AN SMA PHOTO PLT FLEW WELL ABOVE HIS ACFT'S SVC CEILING INTO THE 'COFFIN CORNER.'

Narrative

WERE FLYING A PHOTO MISSION AT FL210. WERE EXPERIENCING LIGHT TO MODERATE TURB. ACFT ENCOUNTERED DOWNDRAFT. LOST 30 KTS AIRSPD; HOWEVER ACFT SOON RECOVERED AND ONLY LOST 100 FT OF ALT. A SHORT TIME LATER; ACFT ENCOUNTERED ANOTHER DOWNDRAFT. THIS TIME THE ACFT LOST 40 KTS; AND I WAS UNABLE TO CTL ALT. I CALLED CTR WHEN I WAS 200 FT LOW AND ADVISED THEM THAT I COULD NOT MAINTAIN ALT. I THEN BROKE THE 300 FT LIMIT. I WAS INDICATING 80 KTS AIRSPD AND IN A 350 TO 400 FPM DSCNT. CTR CLRED ME TO FL190 AND A HDG OF 030. I REQUESTED DIRECT ROA AND WAS GIVEN DIRECT AND DOWN TO 14000 FT. WHEN WE LANDED; ZDC CALLED AND ADVISED THAT THEY WERE INVESTIGATING THE ALTDEV. A FEW MINS LATER (10-15); THEY CALLED BACK AND SAID NO VIOLATION HAD OCCURRED SINCE THEY CONSIDERED IT AN EMER. THE FAA CTR MAN WAS GOOD AS FAR AS ATTITUDE; AND WAS HELPFUL. THE MAIN REASON FOR WRITING THIS IS BASICALLY TO CYA. HOWEVER; THERE ARE ALSO SOME ADDITIONAL FACTORS. THE COMPANY I FLY FOR IS ALWAYS PUSHING US TO FLY AN ACFT THAT IS UNDERPWRED AT THAT ALT.