 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
A B737-200 flying in ZAU airspace, reads back the wrong altitude they were cleared to. After a 1500 ft deviation, the controller notices the deviation and reclears the aircraft back to a lower altitude. Controller allegedly states he did not hear the erroneous readback.
| Attributes | |
| ACN | 375064 |
| Time | |
| Date | 199707 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : jot |
| State Reference | IL |
| Altitude | msl bound lower : 31000 msl bound upper : 32500 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | climbout : intermediate altitude |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : instrument pilot : atp pilot : commercial |
| Experience | flight time last 90 days : 163 flight time total : 14081 flight time type : 4000 |
| ASRS Report | 375064 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time total : 5900 flight time type : 210 |
| ASRS Report | 375500 |
| Events | |
| Anomaly | altitude deviation : overshoot other anomaly other |
| Independent Detector | atc equipment other atc equipment : unspecified other controllera |
| Resolutory Action | controller : issued new clearance flight crew : returned to intended course or assigned course other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | other |
Narrative:
While climbing from an intermediate altitude of FL290 to FL330, the center controller asked what altitude we were cleared to. When we responded 'FL330,' he asked us to level off at our present altitude and we leveled off at FL325. After about 30 seconds, he stated that he had cleared us to FL310 and may have missed our readback of 'FL330.' he reclred us to FL310, and we descended to FL310. Both of us on the flight deck had understood our clearance to be FL330 and I had set FL330 in the altitude alert panel, since I was flying, using the autoflt system. We do not know if we misheard the clearance or the controller mistakenly cleared us to the wrong altitude. There was no apparent traffic conflict. Supplemental information from acn 375500: ZAU cleared us to FL330. This seemed odd, first officer read back FL330, captain set FL330 in MCP after verbalizing clearance. At approximately FL321 ZAU asked what altitude we were cleared to, we said FL330. Center said stop climb at FL320, then reclred us back to FL310. Center said he missed the readback.
Original NASA ASRS Text
Title: A B737-200 FLYING IN ZAU AIRSPACE, READS BACK THE WRONG ALT THEY WERE CLRED TO. AFTER A 1500 FT DEV, THE CTLR NOTICES THE DEV AND RECLEARS THE ACFT BACK TO A LOWER ALT. CTLR ALLEGEDLY STATES HE DID NOT HEAR THE ERRONEOUS READBACK.
Narrative: WHILE CLBING FROM AN INTERMEDIATE ALT OF FL290 TO FL330, THE CTR CTLR ASKED WHAT ALT WE WERE CLRED TO. WHEN WE RESPONDED 'FL330,' HE ASKED US TO LEVEL OFF AT OUR PRESENT ALT AND WE LEVELED OFF AT FL325. AFTER ABOUT 30 SECONDS, HE STATED THAT HE HAD CLRED US TO FL310 AND MAY HAVE MISSED OUR READBACK OF 'FL330.' HE RECLRED US TO FL310, AND WE DSNDED TO FL310. BOTH OF US ON THE FLT DECK HAD UNDERSTOOD OUR CLRNC TO BE FL330 AND I HAD SET FL330 IN THE ALT ALERT PANEL, SINCE I WAS FLYING, USING THE AUTOFLT SYS. WE DO NOT KNOW IF WE MISHEARD THE CLRNC OR THE CTLR MISTAKENLY CLRED US TO THE WRONG ALT. THERE WAS NO APPARENT TFC CONFLICT. SUPPLEMENTAL INFO FROM ACN 375500: ZAU CLRED US TO FL330. THIS SEEMED ODD, FO READ BACK FL330, CAPT SET FL330 IN MCP AFTER VERBALIZING CLRNC. AT APPROX FL321 ZAU ASKED WHAT ALT WE WERE CLRED TO, WE SAID FL330. CTR SAID STOP CLB AT FL320, THEN RECLRED US BACK TO FL310. CTR SAID HE MISSED THE READBACK.
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.