ZMP instructor and developmental describe a situation where the developmental used vacated altitude ...

Attributes
ACN	1207635
Time
Date	201410
Local Time Of Day	1201-1800
Place
Locale Reference	ZMP.ARTCC
State Reference	MN
Environment
Light	Daylight
Aircraft 1
Make Model Name	Medium Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Aircraft 2
Make Model Name	Medium Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Person 1
Function	Enroute Instructor
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 22
Person 2
Function	Enroute Trainee
Qualification	Air Traffic Control Developmental
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

Narrative:

I was the trainer at sector 38. Tmu restriction of 15 mit to den. Departure push out of dsm and we were handed maybe 5 aircraft needing to be spaced. Aircraft X checked on and was given climb and maintain I believe FL280. Just behind aircraft X was aircraft Y who was initially given a altitude below aircraft X. My trainee was starting spacing and assigning speeds as well as altitudes and requested aircraft Y to expedite his climb through FL240 for traffic inbound (a air carrier who was turned out). When my trainee observed aircraft X out of FL260; he assigned aircraft Y FL260 and gave him normal rate of climb. I told my developmental I did not like that plan and to change it so he revised the clearance to FL250 again but the pilot read back; 'ok; we will maintain 2-5-0 on the speed.' neither of us heard the speed part because of the activity and trainer/trainee communication going on. As I observed the aircraft X go through the altitude I attempted to correct the mistake but was too late. Not sure if separation was lost but the plan did not work either way. I don't use it and neither should anyone. Just because a similar aircraft is out of an altitude; does not mean or should it mean that you can assign that altitude to another aircraft. There are just too many factors that can make an aircraft climb at different rates.

Original NASA ASRS Text

Title: ZMP instructor and Developmental describe a situation where the Developmental used vacated altitude rule and the second aircraft climbed faster than the first aircraft leading to a loss of separation.

Narrative: I was the trainer at sector 38. TMU restriction of 15 MIT to DEN. Departure push out of DSM and we were handed maybe 5 aircraft needing to be spaced. Aircraft X checked on and was given climb and maintain I believe FL280. Just behind Aircraft X was Aircraft Y who was initially given a altitude below Aircraft X. My Trainee was starting spacing and assigning speeds as well as altitudes and requested Aircraft Y to expedite his climb through FL240 for traffic inbound (a air carrier who was turned out). When my trainee observed Aircraft X out of FL260; he assigned Aircraft Y FL260 and gave him normal rate of climb. I told my developmental I did not like that plan and to change it so he revised the clearance to FL250 again but the pilot read back; 'Ok; we will maintain 2-5-0 on the speed.' Neither of us heard the speed part because of the activity and trainer/trainee communication going on. As I observed the Aircraft X go through the altitude I attempted to correct the mistake but was too late. Not sure if separation was lost but the plan did not work either way. I don't use it and neither should anyone. Just because a similar aircraft is out of an altitude; does not mean or should it mean that you can assign that altitude to another aircraft. There are just too many factors that can make an aircraft climb at different rates.

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.

ZMP instructor and developmental describe a situation where the developmental used vacated altitude rule and the second aircraft climbed faster than the first aircraft leading to a loss of separation.