Date: 201701
Local time of day: 0601-1200
Location: ZDV.ARTCC, CO
Flight conditions: VMC
Light: Daylight
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZDV
ATC / advisory: Center ZDV
Second aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Reporter organization: Government
Reporter function: Trainee; Enroute
Reporter qualification: Air Traffic Control Developmental
Human factors: Situational Awareness; Distraction
Second reporter function: First Officer; Pilot Not Flying
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Undershoot; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Aircraft; Procedure; Weather; Human Factors
Primary problem: Ambiguous

Narrative: I was the controller training on the sector. The traffic volume and complexity began to pick up due to turbulent ride conditions and an aircraft that I was in communication with making accidental transmissions over guard which indicated a medical problem on board. Aircraft X came onto the frequency after taking the handoff from Sector 07. Upon check-on Aircraft X asked about ride conditions at 37000 feet. I responded that 37000 feet was reporting occasional light chop and Aircraft X then requested a climb to that altitude. I observed traffic in front of Aircraft X opposite direction at 36000 feet and gave Aircraft X a clearance to climb to reach 37000 feet in 2 minutes or less. The pilot read back the clearance correctly and at this point had 40 miles of separation with 3 minutes before 5 miles of separation would be lost. At this time I began trying to gather information on what was potentially a medical emergency being broadcast over guard by another aircraft whom I also had on my frequency. Scanning back to Aircraft X the climb rate indicated he would easily make his restriction but after a few more transmissions I observed that Aircraft X had leveled out at 36600 feet. After observing this; I issued Aircraft Y a descent to 35000 feet to achieve separation but the pilot than hesitated saying; 'Descending in response to a TCAS.' Aircraft Y at this time had still not actually began a descent according to our RADAR display and my trainer than keyed up to issue a descent clearance once more. The aircraft broke required separation with 4.7 miles and 800 feet. Aircraft X reached 37000 feet 3:20 minutes after reading back the restriction. In this event; I would like that the pilot be instructed that if he cannot meet a climb restriction to advise as soon as possible so an alternative action can be taken immediately.


Second narrative: In cruise at 35000 feet with Center we requested a climb to 37000 feet. Center issued the following clearance. 'Climb and maintain flight level 370; be level in 2 minutes or less'. Initiated climb and started timer. At 2 minutes we had attained 36;500 feet. I informed ATC that we would not be able to make it to 37000 feet within the 2 minutes. ATC issued a clearance to a converging aircraft to descend to 35000 feet. At 36600 feet we received a TCAS RA 'monitor vertical speed'. A repeat clearance to Aircraft Y was made by ATC to descend to 35000 feet. I had Aircraft Y in sight for the entire event and verbalized this to ATC. We were able to maintain visual separation and vertical separation was never less than 500 feet.ATC issued timed climb without asking if we could accomplish it. We didn't realize that we wouldn't be able to comply until 36600 feet.


Synopsis: ZDV Controller and the flight crew involved reported they did not comply with a clearance to be level at an altitude in two minutes or less. A loss of separation with opposite direction traffic resulted.