RENO, NV, USA
N954AS
MCDONNELL DOUGLAS MD-82
ALASKA AIRLINES FLIGHT 601 (ASA601), N954AS, WAS ON A STANDARD INSTRUMENT DEPARTURE WHEN IT NEARLY COLLIDED WITH A MOONEY M20C, N91Y. THE MOONEY WAS TRANSITING THE RENO AIRSPACE AT 12,500 FEET MSL AND HAD JUST BEEN HANDED OFF FROM THE TRACON DEPARTURE CONTROLLER TO THE ARRIVAL CONTROLLER. THE LOCAL CONTROLLER DID NOT INFORM ASA601 TO CONTACT DEPARTURE CONTROL AFTER TAKEOFF. DURING ASA601'S INITIAL CLIMB, THE DEPARTURE CONTROLLER/AREA MANAGER LEFT HIS POSITION TO ANSWER A PHONE CALL FROM A FACILITY TECHNICIAN TO DISCUSS TRACON BUSINESS. AT THE SAME TIME, THE ARRIVAL CONTROLLER WAS TELLING THE MOONEY TO CHANGE TRANSPONDER CODES IN PREPARATION FOR A HANDOFF TO CENTER; AT THAT TIME, THERE WAS SOME CONFUSION BETWEEN THE MOONEY PILOT AND THE CONTROLLER ABOUT THE TRANSPONDER CODE. THE ARRIVAL CONTROLLER SAID HE DID NOT SEE THE DATA BLOCK FOR ASA601 BECAUSE HIS ATTENTION WAS DIVERTED TO THE MOONEY. THE CHANGING OF THE TRANSPONDER CODE AND THE MOONEY'S INTERMITTENT MODE C TRANSPONDER KEPT ASA601'S TCAS SYSTEM FROM ACQUIRING THE MOONEY. AFTER HIS PHONE CALL, THE DEPARTURE CONTROLLER TRIED TO CALL ASA601, BUT WITHOUT SUCCESS. HE THEN CALLED THE LOCAL CONTROLLER AND WAS INFORMED OF THE NEAR COLLISION.
HISTORY OF FLIGHT On August 19, 1994, at 1104 hours Pacific daylight time, a McDonnell-Douglas MD-82, N954AS, nearly collided with a Mooney M-20C, N91Y, near Reno Tahoe International Airport, Reno, Nevada. N954AS was operating as Alaska Airlines flight 601 (ASA601), a scheduled domestic passenger flight from Reno to Seattle, Washington, climbing to an assigned altitude of 15,000 feet msl. Four passengers and two flight attendants aboard ASA601 sustained minor injuries during the evasive action initiated by the flightcrew. Visual meteorological conditions prevailed. Both airplanes were receiving air traffic control services from radar controllers at the Reno Terminal Radar Approach Control (TRACON) at the time of the incident. The Mooney had an intermittent transponder with Mode C altitude encoding; however, it was not functioning properly at the time of the incident. According to the ASA601 flightcrew, no TCAS traffic or resolution advisory was received before the incident. During the investigation, an Air Traffic Control (ATC) Group was formed by an air traffic specialist from the National Transportation Safety Board's headquarters staff. Interviews of Federal Aviation Administration (FAA) ATC personnel involved in this incident were conducted by the ATC Group on August 31, 1994. In addition, telephone interviews were conducted with the Alaska Airlines flightcrew and the pilot of the Mooney M-20C. The complete ATC Group Chairman's factual report is attached to this report as an exhibit. N91Y was operating on a visual flight rules personal flight to Sacramento, California, and was flying at a pilot reported altitude of 12,500 feet. The certificated private pilot, the sole occupant aboard N91Y, was not injured. The flight originated at Elko, Nevada, at an undetermined time. At 1053:07, the pilot of N91Y initially contacted the departure radar controller at the Reno TRACON. At 1053:21, the departure controller was advised by the tower, "alaska six oh one on mustang and we're cc's (cab coordinator position) closed." The radar controller acknowledged the call from the tower and then transmitted, "ending in yankee say again." At 1055:18, the pilot of N91Y advised, "november niner one yankee mooney twelve thousand five hundred inbound from fernley." At 1055:24, the pilot was instructed to "squawk zero four six seven." After some confusion about the transponder code, at 1057:33, the pilot of N91Y was advised, "mooney niner one yankee radar contact two zero miles northeast of reno airport not receiving your mode c squawk altitude please." At 1057:39, the pilot advised, "ah roger we're level at twelve five." Following this transmission, the radar controller also determined that the pilot's destination was Sacramento. After receiving clearance to push back and taxi at 1057:24, ASA601 was cleared into position on runway 16L, then cleared for takeoff by the local controller at 1058:15. ASA601 acknowledged the takeoff clearance at 1058:22. Review of the air-to-ground communications transcripts revealed that the local controller did not instruct ASA601 to contact departure control until 1104:13, just after the flightcrew inquired if they should change frequencies. In the TRACON at 1059:49, the departure controller advised the pilot of N91Y to, "contact reno approach on one two six point three." The pilot acknowledged the frequency change. At 1100:15, the