DALLAS, TX, USA
N675AA
BOEING 737-3A4
N31DB
CESSNA 401
THE CESSNA 401, N31DB, HAD BEEN CLEARED TO TAXI FOR TAKEOFF ON RUNWAY 13L, AND REPORTED HAVING THE BOEING 737, N675AA, IN SIGHT. AFTER TURNING NORTHWEST ONTO TAXIWAY BRAVO, THE CESSNA CAPTAIN LOST SIGHT OF THE 737. THE CESSNA FIRST OFFICER WAS OCCUPIED WITH DUTIES INSIDE THE COCKPIT AND DID NOT SEE THE 737 UNTIL IMMEDIATELY BEFORE THE COLLISION. AFTER LANDING ON RUNWAY 13L, THE 737 EXITED THE RUNWAY, RECEIVED AND ACKNOWLEDGED CLEARANCE TO TAXI TO THE GATE, BUT DID NOT ACKNOWLEDGE RECEIVING THE TRAFFIC ADVISORY CONCERNING THE CESSNA TO HIS LEFT. THE 737 PROCEEDED TO TAXI NORTHWEST ON TAXIWAY MIKE. THE COLLISION OCCURRED AS THE 737 MERGED FROM MIKE ONTO BRAVO. THE 737 CREW STATED THEY NEVER SAW THE CESSNA. WITNESSES OBSERVED THE AIRPLANES TAXIING PARALLEL TO ONE ANOTHER WITH THE 737 SLIGHTLY AHEAD OF THE CESSNA AND GRADUALLY CONVERGING UNTIL THE LEFT WING OF THE 737 IMPACTED THE RUDDER OF THE CESSNA. ALTHOUGH THE GROUND CONTROLLER 'ANTICIPATED' THAT THE 737 WOULD FOLLOW THE CESSNA, HE DID NOT ISSUE SPECIFIC SEQUENCING INSTRUCTIONS TO ENSURE THAT THIS TOOK PLACE.
HISTORY OF FLIGHT On July 28, 1995, at 0737 central daylight time, a Boeing 737- 3A4, N675AA, collided with a Cessna 401, N31DB, while both airplanes were taxiing at Love Field, Dallas, Texas. The Boeing was operating under Title 14 CFR Part 121 as Southwest Airlines Flight 5, scheduled service from Amarillo, Texas, to Dallas. The Cessna was operating under Title 14 CFR Part 135 as Raven Air 31, a non-scheduled cargo flight from Dallas to Tyler, Texas. The Boeing sustained minor damage and the Cessna was substantially damaged. There were no injuries to Raven Air's commercially rated captain and first officer or to Southwest's five crew members and 92 passengers. Visual meteorological conditions prevailed. At 0736:04, the Cessna received clearance from ground control to taxi from the Dalfort ramp to runway 13L and was advised of "the Boeing clearing that runway." The Cessna acknowledged having the Boeing 737 in sight and taxied from the ramp onto taxiway Bravo. After exiting runway 13L, at 0736:31, the 737 received clearance from ground control to taxi to parking and was advised of "traffic ahead to your left, twin Cessna outbound from Dalfort." The 737 responded with "into parking, Southwest five," and proceeded to taxi northwest on taxiway Mike. There was no further activity on the ground control frequency until 0737:21 when the Cessna transmitted "that 737 just hit us." Witness statements were submitted by six witnesses who observed the collision. Two witnesses (both passengers on the 737) described the Cessna and the 737 as moving in the same direction and at the same speed. Three witnesses reported the two aircraft were merging/converging with the Cessna's right wing tip slightly ahead of the 737's left wing tip. Four witnesses observed the leading edge of the 737's left wing contact the rudder of the Cessna. All six witnesses reported that, immediately following the impact, the Cessna made a sharp left turn of approximately 360 degrees before coming to a stop. They further reported that the 737 continued straight ahead for a "short" distance before coming to a stop. The captain of the Cessna reported in his written statement that, after intercepting taxiway Bravo, he "lost visual contact with the 737 due to my position on the taxiway." During an interview, he recalled observing the 737 while on taxiway Bravo by looking back over his right shoulder through the Cessna's right forward cabin window. The first officer of the Cessna was occupied with duties inside the cockpit during the taxi, and did not see the 737 until immediately prior to the collision. When the captain of the Cessna heard engine noise, he realized he was hearing the 737 and "added power trying to speed up." He felt the collision and applied left rudder, performing a 360 degree turn before coming to a stop. The captain and first officer of the 737 reported that they did not recall hearing any traffic advisories from ground control. Neither recalled seeing any general aviation aircraft that might be a hazard to their taxiing. Just after turning left off taxiway Mike to join Bravo, the captain of the 737 felt a "push" on his airplane. Seconds later he heard a radio transmission stating "the 737 just hit us." Realizing that the communication referred to his aircraft, the 737 captain stopped his aircraft. After ground personnel examined the 737 and found no damage or leaking fluids, the 737 contacted ground control, received clearance and taxied to the gate. After the 737 was parked at the gate, a passenger came forward and identified himself to the crew as a witness. In his description of the event as recorded on the cockpit voice recorder (transcript attached), the passenger described the 737 as "overtaking" the Cessna and stated that the leaded edge of the 737 "clipped" the Cessna. COMMUNICATIONS A transcript is attached of the transmissions on the Love Field Air Traffic Control Tower local and ground control frequencies during the time periods pertinent to the accident. On August 3, 1995, the controller who was working the ground control position at the time of the accident was interviewed by the investigator- in-charge. Representatives of all parties to the investigation were also present at the interview. In response to questions, the controller provided the following information. He came on duty at 0630. He was acting as the controller- in-charge. Approximately 0727, he relieved the ground controller. Also present in the tower and working their respective positions were three other controllers: local, radar, and clearance delivery. He considered the traffic to be minimal. Prior to the accident, airport operations personnel were in the process of closing runway 13R. He was coordinating