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C90 TRACON controller reported a loss of separation after clearing one aircraft to climb to an altitude that another aircraft had just left.
| Attributes | |
| ACN | 1505973 |
| Time | |
| Date | 201712 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | C90.TRACON |
| State Reference | IL |
| Aircraft 1 | |
| Make Model Name | A320 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Climb |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Hawker 900 |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Climb |
| Flight Plan | IFR |
| Person 1 | |
| Function | Approach |
| Qualification | Air Traffic Control Fully Certified |
| Experience | Air Traffic Control Time Certified In Pos 1 (yrs) 8 |
| Events | |
| Anomaly | ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Published Material / Policy |
Narrative:
Aircraft Y departed and was climbing in reference to aircraft X. Our center/TRACON LOA allows center to increase speed reference known traffic. I saw aircraft X out of 11200 ft while aircraft Y was at 8800 ft. Since 11000 ft had been vacated and center had the handoff on aircraft Y I assumed aircraft X would keep his climb rate and climbed aircraft Y to 11000 ft. When I next checked aircraft Y was leveling 11000 ft while aircraft X was showing 11600 ft with less than 3 miles separation. The way I understand the LOA is that if center has the handoff on both aircraft I can climb my aircraft to 11000 ft; since it has been vacated. However; if center speeds aircraft X up; changing the climb rate they should advise me since I am authorized to climb in reference. I believe center should either not speed up aircraft when they have the handoff on the aircraft climbing in reference or should wait to take the handoff until after they sped up aircraft X so I know that the climb rate has changed.
Original NASA ASRS Text
Title: C90 TRACON Controller reported a loss of separation after clearing one aircraft to climb to an altitude that another aircraft had just left.
Narrative: Aircraft Y departed and was climbing in reference to Aircraft X. Our Center/TRACON LOA allows Center to increase speed reference known traffic. I saw Aircraft X out of 11200 ft while Aircraft Y was at 8800 ft. Since 11000 ft had been vacated and Center had the handoff on Aircraft Y I assumed Aircraft X would keep his climb rate and climbed Aircraft Y to 11000 ft. When I next checked Aircraft Y was leveling 11000 ft while Aircraft X was showing 11600 ft with less than 3 miles separation. The way I understand the LOA is that if Center has the handoff on both aircraft I can climb my aircraft to 11000 ft; since it has been vacated. However; if Center speeds Aircraft X up; changing the climb rate they should advise me since I am authorized to climb in reference. I believe Center should either not speed up aircraft when they have the handoff on the aircraft climbing in reference or should wait to take the handoff until after they sped up Aircraft X so I know that the climb rate has changed.
Data retrieved from NASA's ASRS site 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.