pilot of N91Y initially contacted the arrival radar controller in the TRACON and advised, "mooney niner one yankee is with you level at twelve five." The arrival controller then inquired if the Mooney desired flight following with Oakland ARTCC at the boundary of Reno's airspace. The pilot responded positively. After requesting information on the flight that was to be entered into the computer, at 1101:48, the arrival controller instructed the pilot, "when able squawk four five six seven." The pilot acknowledged the transponder code. The available radar data shows the airplane was 35 miles from the Reno's TRACON airspace border. At 1103:01, the departure controller transmitted to the flight crew of ASA601, ". . . contact oakland center one two eight point eight good day." The flightcrew, still on the local control frequency, did not respond. At 1103:10, the departure controller again attempted to have the flightcrew of ASA601 contact Oakland Center, without success. Concurrently, at 1103:16, the arrival controller was instructing the pilot of N91Y to change transponder codes to 4567. At 1104:11, the flightcrew of ASA601 asked the local controller if they should go to the departure frequency, to which the local controller replied, "six zero one ah contact departure." At 1104:24, the flightcrew of ASA601 transmitted, "and ah departure. . . . alaska six oh one we just had a near miss on a mooney aircraft that went by do you have him on radar." At 1104:39, the local controller replied, "mooney er ah alaska six zero one ah not at this time." The flightcrew transmitted, "we missed him as close as close as you would miss he's a white and blue airplane i'd like you to follow it up we're gonna put in a report." At 1104:50, the local controller replied, ". . . wilco." At 1106:32, the flightcrew initially contacted the departure controller at the Reno TRACON. After the departure controller acknowledged their call the flightcrew advised, "yes sir we're on frequency we never got a switch we've had a little problem with a near miss." The departure controller replied, "Alaska six zero one roger I understand I just got that from the tower I did change you to the Center about three times and didn't get a response." The flightcrew's response was unintelligible. After being instructed to climb to an altitude of flight level two three zero [FL230] at 1107:39, the flightcrew was instructed to contact Oakland Center. At 1112:41, the pilot of N91Y was also advised to contact Oakland Center. The pilot of N91Y did not comment to the arrival controller about his encounter with ASA601. The FAA Reno TRACON manager interviewed the pilot of N91Y via telephone on August 20, 1994. The pilot said that he was flying at 12,500 feet msl when an unidentified jet airplane crossed over his airplane from the left to the right and he felt the airplane's wake turbulence. The jet airplane's closest proximity was between 500 and 1,000 feet and that he pushed the airplane's nose down as an evasive action. The pilot said that the en route visibility over Reno was about 20 miles with haze. He said that during his flight, some air traffic control facilities told him that the airplane's Mode C (altitude encoding) portion of the airplane's transponder was operating intermittently. The Reno departure controller also told him that the transponder's Mode C was not operating. AIRPORT INFORMATION The Reno Tahoe Tower and TRACON are classified by the FAA as a Level III facility that operates 24-hours per day. The TRACON uses an airport surveillance radar (ASR-8) which is augmented with automated radar terminal systems (ARTS-IIA) computer processing that can generate data blocks on known aircraft for tracking them. When an airplane is so equipped, the data block will show the call sign of the aircraft, the altitude, and the ground speed. Full performance level (FPL) controllers are required to be proficient in both tower and TRACON positions of operation. National Transportation Safety Board investigators' review of the facility standard operating procedures (SOP) shows that there are seven positions of operation in the tower cab and nine positions of operation in the TRACON. These positions are usually combined or decombined, dependent upon traffic complexity and workload. Safety Board investigators interviewed the air traffic controllers involved in this incident on August 31, 1994. All of the involved controllers listened to the incident's recorded communications at various times before being interviewed (see the National Transportation Safety Board Air Traffic Group Chairman's Report for a detailed summary of the