Narrative:

Military X (an F-16) checked on my frequency climbing to FL200 out of about FL186. I descended him to 8000 ft to get him started down to go under military airspace active 8000 to FL280. At the time, I had crossing traffic at 7000 ft, so I couldn't start him down all the way. Military X rogered my clearance and said 'descending to 8000.' I gave him an altimeter and said, 'I'm going to have to have you down to 7000 by about ste.' I waited a few seconds and military X never gave any reply. I then went to the crossing traffic at 7000 ft and issued them lower altitudes. My d-side was busy coordinating with other facilities, so I had to do some coordination with a VFR tower in my sector besides answering numerous calls from other aircraft. Right around ste, military X checked level at 7000 ft. The conflicting aircraft, a single engine cessna had just checked out of 7000 ft. There was only a couple hundred feet separation and maybe 2 mi. I told the military X I had only issued him 8000 ft and climbed him back up to 800 ft and gave him a 90 degree turn. After listening to the tapes, I realize the military X had tried to call me, but due to frequency congestion and my being on the landline, I never heard him. I realize my poor phraseology confused military X but I also think pilots need to be reminded that unless the terms 'descend and maintain, climb and maintain or cross at and maintain' are used there is no new altitude clearance.

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Original NASA ASRS Text

Title: PLTDEV.

Narrative: MIL X (AN F-16) CHKED ON MY FREQ CLBING TO FL200 OUT OF ABOUT FL186. I DSNDED HIM TO 8000 FT TO GET HIM STARTED DOWN TO GO UNDER MIL AIRSPACE ACTIVE 8000 TO FL280. AT THE TIME, I HAD XING TFC AT 7000 FT, SO I COULDN'T START HIM DOWN ALL THE WAY. MIL X ROGERED MY CLRNC AND SAID 'DSNDING TO 8000.' I GAVE HIM AN ALTIMETER AND SAID, 'I'M GOING TO HAVE TO HAVE YOU DOWN TO 7000 BY ABOUT STE.' I WAITED A FEW SECONDS AND MIL X NEVER GAVE ANY REPLY. I THEN WENT TO THE XING TFC AT 7000 FT AND ISSUED THEM LOWER ALTS. MY D-SIDE WAS BUSY COORDINATING WITH OTHER FACILITIES, SO I HAD TO DO SOME COORDINATION WITH A VFR TWR IN MY SECTOR BESIDES ANSWERING NUMEROUS CALLS FROM OTHER ACFT. RIGHT AROUND STE, MIL X CHKED LEVEL AT 7000 FT. THE CONFLICTING ACFT, A SINGLE ENG CESSNA HAD JUST CHKED OUT OF 7000 FT. THERE WAS ONLY A COUPLE HUNDRED FEET SEPARATION AND MAYBE 2 MI. I TOLD THE MIL X I HAD ONLY ISSUED HIM 8000 FT AND CLBED HIM BACK UP TO 800 FT AND GAVE HIM A 90 DEG TURN. AFTER LISTENING TO THE TAPES, I REALIZE THE MIL X HAD TRIED TO CALL ME, BUT DUE TO FREQ CONGESTION AND MY BEING ON THE LANDLINE, I NEVER HEARD HIM. I REALIZE MY POOR PHRASEOLOGY CONFUSED MIL X BUT I ALSO THINK PLTS NEED TO BE REMINDED THAT UNLESS THE TERMS 'DSND AND MAINTAIN, CLB AND MAINTAIN OR CROSS AT AND MAINTAIN' ARE USED THERE IS NO NEW ALT CLRNC.

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.