ZMA CTLR DESCRIBED EVENT WHEN ACFT FILED FOR FL430 BUT WAS UNABLE TO REACH ALT; ALLEGING FLT CREW FILED INAPPROPRIATE ALT.

Narrative

ACFT X; AN LJ35/G NEGATIVE RVSM; REQUESTED FL430. ZJX APPROVED ENTERING AIRSPACE LEVEL AT FL430. TFC WAS MODERATE TO HVY AT BOTH XFERRING AND RECEIVING SECTORS. SE OF THE ORL VOR ACFT REDUCED RATE OF CLB TO LESS THAN 500 FPM. ZJX CTLR CALLED REQUESTING ACFT TO INCREASE RATE OF CLB SO AS TO BE LEVEL AT FL430 AT THE BOUNDARY. I ADVISED THE ACFT TO DO SO; AT WHICH TIME THE PLT OF ACFT X STATED HE COULD NOT. I INITIATED A RADAR VECTOR TO ALLOW THE ACFT MORE TIME TO CLB AND ADVISED THE ZJX CTLR. SHORTLY AFTER; THE ACFT APPEARED TO HAVE REDUCED THE RATE OF CLB EVEN FURTHER. I NOTIFIED THE FRONT LINE MGR THAT I MAY HAVE A SITUATION DEVELOPING AND WAS CONCERNED THAT THE ACFT MAY STALL. THE FLM CONTACTED ZJX WHO AGREED TO ACCEPT THE ACFT. I OBSERVED THE ACFT LEVEL AT FL420 FOR A MINIMUM OF 35 MI. IT IS MY PROFESSIONAL OPINION THAT THE ACFT WAS NOT ABLE TO REACH FL430 AND FILED THE ALT AS A MEANS TO UTILIZE RVSM AIRSPACE WHEN NOT PROPERLY CERTIFIED TO DO SO. AS A RESULT; THE ACFT ENDED UP HAVING TO LEVEL AT AN ALT THAT IS NOT ASSIGNABLE IN ANY INSTANCE (FL420).