Narrative:

Upon crossing deer park dpk turning to a 053 heading, ZBW issued a descent to 'cross madison at 10,000 at 250 KTS and an altimeter setting'. I read back cross madison at 'ten/two-fifty' and the altimeter setting. The captain, moments later, asked me to confirm the altitude and speed, which I did, by inquiring 'does xx need to be at 250 at ten at madison?' I was answered yes by ZBW. At approximately 604 DME from madison at an altitude of 10,400', boston inquired as to whether we were at 11,000. I replied we were descending to 10,000'. ZBW stated to immediately climb to 11,000, which we complied with, immediately. ZBW then issued a heading of 360 to intercept route north of madison (radial 235 mad) to (360 degree right mad). I have been a reader of 'callback' for some time. In conversing with controllers while 'off duty' I learned that they are taught to say one-zero thousand or one-one thousand instead of ten or eleven thousand. I decided to adopt this phraseology. In repeating or rather reading back my initial clearance of (ten/two-fifty) I feel that ten was acceptable and was unmistakable with eleven. The controller did not disagree with ten/two-fifty, therefore without a negative response for the readback, I assumed I was correct with 10,000/250 KTS. In the future, I shall read back ten-one zero thousand in an attempt to clarify and catch any mistakes, misunderstandings or slip-ups. The particular STAR-dpk-1 does not advise to expect 11,000/250 but other STAR-roda-5 does specify such a crossing restriction. Controllers are used to 10/250 repeats and he probably let it slide thru, thinking of the 11/250. If I had stated ten-one zero thousand, we both would have caught the mistake.

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Original NASA ASRS Text

Title: ALT DEVIATION BY FLT CREW OF MLG BECAUSE OF MISUNDERSTANDING OF 10,000 - 11,000.

Narrative: UPON XING DEER PARK DPK TURNING TO A 053 HDG, ZBW ISSUED A DSCNT TO 'CROSS MADISON AT 10,000 AT 250 KTS AND AN ALTIMETER SETTING'. I READ BACK CROSS MADISON AT 'TEN/TWO-FIFTY' AND THE ALTIMETER SETTING. THE CAPT, MOMENTS LATER, ASKED ME TO CONFIRM THE ALT AND SPEED, WHICH I DID, BY INQUIRING 'DOES XX NEED TO BE AT 250 AT TEN AT MADISON?' I WAS ANSWERED YES BY ZBW. AT APPROX 604 DME FROM MADISON AT AN ALT OF 10,400', BOSTON INQUIRED AS TO WHETHER WE WERE AT 11,000. I REPLIED WE WERE DESCENDING TO 10,000'. ZBW STATED TO IMMEDIATELY CLIMB TO 11,000, WHICH WE COMPLIED WITH, IMMEDIATELY. ZBW THEN ISSUED A HDG OF 360 TO INTERCEPT ROUTE N OF MADISON (RADIAL 235 MAD) TO (360 DEG R MAD). I HAVE BEEN A READER OF 'CALLBACK' FOR SOME TIME. IN CONVERSING WITH CTLRS WHILE 'OFF DUTY' I LEARNED THAT THEY ARE TAUGHT TO SAY ONE-ZERO THOUSAND OR ONE-ONE THOUSAND INSTEAD OF TEN OR ELEVEN THOUSAND. I DECIDED TO ADOPT THIS PHRASEOLOGY. IN REPEATING OR RATHER READING BACK MY INITIAL CLRNC OF (TEN/TWO-FIFTY) I FEEL THAT TEN WAS ACCEPTABLE AND WAS UNMISTAKABLE WITH ELEVEN. THE CTLR DID NOT DISAGREE WITH TEN/TWO-FIFTY, THEREFORE WITHOUT A NEGATIVE RESPONSE FOR THE READBACK, I ASSUMED I WAS CORRECT WITH 10,000/250 KTS. IN THE FUTURE, I SHALL READ BACK TEN-ONE ZERO THOUSAND IN AN ATTEMPT TO CLARIFY AND CATCH ANY MISTAKES, MISUNDERSTANDINGS OR SLIP-UPS. THE PARTICULAR STAR-DPK-1 DOES NOT ADVISE TO EXPECT 11,000/250 BUT OTHER STAR-RODA-5 DOES SPECIFY SUCH A XING RESTRICTION. CTLRS ARE USED TO 10/250 REPEATS AND HE PROBABLY LET IT SLIDE THRU, THINKING OF THE 11/250. IF I HAD STATED TEN-ONE ZERO THOUSAND, WE BOTH WOULD HAVE CAUGHT THE MISTAKE.

Data retrieved from NASA's ASRS site as of August 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.