A BE40'S CLB RATE AND SPD ABOVE FL360 CLBING TO FL380 DECREASED TO THE POINT THAT OTHER NORMALLY PERFORMING RVSM ACFT WERE DISRUPTED.

Narrative

WE WERE CLBING TO OUR ASSIGNED ALT OF FL380 AT A FAIRLY GOOD RATE OF 1500 FPM. TEMPERATURES WERE HOLDING AND OUR WT; ALTHOUGH HEAVY; WAS WITHIN THE PERFORMANCE PARAMETERS OF THE AIRPLANE. CLBING THROUGH FL360; WE NOTICED THAT THE CLB PERF WAS SUFFERING AND THE INDICATED AIRSPEED WAS DETERIORATING. THE CLB RATE WAS SHALLOWED TO 500 FPM IN ORDER TO REACH FL380. AT THIS POINT; WE NOTICED THAT THE CLB/RATE LEVELED OUT AT 0 FPM AND THE INDICATED AIRSPEED WAS EXTREMELY SLOW. POWER WAS INCREASED 2 PERCENT TO MAXIMUM AND THE CLB WAS RE-ESTABLISHED AT A RATE OF 500 FPM UNTIL LEVELING OFF AT FL380. THE AUTOPILOT WAS IN USE AT ALL TIMES. WHAT CAUSED THE PROB WAS CONTINUING TO SEEK AN AGGRESSIVE CLB RATE ABOVE FL300. WHAT CAN BE DONE TO PREVENT A RECURRENCE IS TO MORE CLOSELY MONITOR OUTSIDE AIR TEMPERATURES AT 1000 FOOT INTERVALS IN THE CLB AND/OR WHENEVER AT HIGHER ALTITUDE AND INDICATED AIRSPEEDS ARE SLOWER THAN 200 KIAS. WE WERE ADVISED TO CONTACT MIAMI WATCH -- WHICH WE DID UPON LNDG -- AND WERE TOLD THAT THIS WAS AN ISSUE BECAUSE AN A319 WAS CLBING BEHIND US AND THE 1000 FOOT SEPARATION WAS NOT ABLE TO BE MAINTAINED AND; AS OUR AIRSPEED SLOWED; THE OTHER ACFT GAINED ON US AND THE AIRSPEED DIFFERENCE INCREASED FROM 50 KTS TO 140 KTS WHILE THE DISTANCE BETWEEN ACFT DECREASED TO 4.48 MILES; AND THE ALTITUDE SEPARATION WAS REDUCED TO 800 FT. WHILE RVSM IS GREAT; MAYBE IT SHOULD ONLY BE USED WHEN BOTH ACFT ARE LEVEL OR -- AT LEAST -- ONLY ONE IS CLBING OR DESCENDING? THIS MATTER WAS RESOLVED OVER THE TELEPHONE WITH MIAMI WATCH AND THEY INDICATED THAT NO PILOT DEVIATION RPT WOULD BE FILED. WE APPRECIATE BEING ABLE TO WORK THIS OUT AMICABLY.