Aviation Accident Summaries

Aviation Accident Summary OPS10IA014

Worton, MD, USA

Aircraft #1

N27239

BOEING 737

Aircraft #2

N909JE

GULFSTREAM AEROSPACE G1159B

Analysis

Factual Information

On March 25, 2010, at 0904 eastern daylight time, an operational error occurred at the Washington Air Route Traffic Control Center (ZDC) when Continental Airlines flight 239 (COA239), a Boeing 737-800, en route from Miami, Florida, to Newark, New Jersey, and N909JE, a Gulfstream II en route from Palm Beach, Florida, to Teterboro, New Jersey, passed within 1.04 miles laterally and 300 feet vertically over Worton, Maryland. Both aircraft were operating on instrument flight plans in class A airspace under control of ZDC. Required minimum separation between the aircraft was 5 miles and 1000 feet. There was no damage reported to either aircraft and no injuries to passengers or crew. History of Flight COA239 and N909JE were operating in ZDC sector 10/12, which were combined positions staffed with a radar controller (R12) and a manual controller (D12). Just before the incident occurred, N909JE was at flight level (FL) 290, and COA239 was at FL360. At 0901:13, the R12 controller transmitted, “N9JE fly heading 070 vectors around restricted airspace, you can expect PEEDS in ten miles.” At 0901:23, the pilot of COA239 requested descent, and the controller issued clearance to FL270. At 0902:34, the R12 controller instructed N909JE to fly heading 100, and the pilot acknowledged. At 0903:07, the R12 controller transmitted, “Continental 239, contact Washington Center [on frequency] 125.45,” (ZDC sector 19) and the pilot acknowledged. At 0903:14, the controller cleared N909JE to descend to FL240. At 0903:31, the R12 controller contacted the R19 controller, stating, “…I just started 9JE down to [FL] 240 ... thought he was going to go more behind the Continental.” The R19 controller asked, “Are they coming together there?”, and the R12 controller responded, “uh, yeah.” The R19 controller then asked, “…Are you talking to JE?” The R12 controller again responded, “Yes,” and the R19 controller asked, “Do you want me to stop Continental?” The R12 controller answered, “Yes.” The R19 controller responded, “All right – hold on” and the call terminated. The R12 controller then transmitted, “…9JE increase your rate of descent traffic one o’clock five miles a 737 descending FL270.” The pilot of N909JE responded, “…we got the traffic in sight.” At 0904:24, the pilot of N909JE stated, “…JE’s gonna divert to the left… we got visual on the traffic.” The controller acknowledged both reports. At 0904:46, the R19 controller contacted the R12 controller on the interphone, stating, “…mine’s below yours just so you know.” At 0905:08, the R12 controller transmitted, “N9JE maintain FL270 – traffic’s now below you,” and the pilot acknowledged. At that point, the conflict was resolved and N909JE was cleared to proceed direct to DuPont. The control room operations manager was alerted to the loss of separation between N909JE and COA239 by the Operational Error Detection Program. The operations manager telephoned the supervisor responsible for sector 12, who spoke with the controllers at the sector, confirmed that an incident had occurred, and began the investigation. Personnel Interviews R10/12 Controller The R10/12 controller entered on duty with the FAA on May 11, 2007, and began working at ZDC on August 20, 2007. She was in training, certified on seven D-positions and three radar positions. She was certified on sectors 10 and 12 in September 2009, and was also fully qualified on sector 16, with further training to come on sectors 20, 21, 11, and 14. She was a 2005 graduate of the air traffic control program at Beaver College, where she obtained a control tower operator certificate. She also held a commercial pilot certificate with an airplane-instrument rating, although she was not current. Her normal days off were Thursday and Friday, but she was on leave for most of the week of the incident, and the day it occurred (March 25, 2010) was the end of 7 days off. She reported no limitations on her medical certificate. The R10/12 controller stated that she was comfortable with the way her training had been proceeding. She reported that developmental controllers (controllers in training) are allocated 120 to 140 hours of training time for each radar position. At the time of the incident she was training on sectors R20 and R21. Although sector 19 (the other position involved in the incident) was not part of her area of specialization, she was familiar with the operations there. She had seen the replay of the incident since it occurred. Asked to explain the operations and airspace involved in the incident, she noted that sectors 10 and 12 were combined, and she owned FL240 and above except for a small area at the southwest corner of the sector. She had been vectoring N909JE for in-trail spacing behind another aircraft en route to TEB, but then needed to turn N909JE east to avoid the Aberdeen restricted area. She told the pilot to fly heading 070, but then decided that she needed to go further because of strong winds from the west and instructed the pilot to fly heading 100. Once the vector was completed, she intended to send N909JE direct to PEEDS. She expected that the 100 heading would put N909JE behind COA239, which was inbound to EWR on a northwesterly track to the east of N909JE. The aircraft didn’t turn as quickly as she expected, and the easterly heading caused a groundspeed increase because of the westerly winds. The R10/12 