Narrative:

Air carrier X cruise altitude FL350 and in the cloud tops I requested altitude change to FL390 to get away from light turbulence. Shortly after starting the climb the main bleed on my left engine malfunctioned and closed thereby shutting down one of the air conditioning packs. To comply with the aircraft limitations (one pack operation, maximum altitude FL350) I requested reclrnc back to FL350, which I was granted. Upon reaching FL350 I was given instruction to turn left which I did. Shortly thereafter I was given clearance to proceed direct to a downline waypoint which was listed on the flight plan. At this point the controller asked the reason for my request to descend to FL350 and I explained the operational necessity to him. I was then told to call the cle center supervisor at the completion of my flight which I did. She told me that they would begin an internal quality control investigation. During my conversation with the watch supervisor I was told that my flight path was converging with another aircraft Y that was climbing to FL350. Supplemental information from acn 139235. When we left FL350 the 1ST time they also cleared aircraft Y up to our altitude. When we started our descent we were given a heading of 250 degree to fly. We used heading select and the aircraft started a slow turn to the left. I heard aircraft Y receive a heading change also but not an altitude change. (I might add that the controller told aircraft Y we were unable to hold our requested altitude of FL390, using a tone that to me implied we had asked for an altitude we thought we could reach but later found couldn't due to a mistake on our part). While coming to FL250 we were then cleared back direct course grb. Our heading was approximately 260 degree. While in this turn ATC then asked us 'what is your heading'. We told them we were in a turn coming back to grb as cleared. They acknowledged that this was what we were cleared to do yet seemed highly agitated. Then they told us we had a pilot deviation and to call the cleveland ATC supervisor on landing.

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Original NASA ASRS Text

Title: ACR X HAD EQUIPMENT PROBLEM REQUESTED AMENDED ATC CLRNC AND HAD LESS THAN STANDARD SEPARATION FROM ACFT Y.

Narrative: ACR X CRUISE ALT FL350 AND IN THE CLOUD TOPS I REQUESTED ALT CHANGE TO FL390 TO GET AWAY FROM LIGHT TURB. SHORTLY AFTER STARTING THE CLB THE MAIN BLEED ON MY L ENG MALFUNCTIONED AND CLOSED THEREBY SHUTTING DOWN ONE OF THE AIR CONDITIONING PACKS. TO COMPLY WITH THE ACFT LIMITATIONS (ONE PACK OPERATION, MAX ALT FL350) I REQUESTED RECLRNC BACK TO FL350, WHICH I WAS GRANTED. UPON REACHING FL350 I WAS GIVEN INSTRUCTION TO TURN L WHICH I DID. SHORTLY THEREAFTER I WAS GIVEN CLRNC TO PROCEED DIRECT TO A DOWNLINE WAYPOINT WHICH WAS LISTED ON THE FLT PLAN. AT THIS POINT THE CTLR ASKED THE REASON FOR MY REQUEST TO DSND TO FL350 AND I EXPLAINED THE OPERATIONAL NECESSITY TO HIM. I WAS THEN TOLD TO CALL THE CLE CENTER SUPVR AT THE COMPLETION OF MY FLT WHICH I DID. SHE TOLD ME THAT THEY WOULD BEGIN AN INTERNAL QUALITY CTL INVESTIGATION. DURING MY CONVERSATION WITH THE WATCH SUPVR I WAS TOLD THAT MY FLT PATH WAS CONVERGING WITH ANOTHER ACFT Y THAT WAS CLBING TO FL350. SUPPLEMENTAL INFO FROM ACN 139235. WHEN WE LEFT FL350 THE 1ST TIME THEY ALSO CLRED ACFT Y UP TO OUR ALT. WHEN WE STARTED OUR DSCNT WE WERE GIVEN A HDG OF 250 DEG TO FLY. WE USED HDG SELECT AND THE ACFT STARTED A SLOW TURN TO THE L. I HEARD ACFT Y RECEIVE A HDG CHANGE ALSO BUT NOT AN ALT CHANGE. (I MIGHT ADD THAT THE CTLR TOLD ACFT Y WE WERE UNABLE TO HOLD OUR REQUESTED ALT OF FL390, USING A TONE THAT TO ME IMPLIED WE HAD ASKED FOR AN ALT WE THOUGHT WE COULD REACH BUT LATER FOUND COULDN'T DUE TO A MISTAKE ON OUR PART). WHILE COMING TO FL250 WE WERE THEN CLRED BACK DIRECT COURSE GRB. OUR HDG WAS APPROX 260 DEG. WHILE IN THIS TURN ATC THEN ASKED US 'WHAT IS YOUR HDG'. WE TOLD THEM WE WERE IN A TURN COMING BACK TO GRB AS CLRED. THEY ACKNOWLEDGED THAT THIS WAS WHAT WE WERE CLRED TO DO YET SEEMED HIGHLY AGITATED. THEN THEY TOLD US WE HAD A PLT DEV AND TO CALL THE CLEVELAND ATC SUPVR ON LNDG.

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.