HISTORY OF FLIGHT On November 30, 2004, at 0608 eastern standard time, a Mitsubishi MU-2B-60, N941MA, operated by Epps Air Service Inc., sustained substantial damage when it collided with an aircraft tug, during takeoff from the Philadelphia International Airport (PHL), Philadelphia, Pennsylvania. The airline transport pilot, the tug driver, and two additional ground personnel were not injured. An instrument flight rules (IFR) flight plan had been filed for the flight that was destined for the Teterboro Airport (TEB), Teterboro, New Jersey. Night visual meteorological conditions prevailed for the flight that was conducted under 14 CFR Part 135. According to recorded voice communications, the pilot of the MU-2 contacted the PHL ground controller (GC), at 0602, and advised, "eps one oh eight atlantic ready to taxi kilo." The GC replied, "…give way to the lear jet outbound and taxi to three five at kilo." The pilot acknowledged the transmission and at 0603, the GC advised, "one oh eight you can cross runway two six." The pilot also acknowledged this transmission. According to the pilot, the airplane was parked at the Atlantic Aviation ramp, which was located on the northeast side of the airport, known as the south apron. Once he was cleared to taxi, he taxied to runway 35 via taxiway A, taxiway D, across runway 26, to taxiway K. At 0603, "Delta Airlines maintenance tug 987," contacted the GC and advised, "I'm on the south ramp by atlantic aviation. I'd like to relocate under tow to echo one." The GC replied, "…give way to the m u two that's coming out of atlantic…proceed as requested and cross runway three five go to spot eleven and call ramp control there." The operator of tug 987 replied, "…cross three five at spot eleven I'll call ramp control thank you." Tug 987 was towing a MD-80 airplane and was enroute to the US Airways ramp, located on the west side of runway 35. A "brake rider," was positioned in the MD-80 and in communications with the GC controller. The "brake rider" relayed instructions, received from the GC controller to the tug driver via the radio. According to the "brake rider," the MU-2 passed in front of the tug on the south ramp enroute to runway 35. After the airplane passed, the tug driver exited the south apron and proceeded via taxiway A, taxiway D, and then a left turn onto taxiway G. As the tug approached runway 35 on taxiway G, the driver radioed the "brake rider," and asked if they should hold short of the runway. The "brake rider" replied, "no, we have clearance all the way to spot eleven." The tug driver then continued onto runway 35. At 0605, the pilot of the MU-2 contacted the local controller (LCE) and advised, "…ready three five kilo." The LCE replied, "Epps one zero eight runway three five intersection kilo maintain four thousand and you're cleared for takeoff." The pilot acknowledged the clearance; however; approximately one minute later, the LCE cancelled the takeoff clearance because he noticed another airplane on the radar, descending from 4,000 feet, moving left to right, off the departure end of the runway. At 0607, the pilot reported, "we have him in sight," and the local controller responded, "okay, maintain visual separation with that traffic turn left to two nine zero maintain four thousand and you're cleared for takeoff." The pilot acknowledged the takeoff clearance. According to the pilot of the MU-2, he initiated a takeoff from runway 35, at intersection "Kilo." During his takeoff roll, at 80 knots, he checked his engine instruments, and reconfirmed visual separation with airborne traffic off the departure end of the runway. As he looked back down the runway, he observed an aircraft tug at the centerline, moving right to left. The pilot then aborted the takeoff, applying maximum braking and reverse thrust. He attempted to maneuver the airplane to the left side of the runway toward the grass; however, the airplane contacted the tug at the intersection of runway 35 and taxiways "Golf" and "Echo." The "brake rider" in the MD-80 reported that as the tug was approximately three-forths across the runway, he observed the landing lights of the MU-2 moving towards them on the runway. When he realized the airplane was not going to stop, he instructed the tug driver to, "Stop, stop, stop!" The airplane's right wingtip then impacted the tug cab and the MD-80 rolled forward for several seconds before coming to rest, just off the taxiway, in a grass area. WRECKAGE EXAMINATION Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed the right wing tip fuel tank separated from the right wing and came to rest inside the tug cab. The right wing structure sustained substantial damage, and "bald spots" were observed on the landing gear tires. No damage was observed to the MD-80. AIR TRAFFIC CONTROL Facility Operations At the time of the accident, three full performance level controllers were working in the tower cab, in the Local Control East (LCE), Ground Control (GC), and Clearance Delivery (CD) positions. The LCE and GC positions were located next to each other in the northeast corner of the tower cab. Controller Interviews The airplane's taxi route to runway 35 required that the airplane cross runway 26. The LCE reported that he thought the GC had coordinated the airplane's runway crossing clearance with him; however, could not remember. The LCE did not recall receiving a request from the GC, to allow the tug to cross runway 35 at taxiway "Echo - four." The GC stated that he believed he coordinated the tug crossing with the LCE, but was unsure. The CD controller reported she did not hear any verbal coordination between the GC and LCE controllers to cross the active runway. A review of recorded voice communications revealed no evidence of the crossing coordination between the controllers. Manual Requirements Philadelphia Tower Notice 7110.33, effective January 17, 2003, stated in part "all runway crossing authorization and runway crossing complete coordination shall be accomplished via a recorded landline. The request to cross the runway may be recorded off landline." Additionally, FAA Order 7110.65, "Air Traffic Control," paragraph 3 - Use of Active Runways, stated in part, "the ground controller must obtain approval from the local controller before authorizing an aircraft or a vehicle to cross or use any portion of an active runway."