Narrative:

During climb out from ewr, we had received several step-climb and change of heading clrncs from ATC. We were in a climb to FL210. After switching to ZBW, we were given a clearance of 'turn right 040 degrees, maintain 2-5-0.' the first officer, responded to the controller, 'heading 040, climb to 2-5-0.' at about FL237, during the climb, the controller told us to descend to FL210. He said we had not been cleared to FL250. He then asked if we were maintaining 250 KTS. We were not, as we had not been issued this restr. We were asked to slow to 250 KTS, and we complied with all further instructions. I believe this occurrence could have been avoided had the controller used clrer, standard radio phraseology. There may also have been some confusion to him as to our clearance on the handoff from the previous sector. To my knowledge, no traffic conflict was involved. Supplemental information from acn 428344: controller used 2-5-0 instead of FL250. I read back climbing to 2-5-0 and he did not correct me. Using 2-5-0 indicates an altitude to me and 250 KTS means airspeed. Supplemental information from acn 428184: as so (flight engineer) I was contacting bos ATIS and bos ramp at this time. When I got off the radio with bos ramp the front enders were descending back down to FL210.

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Original NASA ASRS Text

Title: A DC10-30 FREIGHTER CLBS TOWARDS FL250 WHEN THE FLT HAD BEEN ASSIGNED A '2-5-0' BY ZBW CTLR. CTLR MEANT KTS, BUT THE CREW THOUGHT IT WAS A FLT LEVEL.

Narrative: DURING CLBOUT FROM EWR, WE HAD RECEIVED SEVERAL STEP-CLB AND CHANGE OF HDG CLRNCS FROM ATC. WE WERE IN A CLB TO FL210. AFTER SWITCHING TO ZBW, WE WERE GIVEN A CLRNC OF 'TURN R 040 DEGS, MAINTAIN 2-5-0.' THE FO, RESPONDED TO THE CTLR, 'HDG 040, CLB TO 2-5-0.' AT ABOUT FL237, DURING THE CLB, THE CTLR TOLD US TO DSND TO FL210. HE SAID WE HAD NOT BEEN CLRED TO FL250. HE THEN ASKED IF WE WERE MAINTAINING 250 KTS. WE WERE NOT, AS WE HAD NOT BEEN ISSUED THIS RESTR. WE WERE ASKED TO SLOW TO 250 KTS, AND WE COMPLIED WITH ALL FURTHER INSTRUCTIONS. I BELIEVE THIS OCCURRENCE COULD HAVE BEEN AVOIDED HAD THE CTLR USED CLRER, STANDARD RADIO PHRASEOLOGY. THERE MAY ALSO HAVE BEEN SOME CONFUSION TO HIM AS TO OUR CLRNC ON THE HDOF FROM THE PREVIOUS SECTOR. TO MY KNOWLEDGE, NO TFC CONFLICT WAS INVOLVED. SUPPLEMENTAL INFO FROM ACN 428344: CTLR USED 2-5-0 INSTEAD OF FL250. I READ BACK CLBING TO 2-5-0 AND HE DID NOT CORRECT ME. USING 2-5-0 INDICATES AN ALT TO ME AND 250 KTS MEANS AIRSPD. SUPPLEMENTAL INFO FROM ACN 428184: AS SO (FE) I WAS CONTACTING BOS ATIS AND BOS RAMP AT THIS TIME. WHEN I GOT OFF THE RADIO WITH BOS RAMP THE FRONT ENDERS WERE DSNDING BACK DOWN TO FL210.

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.