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Reports from both the radar and associate controllers describe operational error and operational deviation at FL350 when both failed to hear incorrect altitude readback.
| Attributes | |
| ACN | 672957 |
| Time | |
| Date | 200509 |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | navaid : pxv.vortac |
| State Reference | IN |
| Altitude | msl single value : 35000 |
| Environment | |
| Flight Conditions | IMC IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zid.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | MD-82 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | climbout : vacating altitude climbout : intermediate altitude |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zid.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | EMB ERJ 145 ER&LR |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller non radar : 2 controller radar : 15 |
| ASRS Report | 672957 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : developmental |
| ASRS Report | 674158 |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation |
| Independent Detector | atc equipment : conflict alert aircraft equipment : tcas other controllera other controllerb |
| Resolutory Action | controller : issued new clearance controller : issued alert flight crew : took evasive action |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 7000 vertical : 700 |
| Supplementary | |
| Problem Areas | ATC Human Performance |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Deviation Operational Error |
Narrative:
Air carrier X level at FL330 requesting FL350. Air carrier X was climbed to FL340; the top altitude of the sector. Air carrier X read back FL350; which was missed. Air carrier X was switched to the next frequency but did not go over. Instead; asked about traffic and responded to an RA. Air carrier X was reissued FL340. Separation was lost between air carrier X and air carrier Y who remained level at FL350. Conflict alert activated after loss of separation. Supplemental information from acn 674158: I was working radar associate position. Radar person gave aircraft #1 clearance to climb to FL340. The pilot read back FL350 and neither radar controller nor I caught the readback. I was on the landline at the time of the clearance so I didn't hear it. As air carrier X passed through FL340 (we were showing that he had just leveled); the pilot said; 'we are responding to our TCASII.' the controller told him to verify level at FL340 but the pilot insisted he was assigned FL350. His traffic was at FL350; which belonged to the sector above us so we didn't have a full data block on him. The radar person descended air carrier X back to FL340 but they had already lost separation.
Original NASA ASRS Text
Title: RPTS FROM BOTH THE RADAR AND ASSOCIATE CTLRS DESCRIBE OPERROR AND OPDEV AT FL350 WHEN BOTH FAILED TO HEAR INCORRECT ALT READBACK.
Narrative: ACR X LEVEL AT FL330 REQUESTING FL350. ACR X WAS CLBED TO FL340; THE TOP ALT OF THE SECTOR. ACR X READ BACK FL350; WHICH WAS MISSED. ACR X WAS SWITCHED TO THE NEXT FREQ BUT DID NOT GO OVER. INSTEAD; ASKED ABOUT TFC AND RESPONDED TO AN RA. ACR X WAS REISSUED FL340. SEPARATION WAS LOST BTWN ACR X AND ACR Y WHO REMAINED LEVEL AT FL350. CONFLICT ALERT ACTIVATED AFTER LOSS OF SEPARATION. SUPPLEMENTAL INFO FROM ACN 674158: I WAS WORKING RADAR ASSOCIATE POS. RADAR PERSON GAVE ACFT #1 CLRNC TO CLB TO FL340. THE PLT READ BACK FL350 AND NEITHER RADAR CTLR NOR I CAUGHT THE READBACK. I WAS ON THE LANDLINE AT THE TIME OF THE CLRNC SO I DIDN'T HEAR IT. AS ACR X PASSED THROUGH FL340 (WE WERE SHOWING THAT HE HAD JUST LEVELED); THE PLT SAID; 'WE ARE RESPONDING TO OUR TCASII.' THE CTLR TOLD HIM TO VERIFY LEVEL AT FL340 BUT THE PLT INSISTED HE WAS ASSIGNED FL350. HIS TFC WAS AT FL350; WHICH BELONGED TO THE SECTOR ABOVE US SO WE DIDN'T HAVE A FULL DATA BLOCK ON HIM. THE RADAR PERSON DSNDED ACR X BACK TO FL340 BUT THEY HAD ALREADY LOST SEPARATION.
Data retrieved from NASA's ASRS site as of January 2009 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.