 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Air carrier X unauthorized descent from assigned altitude had less than standard separation with aircraft at 4000 ft.
| Attributes | |
| ACN | 298120 |
| Time | |
| Date | 199503 |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : azo |
| State Reference | MI |
| Altitude | msl bound lower : 4000 msl bound upper : 4700 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : azo tower : z41 |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : approach descent other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Operating Under FAR Part | other : unknown |
| Flight Phase | cruise other |
| Route In Use | enroute : direct |
| Flight Plan | None |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 46 flight time total : 10000 flight time type : 800 |
| ASRS Report | 298120 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 6000 flight time type : 2000 |
| ASRS Report | 298121 |
| Events | |
| Anomaly | altitude deviation : overshoot conflict : airborne less severe non adherence : published procedure non adherence : clearance non adherence : required legal separation |
| Independent Detector | other controllera |
| Resolutory Action | flight crew : returned to intended course or assigned course other |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Azo approach then cleared air carrier X to 7000 ft, 290 degree heading, and call the field in sight for visual to runway 17. We requested runway 35 (winds calm) as it was shorter time involved, but were told negative. So we complied with 7000 ft 290 degrees. Approach 5 mi south of btl, we called field in sight. Azo approach then said 'roger, and keep your speed 250 KTS or greater until 10 DME.' that caused some confusion in cockpit but replied '250 or greater till 10 DME.' we both thought we had been cleared visual and started a shallow descent out of 7000 ft. Turned left to a more westerly heading for left base runway 17 at azo. At approximately 4700 ft, azo approach called and said 'cleared to 5000 ft. We both froze, looked at each other, then replied '5000 ft. We thought we were cleared visual?' azo approach said, 'negative climb to 5000 ft and maintain 290 degree heading,' and then azo. Approach said 'didn't you see that traffic go behind you at 4000 ft.' we said 'what traffic, negative!' (this was the first mention of any traffic, let alone any possible conflict, by azo approach). 'We said we had the field in sight and we thought you cleared us for the visual.' azo approach then replied, negative, I never cleared you for the visual. You may have had btl in sight but you didn't have azo in sight.' (the visibility was reported on ATIS as 15 mi, but it was at least 25-30 mi at our altitude.) azo approach control then said 'you'd better call tower when you land and talk to the supervisor. Contributing: short flight cockpit workload was extremely buy (control of primary VHF communication radio constantly passed back and forth) pre-occupation on use of non-standard clrncs (ie, 250 KTS or greater below 10000 ft MSL.) complacency on part of pilots hearing only what we think we want to hear. Supplemental information from acn 298121: we were told to report the airport in sight for a visual approach. We replied 'airport in sight.' the approach controller responded and said 'maintain 250 KTS or greater until 10 DME.' TCASII MEL: had TCASII not been deferred, we would have had a heads up on this traffic. Possible complacency on part of controller and pilots. Great WX. Not too busy airport. The problem was discovered when approach control issued us a clearance to 5000 ft. At that point we were at 4700 ft, 2300 ft below our last assigned altitude.
Original NASA ASRS Text
Title: ACR X UNAUTH DSCNT FROM ASSIGNED ALT HAD LTSS WITH ACFT AT 4000 FT.
Narrative: AZO APCH THEN CLRED ACR X TO 7000 FT, 290 DEG HDG, AND CALL THE FIELD IN SIGHT FOR VISUAL TO RWY 17. WE REQUESTED RWY 35 (WINDS CALM) AS IT WAS SHORTER TIME INVOLVED, BUT WERE TOLD NEGATIVE. SO WE COMPLIED WITH 7000 FT 290 DEGS. APCH 5 MI S OF BTL, WE CALLED FIELD IN SIGHT. AZO APCH THEN SAID 'ROGER, AND KEEP YOUR SPD 250 KTS OR GREATER UNTIL 10 DME.' THAT CAUSED SOME CONFUSION IN COCKPIT BUT REPLIED '250 OR GREATER TILL 10 DME.' WE BOTH THOUGHT WE HAD BEEN CLRED VISUAL AND STARTED A SHALLOW DSCNT OUT OF 7000 FT. TURNED L TO A MORE WESTERLY HDG FOR L BASE RWY 17 AT AZO. AT APPROX 4700 FT, AZO APCH CALLED AND SAID 'CLRED TO 5000 FT. WE BOTH FROZE, LOOKED AT EACH OTHER, THEN REPLIED '5000 FT. WE THOUGHT WE WERE CLRED VISUAL?' AZO APCH SAID, 'NEGATIVE CLB TO 5000 FT AND MAINTAIN 290 DEG HDG,' AND THEN AZO. APCH SAID 'DIDN'T YOU SEE THAT TFC GO BEHIND YOU AT 4000 FT.' WE SAID 'WHAT TFC, NEGATIVE!' (THIS WAS THE FIRST MENTION OF ANY TFC, LET ALONE ANY POSSIBLE CONFLICT, BY AZO APCH). 'WE SAID WE HAD THE FIELD IN SIGHT AND WE THOUGHT YOU CLRED US FOR THE VISUAL.' AZO APCH THEN REPLIED, NEGATIVE, I NEVER CLRED YOU FOR THE VISUAL. YOU MAY HAVE HAD BTL IN SIGHT BUT YOU DIDN'T HAVE AZO IN SIGHT.' (THE VISIBILITY WAS RPTED ON ATIS AS 15 MI, BUT IT WAS AT LEAST 25-30 MI AT OUR ALT.) AZO APCH CTL THEN SAID 'YOU'D BETTER CALL TWR WHEN YOU LAND AND TALK TO THE SUPVR. CONTRIBUTING: SHORT FLT COCKPIT WORKLOAD WAS EXTREMELY BUY (CTL OF PRIMARY VHF COM RADIO CONSTANTLY PASSED BACK AND FORTH) PRE-OCCUPATION ON USE OF NON-STANDARD CLRNCS (IE, 250 KTS OR GREATER BELOW 10000 FT MSL.) COMPLACENCY ON PART OF PLTS HEARING ONLY WHAT WE THINK WE WANT TO HEAR. SUPPLEMENTAL INFO FROM ACN 298121: WE WERE TOLD TO RPT THE ARPT IN SIGHT FOR A VISUAL APCH. WE REPLIED 'ARPT IN SIGHT.' THE APCH CTLR RESPONDED AND SAID 'MAINTAIN 250 KTS OR GREATER UNTIL 10 DME.' TCASII MEL: HAD TCASII NOT BEEN DEFERRED, WE WOULD HAVE HAD A HEADS UP ON THIS TFC. POSSIBLE COMPLACENCY ON PART OF CTLR AND PLTS. GREAT WX. NOT TOO BUSY ARPT. THE PROB WAS DISCOVERED WHEN APCH CTL ISSUED US A CLRNC TO 5000 FT. AT THAT POINT WE WERE AT 4700 FT, 2300 FT BELOW OUR LAST ASSIGNED ALT.
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.