Narrative:

Was cleared to 10000 ft MSL by departure control. After reaching 10000 ft MSL, I mistakenly believed I was cleared to a higher altitude, and reduced rate of climb to 500 FPM to allow aircraft to accelerate from the 250 KT speed limit to a climb speed of 310 KTS. At 10300 ft MSL, a TCASII alert sounded, commanding 'reduce vertical speed.' the TCASII command was loud enough to mask the aural warning of the altitude alerter. The TCASII display showed the conflicting traffic to be at approximately the 1:30 O'clock position and 8 NM and plus 800 ft. I stopped the climb at 10350 ft MSL, and now beginning to suspect that I might be in error as to altitude, I began to look for the altitude alerter for confirmation. Locating the altitude reminder took more time than desired due to non-standardization of alerter panel location within our fleet -- no fewer than 3 locations. After locating the altitude alerter, and noting it read 10000 ft, I returned immediately to assigned altitude. Require standardized panel location of altitude alerter. Tighten warning band of altitude alerter. Develop altitude alerter that senses rate of climb/descent existing as aircraft nears assigned altitude, and can adjust hardness of warning. Either reduce TCASII audio volume or install some type of logic to prioritize TCASII and altitude alerter warnings (or sequence them), so that they do not blank one another.

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Original NASA ASRS Text

Title: AN ACR LGT PLT CLBED ABOVE ITS ASSIGNED ALT CAUSING A TCASII ALERT.

Narrative: WAS CLRED TO 10000 FT MSL BY DEP CTL. AFTER REACHING 10000 FT MSL, I MISTAKENLY BELIEVED I WAS CLRED TO A HIGHER ALT, AND REDUCED RATE OF CLB TO 500 FPM TO ALLOW ACFT TO ACCELERATE FROM THE 250 KT SPD LIMIT TO A CLB SPD OF 310 KTS. AT 10300 FT MSL, A TCASII ALERT SOUNDED, COMMANDING 'REDUCE VERT SPD.' THE TCASII COMMAND WAS LOUD ENOUGH TO MASK THE AURAL WARNING OF THE ALT ALERTER. THE TCASII DISPLAY SHOWED THE CONFLICTING TFC TO BE AT APPROX THE 1:30 O'CLOCK POS AND 8 NM AND PLUS 800 FT. I STOPPED THE CLB AT 10350 FT MSL, AND NOW BEGINNING TO SUSPECT THAT I MIGHT BE IN ERROR AS TO ALT, I BEGAN TO LOOK FOR THE ALT ALERTER FOR CONFIRMATION. LOCATING THE ALT REMINDER TOOK MORE TIME THAN DESIRED DUE TO NON-STANDARDIZATION OF ALERTER PANEL LOCATION WITHIN OUR FLEET -- NO FEWER THAN 3 LOCATIONS. AFTER LOCATING THE ALT ALERTER, AND NOTING IT READ 10000 FT, I RETURNED IMMEDIATELY TO ASSIGNED ALT. REQUIRE STANDARDIZED PANEL LOCATION OF ALT ALERTER. TIGHTEN WARNING BAND OF ALT ALERTER. DEVELOP ALT ALERTER THAT SENSES RATE OF CLB/DSCNT EXISTING AS ACFT NEARS ASSIGNED ALT, AND CAN ADJUST HARDNESS OF WARNING. EITHER REDUCE TCASII AUDIO VOLUME OR INSTALL SOME TYPE OF LOGIC TO PRIORITIZE TCASII AND ALT ALERTER WARNINGS (OR SEQUENCE THEM), SO THAT THEY DO NOT BLANK ONE ANOTHER.

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.