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Air carrier medium large transport acftþs central air data computer equipment failed causing, among other problems, an erroneous transponder altitude reading to ATC.
| Attributes | |
| ACN | 206847 |
| Time | |
| Date | 199204 |
| Day | Mon |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : cle |
| State Reference | OH |
| Altitude | msl bound lower : 6000 msl bound upper : 6500 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : cle tracon : dfw |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | climbout : intermediate altitude |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 18000 flight time type : 10000 |
| ASRS Report | 206847 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : less severe non adherence : far non adherence : published procedure |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa |
| Resolutory Action | none taken : anomaly accepted |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
On climb out of cle, CADC failure causing GPWS giving commands to þpull upþ (false). Captþs altimeter went to barometric flag (green) in view, mach trim fail light on, red flag in altitude alert system and #1 and #2 transponder altitude reporting showing 500-800 ft difference from aircraft actual. Controller stated he showed þalt bustþ at 6500 ft MSL when in fact the aircraft was at 6000 MSL, which was assigned because of other traffic at 7000 ft MSL. Handed over to þcle ctrþ and they showed the same errors as departure control. Requested transponder altitude reporting off, but they wanted to keep it on for identity to cruise altitude. Got so bad that they (ATC) requested transponder altitude reporting off, and we continued to mke with mode þcþ inoperative (i.e., turned off)!
Original NASA ASRS Text
Title: ACR MLG ACFTþS CENTRAL AIR DATA COMPUTER EQUIP FAILED CAUSING, AMONG OTHER PROBLEMS, AN ERRONEOUS TRANSPONDER ALT READING TO ATC.
Narrative: ON CLBOUT OF CLE, CADC FAILURE CAUSING GPWS GIVING COMMANDS TO þPULL UPþ (FALSE). CAPTþS ALTIMETER WENT TO BAROMETRIC FLAG (GREEN) IN VIEW, MACH TRIM FAIL LIGHT ON, RED FLAG IN ALT ALERT SYS AND #1 AND #2 TRANSPONDER ALT RPTING SHOWING 500-800 FT DIFFERENCE FROM ACFT ACTUAL. CTLR STATED HE SHOWED þALT BUSTþ AT 6500 FT MSL WHEN IN FACT THE ACFT WAS AT 6000 MSL, WHICH WAS ASSIGNED BECAUSE OF OTHER TFC AT 7000 FT MSL. HANDED OVER TO þCLE CTRþ AND THEY SHOWED THE SAME ERRORS AS DEP CTL. REQUESTED TRANSPONDER ALT RPTING OFF, BUT THEY WANTED TO KEEP IT ON FOR IDENTITY TO CRUISE ALT. GOT SO BAD THAT THEY (ATC) REQUESTED TRANSPONDER ALT RPTING OFF, AND WE CONTINUED TO MKE WITH MODE þCþ INOP (I.E., TURNED OFF)!
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.