Narrative:

Traffic was heavy but not unusual. We fly this leg often and felt it was normal. WX was very good. Center controller seemed to be having trouble keeping up to the required pace. Descent was being issued piece-meal as we approached 12000 ft, we were cleared to 10000 ft. At 10500 ft, descending approximately 1000 FPM, we were instructed to expedite level at 10000 ft. Before we could reply we were 10400 ft and would normally be adding power to level off. In an effort to comply the leveling maneuver was delayed just a moment. This type of ATC instruction is not appropriate unless there is an emergency and traffic is issued. Even then, it could easily contribute to an altitude deviation, ie, overshoot of assigned altitude. Moments later, a discussion took place between the center and a jet behind us. The even ended with the controller instructing the jet to expedite back up to 110000 ft. We looked at our TCASII and observed traffic on the 2 mi range mark, 500 ft above us. Simultaneously then controller instructed us to expedite down to 9000 ft. We went to idle power immediately and did so. We observed on TCASII that the traffic behind us did climb and when the dust settled, 2000 ft of vertical separation was achieved, moments later we sighted the DC9 overhead. We had been subject to speed control for about 100 mi, which we prefer over holding, but shortly after the switch to approach control we were instructed to reduce to a speed that was above our current assigned speed. This indicates the center controller had also failed to properly coordination pertinent flight information to the receiving controller.

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Original NASA ASRS Text

Title: RPTS FROM BOTH FLCS INDICATE THAT THE APCH CTLR WAS BEHIND IN ALT CLRNCS AND HAD TO EXPEDITE BOTH ACFT TO MAINTAIN SEPARATION.

Narrative: TFC WAS HVY BUT NOT UNUSUAL. WE FLY THIS LEG OFTEN AND FELT IT WAS NORMAL. WX WAS VERY GOOD. CTR CTLR SEEMED TO BE HAVING TROUBLE KEEPING UP TO THE REQUIRED PACE. DSCNT WAS BEING ISSUED PIECE-MEAL AS WE APCHED 12000 FT, WE WERE CLRED TO 10000 FT. AT 10500 FT, DSNDING APPROX 1000 FPM, WE WERE INSTRUCTED TO EXPEDITE LEVEL AT 10000 FT. BEFORE WE COULD REPLY WE WERE 10400 FT AND WOULD NORMALLY BE ADDING PWR TO LEVEL OFF. IN AN EFFORT TO COMPLY THE LEVELING MANEUVER WAS DELAYED JUST A MOMENT. THIS TYPE OF ATC INSTRUCTION IS NOT APPROPRIATE UNLESS THERE IS AN EMER AND TFC IS ISSUED. EVEN THEN, IT COULD EASILY CONTRIBUTE TO AN ALTDEV, IE, OVERSHOOT OF ASSIGNED ALT. MOMENTS LATER, A DISCUSSION TOOK PLACE BTWN THE CTR AND A JET BEHIND US. THE EVEN ENDED WITH THE CTLR INSTRUCTING THE JET TO EXPEDITE BACK UP TO 110000 FT. WE LOOKED AT OUR TCASII AND OBSERVED TFC ON THE 2 MI RANGE MARK, 500 FT ABOVE US. SIMULTANEOUSLY THEN CTLR INSTRUCTED US TO EXPEDITE DOWN TO 9000 FT. WE WENT TO IDLE PWR IMMEDIATELY AND DID SO. WE OBSERVED ON TCASII THAT THE TFC BEHIND US DID CLB AND WHEN THE DUST SETTLED, 2000 FT OF VERT SEPARATION WAS ACHIEVED, MOMENTS LATER WE SIGHTED THE DC9 OVERHEAD. WE HAD BEEN SUBJECT TO SPD CTL FOR ABOUT 100 MI, WHICH WE PREFER OVER HOLDING, BUT SHORTLY AFTER THE SWITCH TO APCH CTL WE WERE INSTRUCTED TO REDUCE TO A SPD THAT WAS ABOVE OUR CURRENT ASSIGNED SPD. THIS INDICATES THE CTR CTLR HAD ALSO FAILED TO PROPERLY COORD PERTINENT FLT INFO TO THE RECEIVING CTLR.

Data retrieved from NASA's ASRS site as of July 2007 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.