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An medium large transport air carrier misunderstood their descent clearance and descended through the altitude of another aircraft.
| Attributes | |
| ACN | 214637 |
| Time | |
| Date | 199207 |
| Day | Wed |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : crp |
| State Reference | TX |
| Altitude | msl bound lower : 24000 msl bound upper : 28000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zhu artcc : zlc |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other Other |
| Flight Phase | cruise other descent other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 250 flight time total : 14000 flight time type : 3000 |
| ASRS Report | 214637 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : undershoot non adherence : clearance other anomaly other |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
While en route iah-crp approximately 70 northeast of crp at 28000, we were first issued clearance to 24000. Moments before beginning the descent we were issued an amended clearance that myself, the captain, and a company check airman in the jump seat understood to be 'descend to 24000 pilot discretion after 26000.' as we were descending through about 25500 center issued us immediate turn to 240 degrees and descend to 24000. At that time, we saw on our TCASII traffic at approximately 11 O'clock and 10 to 12 mi at 25000. We were not being issued either a TA or RA by the TCASII. I feel this occurrence took place due to a misunderstanding of controller's instruction by us, and his subsequent failure to catch our readback of a clearance to 24000 at our discretion after descending to 26000. This was the first flight of the day and all 3 pilots in the cockpit were attentive and diligent during this situation.
Original NASA ASRS Text
Title: AN MLG ACR MISUNDERSTOOD THEIR DSCNT CLRNC AND DSNDED THROUGH THE ALT OF ANOTHER ACFT.
Narrative: WHILE ENRTE IAH-CRP APPROX 70 NE OF CRP AT 28000, WE WERE FIRST ISSUED CLRNC TO 24000. MOMENTS BEFORE BEGINNING THE DSCNT WE WERE ISSUED AN AMENDED CLRNC THAT MYSELF, THE CAPT, AND A COMPANY CHK AIRMAN IN THE JUMP SEAT UNDERSTOOD TO BE 'DSND TO 24000 PLT DISCRETION AFTER 26000.' AS WE WERE DSNDING THROUGH ABOUT 25500 CTR ISSUED US IMMEDIATE TURN TO 240 DEGS AND DSND TO 24000. AT THAT TIME, WE SAW ON OUR TCASII TFC AT APPROX 11 O'CLOCK AND 10 TO 12 MI AT 25000. WE WERE NOT BEING ISSUED EITHER A TA OR RA BY THE TCASII. I FEEL THIS OCCURRENCE TOOK PLACE DUE TO A MISUNDERSTANDING OF CTLR'S INSTRUCTION BY US, AND HIS SUBSEQUENT FAILURE TO CATCH OUR READBACK OF A CLRNC TO 24000 AT OUR DISCRETION AFTER DSNDING TO 26000. THIS WAS THE FIRST FLT OF THE DAY AND ALL 3 PLTS IN THE COCKPIT WERE ATTENTIVE AND DILIGENT DURING THIS SITUATION.
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.