Narrative:

This is actually 2 events. First; on the departure off ZZZ1 there were 3 aircraft in trail climbing out: air carrier west; then air carrier X (aircraft 1); then air carrier Y (aircraft 2). ZZZ1 approach issued air carrier Y 250 KTS to keep in trail spacing behind air carrier X. Air carrier Y overtook air carrier X despite the speed restriction of 250 KTS. I was training an r-side developmental at the time. He issued 270 KTS to air carrier X and then I keyed up and issued air carrier Y 30 degrees left. We also stopped the air carrier Y at FL180; and requested a report out of FL190 on air carrier X. It seems that either air carrier Y was going faster than 250 KTS or air carrier X was climbing at a reduced rate of 220 KTS or maybe even less. We did not ask the pilot of air carrier X his climbing speed. Separation was about 5 miles or 1;000 ft; but it was close to being a loss of separation. Meanwhile; another sector called to point out an emergency aircraft that was descending at a rapid rate. They said he was descending to 16;000 ft. I informed him of traffic; air carrier Y at FL180. The emergency aircraft was descending so quickly that the altitude was XXX'ed out. He said that a different sector was actually talking to him. Called traffic to the air carrier Y; informing him that the emergency would be descending through his altitude. The other sector called back to say that the emergency was through 13;000 ft. Air carrier Y never reported the emergency aircraft in sight. Be aware of reduced rates of speed during the climbing portion of the flight.

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Original NASA ASRS Text

Title: Enroute Controller providing OJT described a near loss of separation event when two in trail departure aircraft varied from expected speeds. The situation was complicated by an emergency aircraft descending at a very rapid rate.

Narrative: This is actually 2 events. First; on the departure off ZZZ1 there were 3 aircraft in trail climbing out: Air Carrier W; then Air Carrier X (aircraft 1); then Air Carrier Y (aircraft 2). ZZZ1 Approach issued Air Carrier Y 250 KTS to keep in trail spacing behind Air Carrier X. Air Carrier Y overtook Air Carrier X despite the speed restriction of 250 KTS. I was training an R-Side Developmental at the time. He issued 270 KTS to Air Carrier X and then I keyed up and issued Air Carrier Y 30 degrees left. We also stopped the Air Carrier Y at FL180; and requested a report out of FL190 on Air Carrier X. It seems that either Air Carrier Y was going faster than 250 KTS or Air Carrier X was climbing at a reduced rate of 220 KTS or maybe even less. We did not ask the pilot of Air Carrier X his climbing speed. Separation was about 5 miles or 1;000 FT; but it was close to being a loss of separation. Meanwhile; another sector called to point out an Emergency aircraft that was descending at a rapid rate. They said he was descending to 16;000 FT. I informed him of traffic; Air Carrier Y at FL180. The emergency aircraft was descending so quickly that the altitude was XXX'ed out. He said that a different Sector was actually talking to him. Called traffic to the Air Carrier Y; informing him that the emergency would be descending through his altitude. The other sector called back to say that the emergency was through 13;000 FT. Air Carrier Y never reported the Emergency aircraft in sight. Be aware of reduced rates of speed during the climbing portion of the flight.

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.