that the thrust was stabilized on the EICAS and responded by stating; 'Thrust set; XX.X percent'. I briefly looked outside the aircraft and returned my focus to the instrument panel.The CA then called; 'Abort; abort; abort.' As I looked outside the aircraft; I realized that the Runway Status Lights (RSL) had activated and were illuminating red. We had maybe only reached 40kts when we initiated the abort. The CA decelerated the aircraft while I notified ATC and made a PA to remain seated. We exited the runway onto taxiway WD and completed our memory items and the immediate action checklist. ATC asked why we aborted the takeoff and we informed him of the RSL activation. He stated that there was no conflict on the runway and there was no traffic that should have activated it. He said that it must have been a system error.ATC instructed us to taxi back to RWY 15L via WA. We completed all checklists and prepared for our next takeoff attempt. ATC instructed us to line up and wait; and a short time later cleared us for takeoff. This takeoff was completed normally and we continued our flight.We had just dealt with a mechanical issue after pushing off the gate. Due to the time it took to coordinate everything; we needed to perform a gate return in order to upload more fuel. I don't think that any of that was necessarily a threat; but I think it somewhat relevant since we had already been dealing with a few issues on this leg.I can't think of any errors we made while handling this aborted takeoff. The crew interacted well; communicated effectively; and followed procedures accurately. The only error that comes to mind is the internal system error that may have accidentally triggered the RSL to activate during our takeoff roll.Looking back; I'm curious if the previous airplane was asking ATC about the RSL activation during their takeoff roll. It's possible that they may have illuminated on that aircraft too; but they maybe only flickered or caught a brief glimpse of it before taking off. That may explain the brief discussion we partially overheard. As far as my behaviors are concerned; I can't think of anything that I should have done differently. This event does; however; serve as a good reinforcement that staying on top of memory items and limitations is important to the safe conduct of each and every flight.




Synopsis: An EMB-145XR First Officer reported they rejected the takeoff at IAH when the Runway Status Light (RSL) system activated.