Narrative:

On climb out from runway 23R my captain and I were given a heading of 320 degrees up to 5000 ft MSL. We were told to stop at 5000 ft in order to let crossing traffic clear which was at an altitude of 6000 ft MSL heading wbound. The aircraft's position was at our 1 O'clock position, showing +800 ft above us based on our traffic alert TCASII system. Upon reaching 5000 ft, the indianapolis departure control gave us a warning saying that our aircraft was showing 5300 ft MSL, and we were approaching the wbound traffic. At the present time our altitude was reading 5100 ft MSL which was calibrated within 75 ft at sea level to give us a correct altitude reading of 5000 ft MSL. At this exact time of the warning the wbound traffic was still at 6000 ft MSL and our 5 O'clock position. Also the wbound traffic at that same time called indianapolis departure stating that traffic was in sight and no factor. The ending result was that no evasive action or aircraft deviation was necessary by either aircraft. The ending factor could have been a false altitude alert on the indy departure radar or the altimeters giving a false readout which needs to be checked.

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Original NASA ASRS Text

Title: SH36 FLT CREW IS QUESTIONED BY IND TRACON REGARDING THEIR ALT INDICATION WHICH WAS 300 FT ABOVE THE ASSIGNED 5000 FT, TCASII TA RECEIVED.

Narrative: ON CLBOUT FROM RWY 23R MY CAPT AND I WERE GIVEN A HDG OF 320 DEGS UP TO 5000 FT MSL. WE WERE TOLD TO STOP AT 5000 FT IN ORDER TO LET XING TFC CLR WHICH WAS AT AN ALT OF 6000 FT MSL HDG WBOUND. THE ACFT'S POS WAS AT OUR 1 O'CLOCK POS, SHOWING +800 FT ABOVE US BASED ON OUR TFC ALERT TCASII SYS. UPON REACHING 5000 FT, THE INDIANAPOLIS DEP CTL GAVE US A WARNING SAYING THAT OUR ACFT WAS SHOWING 5300 FT MSL, AND WE WERE APCHING THE WBOUND TFC. AT THE PRESENT TIME OUR ALT WAS READING 5100 FT MSL WHICH WAS CALIBRATED WITHIN 75 FT AT SEA LEVEL TO GIVE US A CORRECT ALT READING OF 5000 FT MSL. AT THIS EXACT TIME OF THE WARNING THE WBOUND TFC WAS STILL AT 6000 FT MSL AND OUR 5 O'CLOCK POS. ALSO THE WBOUND TFC AT THAT SAME TIME CALLED INDIANAPOLIS DEP STATING THAT TFC WAS IN SIGHT AND NO FACTOR. THE ENDING RESULT WAS THAT NO EVASIVE ACTION OR ACFT DEV WAS NECESSARY BY EITHER ACFT. THE ENDING FACTOR COULD HAVE BEEN A FALSE ALT ALERT ON THE INDY DEP RADAR OR THE ALTIMETERS GIVING A FALSE READOUT WHICH NEEDS TO BE CHKED.

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.