Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 13.0
Communication Breakdown; Workload; Situational Awareness
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Returned To Clearance
Airspace Structure; Human Factors; Procedure
I was working the morning departure push of aircraft from. At the time of the event I was working between 4 to 6 aircraft. All were on RNAV SIDS.  Aircraft X; was climbed to 17;000 feet via the SID. Aircraft Y was climbed to 17;000 feet upon initial contact after departing. Aircraft Y was on a SID.The paths of the SIDs cross. When I climbed Aircraft Y to 17;000 feet Aircraft X was a few miles west of its departure airport out of an altitude of somewhere between 5000 feet and 10;000 feet. I was reasonably assured; based on the good climb rate of this morning's group of aircraft; that Aircraft Y would not be in conflict with the other aircraft climbing. I was led to this assumption because aircraft previous to Aircraft X were switched to my frequency well before my airspace boundary and in more than ample time for me to climb the aircraft to 23;000 feet and easily top the aircraft departing DCA which were climbing only to 17;000 feet.  All of my assumptions and decision making based on how the aircraft were performing was all for naught.  Aircraft X was never switched to my frequency by the adjacent sector controller and flew for approximately 6 miles into my airspace at 17;000 feet converging with Aircraft Y which was climbing out of 16;000 feet for 17;000 feet when I recognized the problem.  I immediately issued a vector to Aircraft X that would have caused it to pass behind Aircraft Y.  No answer.  I called Aircraft X again; no answer.  I instructed Aircraft Y to descend immediately to 14;000 feet and issued the traffic.  No answer.  Again I instructed Aircraft Y; now level at 17;000 feet; to descend immediately to 14;000.  (Why 14;000 feet?  It was something to aim for lower the Aircraft X at 17;000 feet.).  A pause; then Aircraft Y answered stating they were descending.  2 seconds too late.  I then instructed Aircraft Y to turn left to a heading; maybe 280 degrees; I don't remember exactly. Any heading to the left of the course Aircraft Y was on was one that I had hoped would avoid what was looking like an imminent collision; even though I was told the closest proximity was 1.9 miles and 2.1 miles.After Aircraft Y responded that they were descending to 14;000 feet I called the adjacent sector controller and told her 'Aircraft X was not on my frequency.'  A couple seconds later Aircraft X called me level at 17;000 feet and I immediately issued a climb to 23;000 feet.  Again; 2 seconds too late.I did not issue traffic alerts to either aircraft because in my opinion that was wasting precious time to correct the error and keep a bad situation from ending much worse. There has been a great initiative to introduce RNAV SIDs and STARs into the National Airspace System (NAS).  Virtually every air carrier that operates within the Potomac TRACON airspace is on a charted RNAV SID or STAR.  The result is a known path and altitude crossing restriction for each aircraft with minimal input from the air traffic controller.  Sounds like a good idea.  And it is except that the air traffic controller now spends more time monitoring an aircraft's compliance with the SID/STAR rather than directly controlling it with vectors and altitude assignments.  This; I believe; leads to a sense of complacency or expectation bias that was not as prevalent in air traffic control before the introduction of RNAV SIDS and STARS as they are used now.  This does not take away from the fact that I erred in not ensuring separation.  This event makes me more aware than ever that with less interaction between air traffic controller and pilot it now requires more vigilance on ensuring separation.
A controller took handoffs on two departures off different airports on converging routes. Although both aircraft were climbing to 17;000 feet; the controller was initially only in communication with one of the aircraft. He could not make contact with the aircraft he intended to keep climbing and waited too long to issue other aircraft instructions to ensure separation.