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Captain of air carrier medium large transport aircraft responding to TCASII RA, resulted in stopping climb, descending briefly and misinterpreting an ATC heading change for an altitude assignment.
| Attributes | |
| ACN | 207011 |
| Time | |
| Date | 199204 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : ord |
| State Reference | IL |
| Altitude | msl bound lower : 16000 msl bound upper : 16300 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | climbout : intermediate altitude |
| Route In Use | enroute airway : zau |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : commercial pilot : flight engineer pilot : instrument |
| Experience | flight time last 90 days : 210 flight time total : 10000 flight time type : 3000 |
| ASRS Report | 207011 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 185 flight time total : 7360 flight time type : 1900 |
| ASRS Report | 206893 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other other spatial deviation |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
During climb out from O'hare, we were given several intermediate level offs and heading changes working our way southwest toward bradford VOR. The frequency was extremely busy with numerous blocked transmissions. As we approached level off at 16000 ft, both the copilot and I heard '(air carrier flight number) 250,' we both understood the clearance to be to FL250 which we read back as 'climbing to FL250.' what seemed almost simultaneously. Center was calling out traffic, TCASII voiced a TA, momentarily followed by a RA. We immediately followed the RA and descended. We called center to advise of RA at the same time center was calling us. We never saw the traffic visually. The center had wanted heading 250 degree not FL250, some causes: due to frequency congestion and heavy momentary cockpit workload, confirmation of clearance wasn't accomplished on either end. Anticipation of a clearance contributed. Blocked transmissions. Heavy controller workload. TCASII allowed us to react faster to a possible conflict and return to the assigned altitude before losing required ATC separation.
Original NASA ASRS Text
Title: CAPT OF ACR MLG ACFT RESPONDING TO TCASII RA, RESULTED IN STOPPING CLB, DSNDING BRIEFLY AND MISINTERPRETING AN ATC HDG CHANGE FOR AN ALT ASSIGNMENT.
Narrative: DURING CLBOUT FROM O'HARE, WE WERE GIVEN SEVERAL INTERMEDIATE LEVEL OFFS AND HDG CHANGES WORKING OUR WAY SW TOWARD BRADFORD VOR. THE FREQ WAS EXTREMELY BUSY WITH NUMEROUS BLOCKED TRANSMISSIONS. AS WE APCHED LEVEL OFF AT 16000 FT, BOTH THE COPLT AND I HEARD '(ACR FLT NUMBER) 250,' WE BOTH UNDERSTOOD THE CLRNC TO BE TO FL250 WHICH WE READ BACK AS 'CLBING TO FL250.' WHAT SEEMED ALMOST SIMULTANEOUSLY. CTR WAS CALLING OUT TFC, TCASII VOICED A TA, MOMENTARILY FOLLOWED BY A RA. WE IMMEDIATELY FOLLOWED THE RA AND DSNDED. WE CALLED CTR TO ADVISE OF RA AT THE SAME TIME CTR WAS CALLING US. WE NEVER SAW THE TFC VISUALLY. THE CTR HAD WANTED HDG 250 DEG NOT FL250, SOME CAUSES: DUE TO FREQ CONGESTION AND HVY MOMENTARY COCKPIT WORKLOAD, CONFIRMATION OF CLRNC WASN'T ACCOMPLISHED ON EITHER END. ANTICIPATION OF A CLRNC CONTRIBUTED. BLOCKED TRANSMISSIONS. HVY CTLR WORKLOAD. TCASII ALLOWED US TO REACT FASTER TO A POSSIBLE CONFLICT AND RETURN TO THE ASSIGNED ALT BEFORE LOSING REQUIRED ATC SEPARATION.
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.