Narrative:

During descent into toronto the student captain receiving operating experience, misunderstood the clearance from toronto approach and leveled at 7000 ft MSL instead of 9000 ft MSL. At the time the clearance was issued, I was off the frequency checking the ATIS information. When I came back onto the approach frequency the student captain had set 7000 ft MSL in the MCP window and told me we were cleared to 7000 ft MSL. Approach control asked about our altitude level and I responded '7000 ft MSL.' what caused me to rechk the ATIS information was the initial ATIS information stated that runway 15 was the arrival runway, but we were given the profile descent approach for runway 24L. I questioned approach as to what runway they were actually using. Reply was runway 24L. This required a new selection on the FMC panel during a high workload phase of flight. Canadian accents, plus the different expressions of instructions, also contributed to this confusion. Slower transmission of instructions and clrncs would help in alleviating some of the miscommunication problems.

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Original NASA ASRS Text

Title: ALTDEV ALT OVERSHOT IN DSCNT AS STUDENT CAPT HAS A PROB WITH CLRNC INTERP READBACK HEARBACK. OPDEV AS APCH CTLR TECHNIQUE ATC COM FAILS TO CATCH ERROR.

Narrative: DURING DSCNT INTO TORONTO THE STUDENT CAPT RECEIVING OPERATING EXPERIENCE, MISUNDERSTOOD THE CLRNC FROM TORONTO APCH AND LEVELED AT 7000 FT MSL INSTEAD OF 9000 FT MSL. AT THE TIME THE CLRNC WAS ISSUED, I WAS OFF THE FREQ CHKING THE ATIS INFO. WHEN I CAME BACK ONTO THE APCH FREQ THE STUDENT CAPT HAD SET 7000 FT MSL IN THE MCP WINDOW AND TOLD ME WE WERE CLRED TO 7000 FT MSL. APCH CTL ASKED ABOUT OUR ALT LEVEL AND I RESPONDED '7000 FT MSL.' WHAT CAUSED ME TO RECHK THE ATIS INFO WAS THE INITIAL ATIS INFO STATED THAT RWY 15 WAS THE ARR RWY, BUT WE WERE GIVEN THE PROFILE DSCNT APCH FOR RWY 24L. I QUESTIONED APCH AS TO WHAT RWY THEY WERE ACTUALLY USING. REPLY WAS RWY 24L. THIS REQUIRED A NEW SELECTION ON THE FMC PANEL DURING A HIGH WORKLOAD PHASE OF FLT. CANADIAN ACCENTS, PLUS THE DIFFERENT EXPRESSIONS OF INSTRUCTIONS, ALSO CONTRIBUTED TO THIS CONFUSION. SLOWER TRANSMISSION OF INSTRUCTIONS AND CLRNCS WOULD HELP IN ALLEVIATING SOME OF THE MISCOMMUNICATION PROBS.

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.