Narrative:

Routine traffic; it started with the departure of a falcon 2000; departed on [a SID] departure. For noise abatement the aircraft start their turn on the departure at 1.8 DME and 2;000 ft. The falcon started his turn but turned wider than normal. Tower has automatic releases and releases aircraft 5 miles in trail per the LOA. When the second aircraft departed; a citation X; there was 4.51 NM between the two aircraft. The citation started his turn at 1.8 DME but turned tight and it was observed that there was going to be an issue between the 2 aircraft. The second aircraft was potentially turning inside of the first aircraft. During this time; training was going on in the sector. I immediately noticed the issue and began telling my trainee about the issue and that something needed to be done immediately. His first thought was to climb the first aircraft but only climbed him 1;000 ft. He gave traffic trying to get the traffic insight but the second aircraft was unable to initially get the traffic insight. The first aircraft started climbing as the second aircraft was also in the turn for [another SID] departure. In the turn it appeared that we did have the 3 miles required and seconds later we had the 1;000 ft requirement. At the same time; I also gave the second aircraft a heading to the right of 180 degrees to ensure separation. When the heading was issued the second aircraft reported that he had the traffic insight. I instructed the aircraft to maintain visual separation from that traffic and turn back to a 120 degree heading. While both aircraft are in the turn and flying different patterns it is hard to determine if separation is lost. It appeared to me that we did have three miles and 1;000 ft prior to the visual separation; however; it was reported that separation had diminished in the turn at one point to 1.84 NM and 400 ft as the aircraft was rapidly climbing. Neither aircraft reported a TCAS event as they were on different departure procedures and were continuing away from each other. There are many different methods that can be used to alleviate this scenario in the future. One of the issues was that training was in progress and although the trainee was new to this sector he/she was not new to the area and I afforded too much latitude in his/her decision making. I should have taken control immediately and made the scenario work rather than let it develop as it did. This is a common problem with successive departures off [this airport]. All aircraft fly the departures a little differently which can cause problems when you are getting departures with minimal separation. One way to solve the problem is control the turns for the departures to ensure no misconceptions and all aircraft are under your control. Also; what should have happened immediately is that a traffic alert should have been given to ensure each aircraft involved start to listen up more effectively. During the event when the first aircraft was climbed he questioned the climb before starting the climb that costs valuable time. Another solution to fix the problem would have been to cap the altitude of the second aircraft to 4;000 while the second aircraft was at 5;000 just ensure that the second aircraft stayed away from the 4;100 MVA. This sector requires positive control at all times. It is situated right under [a class B airport's] finals and just south of [a class C airport's] finals; there is no room for error and precision is a must. Attention to detail and ensuring all aircraft are complying will all procedures at all times. Always use caution with business jets; they don't fly these abnormal departure procedures as often as the airliners. I know the hazards of the position well and was just discussing with my trainee what to look for and how to fix it. The problem was I didn't take control soon enough and should have ensured separation first and discussed how he would have handled it later. This is not an abnormal situation. In sector X it is notabout if this will happen again but when will this happen again and the answer is sooner rather than later. We have to constantly have a plan B for when it does. I know this and should have ensured separation before it ever got this far. I have learned a valuable lesson when training.

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Original NASA ASRS Text

Title: TRACON Controller providing OJT described a loss of separation event when a second departure turned inside the previous departure causing the conflict; the reporter acknowledging a failure to intercede in time.

Narrative: Routine traffic; it started with the departure of a Falcon 2000; departed on [a SID] departure. For noise abatement the aircraft start their turn on the departure at 1.8 DME and 2;000 FT. The Falcon started his turn but turned wider than normal. Tower has automatic releases and releases aircraft 5 miles in trail per the LOA. When the second aircraft departed; a Citation X; there was 4.51 NM between the two aircraft. The Citation started his turn at 1.8 DME but turned tight and it was observed that there was going to be an issue between the 2 aircraft. The second aircraft was potentially turning inside of the first aircraft. During this time; training was going on in the sector. I immediately noticed the issue and began telling my Trainee about the issue and that something needed to be done immediately. His first thought was to climb the first aircraft but only climbed him 1;000 FT. He gave traffic trying to get the traffic insight but the second aircraft was unable to initially get the traffic insight. The first aircraft started climbing as the second aircraft was also in the turn for [another SID] departure. In the turn it appeared that we did have the 3 miles required and seconds later we had the 1;000 FT requirement. At the same time; I also gave the second aircraft a heading to the right of 180 degrees to ensure separation. When the heading was issued the second aircraft reported that he had the traffic insight. I instructed the aircraft to maintain visual separation from that traffic and turn back to a 120 degree heading. While both aircraft are in the turn and flying different patterns it is hard to determine if separation is lost. It appeared to me that we did have three miles and 1;000 FT prior to the visual separation; however; it was reported that separation had diminished in the turn at one point to 1.84 NM and 400 FT as the aircraft was rapidly climbing. Neither aircraft reported a TCAS event as they were on different departure procedures and were continuing away from each other. There are many different methods that can be used to alleviate this scenario in the future. One of the issues was that training was in progress and although the Trainee was new to this sector he/she was not new to the area and I afforded too much latitude in his/her decision making. I should have taken control immediately and made the scenario work rather than let it develop as it did. This is a common problem with successive departures off [this airport]. All aircraft fly the departures a little differently which can cause problems when you are getting departures with minimal separation. One way to solve the problem is control the turns for the departures to ensure no misconceptions and all aircraft are under your control. Also; what should have happened immediately is that a traffic alert should have been given to ensure each aircraft involved start to listen up more effectively. During the event when the first aircraft was climbed he questioned the climb before starting the climb that costs valuable time. Another solution to fix the problem would have been to cap the altitude of the second aircraft to 4;000 while the second aircraft was at 5;000 just ensure that the second aircraft stayed away from the 4;100 MVA. This sector requires positive control at all times. It is situated right under [a Class B airport's] finals and just south of [a Class C airport's] finals; there is no room for error and precision is a must. Attention to detail and ensuring all aircraft are complying will all procedures at all times. Always use caution with business jets; they don't fly these abnormal departure procedures as often as the airliners. I know the hazards of the position well and was just discussing with my Trainee what to look for and how to fix it. The problem was I didn't take control soon enough and should have ensured separation first and discussed how he would have handled it later. This is not an abnormal situation. In Sector X it is notabout if this will happen again but when will this happen again and the answer is sooner rather than later. We have to constantly have a plan B for when it does. I know this and should have ensured separation before it ever got this far. I have learned a valuable lesson when training.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.