What happened
During a period of active operations under Plan X, which utilized both runways 4 and 9 for landings and departures, a conflict occurred between two departing aircraft. A Lufthansa A319, flight DLH437, was instructed to taxi into position and hold on runway 4L while waiting for a previous arrival to vacate the runway. Simultaneously, a Chautaucal Airways E145, flight CHQ7826, was instructed to taxi into position and hold on runway 9L, with the controller advising that DLH437 would be departing from runway 4L.
Once the preceding arrival exited the runway, DLH437 was cleared for takeoff. Approximately thirty-five seconds later, a developmental controller cleared CHQ7826 for takeoff on runway 9L. The Local Monitor and the Certified Professional Controller (CPC) did not hear the clearance issued to the E145. Shortly after the clearances were issued, the Local Monitor observed both aircraft rolling toward the intersection of the runways. The North Local Controller immediately canceled the takeoff instructions for both aircraft.
The two aircraft reached a closest proximity of 100 feet before coming to a stop at the runway intersection. The pilot of DLH437 later reported that they observed the E145 and were in the process of aborting their takeoff when the controller issued the stop command.
The investigation
The investigation examined the actions of the developmental controller and the oversight provided by the CPC. It was noted that the AMASS system did not trigger an alarm because it lacked the specific crossing runway logic required to detect this type of conflict.