interviews). The local controller said that before the incident the cab coordinator position had been manned to help with an emergency that had occurred at the airport. At the time of the incident, the cab coordinator position was not manned. He said that it was the local controller's function to advise the departure controller of pending departures unless the aircraft is assigned a Sparks departure. Otherwise, the call sign and the Standard Instrument Departure (SID) are provided to the departure controller. The local controller said that the facility did not set a specified advance time for the local controller to advise the departure controller about a pending departure since it is done before the aircraft takes off. With respect to ASA601, the local controller said that because the cab coordinator position had been manned earlier, he could not recall if he or someone else had advised the departure controller about ASA601. The communication between the local controller and the departure controller is not recorded. The local controller told Safety Board investigators that he did not know why ASA601's flight strip was filed without the flightcrew being instructed by him to contact departure control. The departure controller/area supervisor told Safety Board investigators that besides listening to the incident's recorded communications, he reviewed some data about the incident since the occurrence. The data included reviewing the Air Traffic Control (ATC) Handbook regarding Class C separation requirements and the local Standard Operating Procedures (SOP) climb order. He also participated in a facility round table discussion of the facts and circumstances of the incident. The departure controller said that he did receive advance notification from the local controller that ASA601 would be departing. Then, he placed ASA601's flight strip directly in front of him; according to the controller, this indicates that the airplane would soon be departing. The flight strip contains the SID the flight is assigned, but there is no requirement to annotate the preprinted flight strip on the airplane; he would rely on his memory to determine if he communicated with the departing airplane. The departure controller said that he observed ASA601 auto-acquire on the radar when the flight was within 1 mile from the airport. He would expect to be in radio communication with the pilot within 2 to 3 miles from the airport, but generally before then. The departure controller did not realize that he was not in communication with ASA601 until after the incident. He said he was distracted because the outside telephone had rung at least once and that he also talked to a facility technician on the telephone immediately before the incident. The departure controller said that he would have to move from his radar position to talk on the telephone. The arrival controller said he received an automated handoff on N91Y from the departure control. The radar data block did not indicate a mode C readout, but the altitude in the data block indicated "12.5A," meaning the airplane's actual altitude was 12,500 feet msl. He said that he assigned N91Y a different transponder code, but the pilot inadvertently set the wrong code in his transponder. After a brief conversation with the pilot, the pilot set the correct transponder code. The code change was required because the pilot indicated he wanted further radar flight following from the Oakland Air Route Traffic Control Center. The arrival controller told Safety Board investigators that he did not consider N91Y's radar target as being untracked, as the airplane was in the process of changing the transponder code. He did not notice ASA601's radar data block because he was in the process of correcting N91Y's transponder code, and he was not looking for ASA601's data block. He also said that he and the departure controller were the only persons in the radar room and that the departure controller was performing other duties which included answering the telephone.
FAILURE OF THE AREA SUPERVISOR/DEPARTURE CONTROLLER (SUPVR/CTLR) TO STAY AT HIS RADAR POSITION AND ENSURE THAT REQUIRED COMMUNICATIONS WERE MAINTAINED. FACTORS RELATED TO THE INCIDENT WERE: FAILURE OF THE LOCAL TOWER CONTROLLER INSTRUCT THE FLIGHTCREW OF ASA601 (N954AS) TO CONTACT DEPARTURE CONTROL, FAILURE OF THE ARRIVAL/DEPARTURE CONTROLLERS TO ISSUE TRAFFIC ADVISORIES, SUPERVISOR/DEPARTURE CONTROLLER'S DIVERTED ATTENTION, AND INTERMITTENT OPERATION OF THE TRANSPONDER IN THE MOONEY, THUS NOT ACTIVATING THE TCAS OF ASA601.
Source: NTSB Aviation Accident Database
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