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Less than standard separation 3 air carrier aircraft at FL310, FL330 and FL350 climbing and descending as cleared by ZOA.
| Attributes | |
| ACN | 160702 |
| Time | |
| Date | 199010 |
| Day | Sun |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : fra |
| State Reference | CA |
| Altitude | msl bound lower : 31000 msl bound upper : 33000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Dusk |
| Aircraft 1 | |
| Controlling Facilities | artcc : zoa |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other |
| Flight Phase | climbout : intermediate altitude cruise other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : instrument pilot : flight engineer pilot : commercial pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 190 flight time total : 8000 flight time type : 800 |
| ASRS Report | 160702 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 180 flight time total : 5330 flight time type : 1310 |
| ASRS Report | 160402 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance non adherence : required legal separation other anomaly other |
| Independent Detector | other controllera other flight crewa |
| Resolutory Action | controller : issued new clearance other |
| Consequence | Other |
| Miss Distance | horizontal : 24000 vertical : 2000 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Pilot Deviation Operational Error |
Narrative:
We were cleared to FL310. After leveling off, ZOA called and said to increase our rate of climb. We immediately replied we were cleared to FL310. Center came back and said, 'I cleared you up to 330--climb immediately.' we climbed. He gave an air carrier Y flight directions to increase their rate of descent and a turn, then a turn for us to increase sep. After getting sep established the controller came back rather heatedly saying, 'I gave you clearance to FL330 and somebody in that cockpit acknowledged it.' he said he had not received or acknowledged such a clearance. A few seconds later an air carrier Z came on the radio and said 'we descended from 350 to 330--do you want us to go back up to 350?' it seems that either center used air carrier Z's call sign for the FL330 clearance or they used ours, but we didn't hear it while air carrier Z thought it was for them and acknowledged. It all created a potential collision due to readback/hearback problem. Center expected us to acknowledge the clearance and evidently heard air carrier Z, thinking it was us.
Original NASA ASRS Text
Title: LESS THAN STANDARD SEPARATION 3 ACR ACFT AT FL310, FL330 AND FL350 CLIMBING AND DESCENDING AS CLEARED BY ZOA.
Narrative: WE WERE CLRED TO FL310. AFTER LEVELING OFF, ZOA CALLED AND SAID TO INCREASE OUR RATE OF CLB. WE IMMEDIATELY REPLIED WE WERE CLRED TO FL310. CENTER CAME BACK AND SAID, 'I CLRED YOU UP TO 330--CLB IMMEDIATELY.' WE CLBED. HE GAVE AN ACR Y FLT DIRECTIONS TO INCREASE THEIR RATE OF DSNT AND A TURN, THEN A TURN FOR US TO INCREASE SEP. AFTER GETTING SEP ESTABLISHED THE CTLR CAME BACK RATHER HEATEDLY SAYING, 'I GAVE YOU CLRNC TO FL330 AND SOMEBODY IN THAT COCKPIT ACKNOWLEDGED IT.' HE SAID HE HAD NOT RECEIVED OR ACKNOWLEDGED SUCH A CLRNC. A FEW SECS LATER AN ACR Z CAME ON THE RADIO AND SAID 'WE DSNDED FROM 350 TO 330--DO YOU WANT US TO GO BACK UP TO 350?' IT SEEMS THAT EITHER CENTER USED ACR Z'S CALL SIGN FOR THE FL330 CLRNC OR THEY USED OURS, BUT WE DIDN'T HEAR IT WHILE ACR Z THOUGHT IT WAS FOR THEM AND ACKNOWLEDGED. IT ALL CREATED A POTENTIAL COLLISION DUE TO READBACK/HEARBACK PROB. CENTER EXPECTED US TO ACKNOWLEDGE THE CLRNC AND EVIDENTLY HEARD ACR Z, THINKING IT WAS US.
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.