the closure with FAA maintenance and airport operations. The local controller was coordinating on the land-line concerning arrivals being handled by regional approach. Approximately 0736, Raven 31 called to request taxi instructions from the Dalfort FBO. He instructed the pilot to taxi to runway 13L and issued traffic advisories about a Boeing 737 (Southwest 5) clearing runway 13L and a Baron taxiing in the opposite direction on the inboard taxiway (taxiway B.) Raven 31 reported both aircraft in sight and acknowledged the taxi instructions. He then issued a traffic advisory to the Baron about the opposite direction twin Cessna (Raven 31) and received an acknowledgment. Southwest 5 called for taxi instructions to gate 4C. He advised Southwest about the twin Cessna traffic outbound from Dalfort and instructed the pilot to taxi into parking. Southwest 5 acknowledged. Once he heard verbal acknowledgment from both aircraft he had "anticipation of separation." There was a large separation between the airplanes and he anticipated they would stay separated. In his mind, Raven was first and Southwest was following. He did not observe the actual taxiing of the two aircraft after issuing the taxi clearances. He diverted his attention to another duty, logging the closure of runway 13R in the facility log. While he was typing, he heard the pilots of both aircraft call ground control. Approximately 0738, he requested a transmission repeat. The pilot of Raven 31 stated that the 737 had just hit him. He saw the collision damage to Raven 31 and asked Southwest if they required any assistance. He then requested position relief and made the initial accident notification calls. AIRPORT INFORMATION Love Field has three runways, two of which are parallel, runway 13L/31R and runway 13R/31L. Taxiway Bravo is the main taxiway on the southwest side of runway 13L/31R. The Dalfort Aviation ramp is located southwest of runway 13L/31R, adjacent to taxiway Bravo. To the north of the Dalfort ramp, the centerline of taxiway Bravo curves towards runway 13L/31R to maintain clearance from a gate structure. (See attached diagram.) Taxiway Mike is the inner taxiway on the southwest side of runway 13L/31R. It runs parallel to runway 13L/31R and extends from taxiway Bravo 1 to Bravo 3. At Bravo 3, an aircraft proceeding northwest on the taxiway centerlines would turn 90 degrees left off Mike onto Bravo 3, and then turn 90 degrees right off Bravo 3 onto Bravo. Tower personnel reported aircraft heading northwest on Mike seldom follow these markings onto Bravo. The majority of aircraft take the same path as that used by the accident 737 and "cut the corner," turning left approximately 20 degrees from Mike directly onto Bravo. FLIGHT RECORDERS The Cessna 401 was not equipped with a cockpit voice recorder (CVR) or flight data recorder (FDR), nor was it required to be so equipped under current Federal Aviation Regulations. The Boeing 737 was equipped with a Fairchild Model A-100A CVR, S/N 60937. The attached CVR transcript begins at 0735:19 as the 737 was about to touch down on runway 13L and continues until 0756:39 after the aircraft was parked at the terminal gate. The traffic advisory made by ground control to the 737 at 0736:31 concerning the "twin Cessna outbound from Dalfort" was recorded by the CVR. Conversation between the crew concerning the quality of the landing appears on the transcript from 0736:59 to 0737:14. At 0737:17, a sound similar to an increase in reciprocating engine RPM was recorded by the cockpit area microphone. Following the collision, both the captain and first officer of the 737 made remarks indicating they had not seen the Cessna at any time during their taxi. The Boeing 737 was also equipped with an Allied Signal solid state FDR, S/N 0599. A printout of selected parameters is attached. The playback data revealed an impact signature in the longitudinal and vertical acceleration traces. Approximately 3 seconds after this signature, the airplane began to decelerate. At the time deceleration began, the airplane was traveling at a groundspeed of approximately 21 knots. The airplane traveled about 106 feet in the 3 seconds before deceleration began and an additional 179 feet from the time deceleration began until it came to a stop. WRECKAGE AND IMPACT INFORMATION A 2 foot section of the rudder from the Cessna 401 was located on the centerline of taxiway Bravo at the approximate location where an airplane merging from taxiway Mike would intercept taxiway Bravo. The Cessna 401 was located approximately 100 feet south of the rudder section on a heading of about 360 degrees. The vertical stabilizer was crushed to the right and forward and the rear portion of the right tip tank was bent outboard. The Boeing 737 sustained surface scratches to the left wing #2 leading edge slat and the upper and lower wing surfaces. A 12 inch wide band of scratches and green paint smears was located on the left engine inlet at the 3 o'clock position. ADDITIONAL INFORMATION The Cessna 401 was released to a representative of the owner on July 28, 1995, at the completion of the on scene investigation. The Boeing 737 was released to a representative of the owner on July 28, 1995, after it was examined at the operator's hangar. The CVR and DFDR from the 737 were returned to the operator after they were read out and the final wreckage release was signed on January 8, 1996.
FAILURE OF THE FLIGHTCREWS OF THE BOEING 737, N675AA, AND THE CESSNA 401, N31DB, TO SEE AND AVOID EACH OTHER. FACTORS WERE: THE FAILURE OF 737 FLIGHTCREW TO RESPOND TO THE TRAFFIC ADVISORY GIVEN BY THE GROUND CONTROLLER IDENTIFYING POTENTIALLY CONFLICTING TRAFFIC, AND THE FAILURE OF THE GROUND CONTROLLER TO ISSUE SEQUENCING INSTRUCTIONS TO BOTH AIRCRAFT.
Source: NTSB Aviation Accident Database
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