OPS16IA008

On April 7, 2016 at 1836 central daylight time, a runway incursion occurred on runway 35L at Dallas-Fort Worth International Airport (DFW), Dallas, Texas, when a Boeing 737-800, N896NN, was on takeoff roll while an Embraer 505, N304QS, crossed the runway downfield. The closest proximity between the two airplanes was approximately 2,800 feet when the speed of the Boeing was about 120 knots. The Boeing 737-800 was operated by American Airlines as flight 2408, under the provisions of 14 Code of Federal Regulations Part 121 as a regularly scheduled passenger flight (AAL2408). The Embraer 505 was operated by NetJets Aviation under the provisions of 14 Code of Federal Regulations Part 91K as a fractional ownership flight (EJA304). Visual meteorological conditions prevailed and there were no injuries to the passengers or crew of either flight. EJA304 had landed on runway 35C and was instructed by the LE1 controller to taxi to the terminal via taxiway M and K8. At 1834:20 the pilot of EJA304 was directed to hold short of runway 35L on taxiway K8. An MD-82, AAL2256, was holding short of runway 35L at taxiway EK, and an E170, ENY3192 taxiing to the gate after landing, was instructed to taxi via taxiway M to taxiway EJ and to hold short of runway 35L. At 1835:14, the LE1 controller cleared a flight (AAL2304) for takeoff on runway 35L and eight seconds later, at 1835:22, instructed the pilot of AAL2408 to LUAW on runway 35L. At 1835:39, the pilot of SKW5432, an arriving CRJ7 regional jet, reported outside the JOBBS airspace fix for landing runway 35C. The LE1 controller responded "Skywest fifty-four thirty-two, DFW tower, wind zero two zero at one five gusts two zero, runway three five left, cleared for takeoff". The pilot of SKW5432 did not respond however, the pilot of AAL2408, in position at the approach end of runway 35L, responded with "American twenty-four oh eight cleared for takeoff three five left". The LE1 controller did not respond to the incorrect readback by the pilot of AAL2408. As the previous departure (AAL2304) passed the taxiways intersecting runway 35L where aircraft were holding, the LE1 controller, in successive progression, directed the pilots of EJA304, AAL2256, and ENY3192 to cross runway 35L. All three pilots acknowledged the crossing clearance. As AAL2408 began its takeoff roll the Runway Status Lights (RWSLs) on runway 35L activated illuminating the Runway Entrance Lights (RELs) at the hold short locations of the three aircraft that had just been instructed to cross runway 35L, as well as the Takeoff Hold Lights (THLs) at the approach end of the runway. The RELs provided a visual signal to the pilots holding short of runway 35L. The THLs provided a visual signal to the pilot of AAL2408 that the runway was occupied however, data indicate that AAL2408 had progressed too far down the runway to observe the THLs by the time they had illuminated. Of the three aircraft holding short of runway 35L, only EJA304 proceeded across runway 35Lwith AAL2408 departing the same runway. After takeoff but before switching to departure control, the pilot of AAL2408 commented to the LE1 controller about the business jet that was on the runway as he departed. As EJA304 cleared runway 35L, the ASDE-X indicated AAL2408's speed to be 120 knots and the closest proximity between the two aircraft was approximately 2,800 feet. The ASDE-X did not alarm. During a System Service Review after the event, controllers identified a recent procedural change that required additional verbiage when issuing crossing instructions, and an increased speech rate associated with increased workload.