controller continued to believe that the heading assigned to N909JE would result in the aircraft going behind COA239 and maintaining lateral separation. After the pilot requested descent, she cleared COA239 to descend to FL270. Shortly afterward she instructed COA239 to contact the controller at sector 19. She then cleared N909JE to descend to FL240. Almost immediately, she realized that N909JE and COA239 were converging and would not be separated. She called the sector 19 controller about the problem. Asked what her plan was, she stated that she intended to tell R19 to stop COA239’s descent. When questioned, she was unable to explain why she had not issued any such instructions on first contact with the other controller. She could not explain why she waited so long to resolve both the need for N909JE to miss the Aberdeen airspace and the separation issue with COA239. She stated that she was definitely aware of the conflict, but that she was trying to remain calm and not to panic. She was also unable to explain the delay between the R19 controller’s call reporting that COA239 was now below N909JE, and her amendment of N909JE’s existing FL240 descent clearance to maintain a higher altitude that would ensure separation from COA239, except to say that she was uncertain of COA239’s altitude. She stated that she had a J-ring (5nm circle to aid in visualizing separation) on one of the aircraft, but could not recall which one. After the incident occurred, the supervisor came to sector 12 to ask what had happened and if it was a "real conflict." The R10/12 controller told him what had occurred and that there had been a loss of separation. She had discussed the incident with several people since it occurred, including the supervisor and other controllers, but she stated there had been no official review of what took place. She was assigned skill enhancement training, including simulation problems, computer-based instruction lessons, and other materials. The simulation sessions were to emphasize positive control and ensuring separation. She stated that there was emphasis on resolving bad situations as part of her previous training, but she was unable to recall any specific details. Asked what she would do differently if again presented with the same scenario, the R10/12 controller stated that she would retain communications with COA239 until the conflict was resolved, use vertical separation more effectively, and be more aggressive about vectoring to obtain needed spacing. Asked to describe the terms used in FAA Order 7110.65, "Air Traffic Control," to instruct a pilot to act without delay, she quickly answered “immediately” and “expedite.” However, she did not believe that she needed to issue such instructions to N909JE to resolve the situation with COA239. She underestimated the effect of the strong westerly winds. She explained that the effect of the wind was to widen the ground track of turning aircraft, and increase the groundspeed of eastbound flights. She did not consider turning COA239 to the west to achieve separation because she would possibly had a conflict with the Aberdeen airspace. The R10/12 controller reported that she had not had any other losses of separation since she began training. Supervisors monitor her regularly as part of their general supervision activities, but she had not had any formal performance reviews such as over-the-shoulder checks or tape talks on those radar sectors where she was certified. The controller on the manual position assisting her at the time of the incident was also a developmental and was not radar qualified. She noted that manual controllers are assigned as traffic requires, on average being assigned with her about half the time. While training on other positions, she worked sector 10/12 about once or twice a week, although she had no estimate of average hours on the position per month. Because of her time off, she had not worked the position for about a week. R18/19 Controller The controller handling COA239 at the time of the conflict was working sectors 18 and 19 combined. These sectors had various vertical limits, with shelves to accommodate aircraft executing descents into the New York area. The sector included both low altitude and high altitude airspace, with a base altitude of 8000 feet at the low point. When COA239 was handed off to sector 19, the aircraft was about 12 miles south of the southern border of the sector. The R18/19 controller stated that at that time he was just coming out of holding for the LaGuardia Airport, which required him to focus most of his attention on the north end of the sector, about 70 miles north of COA239. There were no other unusual circumstances affecting the sector. When the R18/19 controller accepted the handoff on COA239, he was not aware of N909JE as the aircraft had not been handed off yet. When COA239 made initial contact, he cleared the pilot to descend to FL240. He then accepted the handoff on N909JE, and immediately received a phone call from sector 12 about the conflict. The conflict alert was not yet going off, but it activated shortly afterward. The sector 12 controller stated, “I’m starting the aircraft down right now.” The R18/19 controller then realized that, "...it wasn't going to work," asked the R12 controller if the aircraft were coming together and then asked her what she wanted to do. He told COA239 to maintain present altitude. COA239 responded that they had a Resolution Advisory (RA) and would be following it. COA239 might have actually turned slightly 10-15 degrees to the