Summary of the Incident
On March 25, 2010, at 0904 eastern daylight time, an operational error occurred at the Washington Air Route Traffic Control Center (ZDC) involving two aircraft. 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 under instrument flight rules in Class A airspace under ZDC control. The required minimum separation was 5 miles laterally and 1,000 feet vertically. No damage was reported to either aircraft, and no injuries occurred to passengers or crew.
Sequence of Events
N909JE was initially at flight level (FL) 290, and COA239 at FL360. The radar controller (R12) instructed N909JE to fly heading 070 to avoid restricted airspace, later amending to heading 100. COA239 requested descent and was cleared to FL270, then handed off to sector 19. The R12 controller then cleared N909JE to descend to FL240. Shortly thereafter, the controller realized the aircraft were converging and contacted the R19 controller, asking to stop COA239's descent. The R19 controller asked if the aircraft were coming together and was told yes. The R12 controller then instructed N909JE to increase rate of descent and advised traffic. The pilot of N909JE reported visual contact. The R19 controller later informed the R12 controller that COA239 was below N909JE, and the R12 controller amended N909JE's clearance to maintain FL270. The conflict was resolved.
Personnel Interviews
The R12 controller (developmental) had been certified on sectors 10 and 12 in September 2009. She reported that she intended to vector N909JE behind COA239 but underestimated the effects of strong westerly winds on the aircraft's ground track and speed. She became aware of the conflict but delayed taking corrective action. She stated she was trying to remain calm and not panic. She later participated in skill enhancement training.
The R18/19 controller, who handled COA239 after handoff, was not initially aware of N909JE. He cleared COA239 to descend to FL240 before learning of the conflict. COA239 subsequently reported a Traffic Alert and Collision Avoidance System (TCAS) Resolution Advisory, and the controller allowed the pilot to follow it.
The manual controller (D10/12) noticed the conflict but did not intervene as the radar controller appeared to be addressing it.
The supervisor was away from the sector when the incident occurred. He assessed the R12 controller's training progress as normal but noted issues with control judgment and lack of urgency. He attributed some regression to her being in training.
Radar Data
Radar data from the ASR-9 sensor at Baltimore, Maryland, approximately 27 miles from the crossing point, was obtained and placed in the docket.