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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Small aircraft aircraft transiting class B airspace under positive ATC control. Reporter pilot was instructed to maintain 3500 ft, approach controller reminded pilot to maintain 3500 ft when the controller was showing 4000 ft on his altitude readout. Reporter confirmed current altimeter and still showed altitude of 3500 ft. Eventually controller had reporter turn off his erroneous transponder due to altitude reporting error of 500 ft.
| Attributes | |
| ACN | 366000 |
| Time | |
| Date | 199704 |
| Day | Thu |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : msp |
| State Reference | MN |
| Altitude | msl bound lower : 3500 msl bound upper : 4000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : msp |
| Operator | general aviation : personal |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise other |
| Flight Plan | None |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : atp pilot : cfi pilot : instrument |
| Experience | flight time last 90 days : 50 flight time total : 4000 flight time type : 300 |
| ASRS Report | 366000 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Events | |
| Anomaly | aircraft equipment problem : less severe other anomaly other |
| Independent Detector | other controllera |
| Resolutory Action | other other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
Cleared to enter msp class B airspace and told to climb to 3500 ft MSL. Upon leveloff, msp approach advised me that I was cleared to 3500 ft, not 4000 ft which is what they were showing me at on radar. I confirmed the current altimeter setting and verified that I was level at 3500 ft MSL indicated. Suspecting transponder encoding error, I asked if they would like me to exit the class B or continue as originally requested. Approach cleared me to continue through the class B at 3500 ft MSL indicated. I am submitting this report due to the location (over msp airport) and any TCASII advisories it may have caused. I was not told to stop altitude squawk until directly over the msp airport. Due to the apparent transponder encoding error on the aircraft I was flying, I don't think I could have done anything different. However, since the controller cleared me to continue on course at 3500 ft MSL indicated, I was surprised that I was not told to stop altitude squawk immediately and continue VFR reporting. The transponder encoding error was large (between 400-500 ft).
Original NASA ASRS Text
Title: SMA ACFT TRANSITING CLASS B AIRSPACE UNDER POSITIVE ATC CTL. RPTR PLT WAS INSTRUCTED TO MAINTAIN 3500 FT, APCH CTLR REMINDED PLT TO MAINTAIN 3500 FT WHEN THE CTLR WAS SHOWING 4000 FT ON HIS ALT READOUT. RPTR CONFIRMED CURRENT ALTIMETER AND STILL SHOWED ALT OF 3500 FT. EVENTUALLY CTLR HAD RPTR TURN OFF HIS ERRONEOUS XPONDER DUE TO ALT RPTING ERROR OF 500 FT.
Narrative: CLRED TO ENTER MSP CLASS B AIRSPACE AND TOLD TO CLB TO 3500 FT MSL. UPON LEVELOFF, MSP APCH ADVISED ME THAT I WAS CLRED TO 3500 FT, NOT 4000 FT WHICH IS WHAT THEY WERE SHOWING ME AT ON RADAR. I CONFIRMED THE CURRENT ALTIMETER SETTING AND VERIFIED THAT I WAS LEVEL AT 3500 FT MSL INDICATED. SUSPECTING XPONDER ENCODING ERROR, I ASKED IF THEY WOULD LIKE ME TO EXIT THE CLASS B OR CONTINUE AS ORIGINALLY REQUESTED. APCH CLRED ME TO CONTINUE THROUGH THE CLASS B AT 3500 FT MSL INDICATED. I AM SUBMITTING THIS RPT DUE TO THE LOCATION (OVER MSP ARPT) AND ANY TCASII ADVISORIES IT MAY HAVE CAUSED. I WAS NOT TOLD TO STOP ALT SQUAWK UNTIL DIRECTLY OVER THE MSP ARPT. DUE TO THE APPARENT XPONDER ENCODING ERROR ON THE ACFT I WAS FLYING, I DON'T THINK I COULD HAVE DONE ANYTHING DIFFERENT. HOWEVER, SINCE THE CTLR CLRED ME TO CONTINUE ON COURSE AT 3500 FT MSL INDICATED, I WAS SURPRISED THAT I WAS NOT TOLD TO STOP ALT SQUAWK IMMEDIATELY AND CONTINUE VFR RPTING. THE XPONDER ENCODING ERROR WAS LARGE (BTWN 400-500 FT).
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.