right. The R18/19 controller then called sector 12 back and advised the radar controller that the Continental flight was now below her traffic (N909JE). After concluding the phone call, he did not see the data block for N909JE update to show a new altitude, so he shouted over to sector 12 to stop N909JE at flight level 270. The new altitude then showed up in the data block. The R18/19 controller said that once he realized there was a conflict, he was preparing to issue some control instructions. COA239 then reported receiving the resolution advisory. At that point, he decided to just let the pilot follow the advisory. It is his understanding that Traffic Alert and Collision Avoidance System (TCAS) equipment doesn’t give turn instructions but is more oriented toward climb or descent, and he did not want to issue an instruction that could interfere with TCAS. Sector 12 Manual Controller (D10/12) The controller working the manual position at sector 10/12 entered on duty with the FAA in November 2008, and came to ZDC in January 2009. He was certified the manual positions at sectors 11, 14, 20, 21, 16, 10, and 12. He planned to begin radar training on April 5. The D10/12 controller assessed the traffic at the time as light to moderate, with no unusual issues with equipment, weather, or other circumstances. He first became aware that something was wrong when the radar controller instructed COA239 to contact sector 19 and then immediately called the sector 19 controller with additional coordination. He noticed the conflict, but he did not discuss it with the radar controller because she was clearly aware of it and working on it with sector 19. The D10/12 controller stated that as a manual controller, he was expected to check routes, make point outs, and assist the radar controller as necessary. He had no involvement in the incident once it occurred. The supervisor had been monitoring the position, but left just before the incident. After the incident, the supervisor came back to the sector to see what happened. He asked if the conflict was real or a false alarm. The sector 12 controllers advised him that it was a real conflict. The D10/12 controller was aware of the procedure for contacting Aberdeen to coordinate airspace issues, but he had never had to use it. He said that he was comfortable working with older and more experienced controllers, and had no concerns about speaking up when he saw something wrong or observed a conflict. He did not believe that the User Request Evaluation Tool indicated any sort of a conflict during this incident. Supervisor The supervisor involved in this incident entered on duty with the FAA on May 9, 1989, completed training on December 10, 1992, and became a supervisor in January of 2003. He maintained currency on the radar positions at sectors 10 and 12, and worked the positions approximately 15 to 20 hours a month, with more time on position in the summer because of staffing. He was the R10/12 controller's supervisor of record, and worked with her approximately 4 to 5 days a week. He was responsible for investigating the operational error, and had reviewed replays and the audio recordings of the incident. At the time of the interview, he had not seen the SATORI replay of the incident. The supervisor participated in the development of the skill enhancement training the facility had assigned to the R10/12 controller as a result of the operational error. The supervisor stated that he had two developmental controllers on his crew, and it is his practice to monitor them on a regular basis as part of his supervisory duties. One of them was working as the manual controller at sector 12 assisting the other developmental, who was the R10/12 controller. The supervisor first became aware of the incident at sector 12 when he received a telephone call from the operations manager desk advising him that the Operational Error Detection Program had detected a possible loss of separation at the sector. He walked to sector 12 and asked the R10/12 controller what had happened. She described the incident. The supervisor said that he had been monitoring sector 12 for about 15 minutes, but had to leave the sector for a few minutes to process an airspace status change at the supervisor desk. The incident occurred while he was away from the sector. He assessed the workload of the sector as light throughout the entire period. Asked about his assessment of the R10/12 controller's training progress and performance, the supervisor stated that her progress was normal in comparison with other developmental controllers. Her training write-ups included comments about maintaining positive control, making handoffs in a timely manner, and using good control judgment. The supervisor was responsible for certifying the R10/12 controller on sector 12, and stated that at the time he performed the certification, the session went 2 to 3 hours and was conducted with the concurrence of the training team that she was ready to be certified. The supervisor stated that from observation, the R10/12 controller had regressed somewhat du

Probable Cause and Findings

The R10/12 controller issued an improper vector and descent clearance to the GII that put the airplane on a coverging flight path with the B737. Contributing to the incident was the failure of the FAA's training program to correct ongoing controller performance deficiencies before certifying the D10/12 controller to work without immediate supervision.

Source: NTSB Aviation Accident Database

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