N27239

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 f...