The service ceiling of an aircraft is defined as the altitude where the aircraft is no longer able to sustain a certain minimum rate of climb. (Wikipedia suggests 100 ft/sec).
Ha! I think by that defination, most SEP's would have reached their service ceiling at sea level!
I think the more normal defination of service ceiling is 100ft/minute (...though I have 50/min in the back of my mind for some reason)
