 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Flight crew of a lear jet, LR25, descended below assigned altitude according to ATC controller who intervened and then revised their clearance to the lower altitude to which they were descending. Both crew members understood the altitude as to their acknowledgement to ATC. However, if it was wrong, ATC did not advise otherwise.
| Attributes | |
| ACN | 368210 |
| Time | |
| Date | 199705 |
| Day | Thu |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : vuz |
| State Reference | AL |
| Altitude | msl bound lower : 26300 msl bound upper : 27000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : ztl |
| Operator | common carrier : air taxi |
| Make Model Name | Learjet 25 |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air taxi |
| Function | flight crew : captain oversight : pic |
| Qualification | other other : other pilot : atp |
| Experience | flight time last 90 days : 60 flight time total : 6000 flight time type : 2500 |
| ASRS Report | 368210 |
| Person 2 | |
| Affiliation | company : air taxi |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : commercial |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Ambiguous |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We were descending to FL290 when 1 controller handed us off to the ZTL controller where the occurrence happened. We checked on (I, the PIC was flying) and we heard him acknowledge us and give us a clearance to FL260. The first officer read back the clearance to FL260. At FL275 the controller issued a clearance of direct to destination once at FL270. The first officer read back direct to destination 'out of' FL270 (as we heard the original clearance was to FL260). We were just passing FL263 for FL260 when the controller said we were supposed to have maintained FL270, but to now maintain FL260. He then reiterated maintain FL260 and issued an air carrier flight a clearance to maintain FL250. I am not sure if the clrncs were limited but am just assuming so. While passing FL270 we had noticed a B727 pass off our nose from left to right at about a perpendicular flight path. I could not tell what airline the B727 was as it was well below us. From what I could see, no evasive action was taken by any aircraft due to this occurrence. The frequency was fairly busy and judging by the controller's voice he had a lot to handle. Because of this he may have issued us an altitude other than what he intended. Or he may not have heard a possibly incorrect readback on our part. Both my first officer and I heard FL260 as a clearance and so neither of us questioned the clearance.
Original NASA ASRS Text
Title: FLC OF A LEAR JET, LR25, DSNDED BELOW ASSIGNED ALT ACCORDING TO ATC CTLR WHO INTERVENED AND THEN REVISED THEIR CLRNC TO THE LOWER ALT TO WHICH THEY WERE DSNDING. BOTH CREW MEMBERS UNDERSTOOD THE ALT AS TO THEIR ACKNOWLEDGEMENT TO ATC. HOWEVER, IF IT WAS WRONG, ATC DID NOT ADVISE OTHERWISE.
Narrative: WE WERE DSNDING TO FL290 WHEN 1 CTLR HANDED US OFF TO THE ZTL CTLR WHERE THE OCCURRENCE HAPPENED. WE CHKED ON (I, THE PIC WAS FLYING) AND WE HEARD HIM ACKNOWLEDGE US AND GIVE US A CLRNC TO FL260. THE FO READ BACK THE CLRNC TO FL260. AT FL275 THE CTLR ISSUED A CLRNC OF DIRECT TO DEST ONCE AT FL270. THE FO READ BACK DIRECT TO DEST 'OUT OF' FL270 (AS WE HEARD THE ORIGINAL CLRNC WAS TO FL260). WE WERE JUST PASSING FL263 FOR FL260 WHEN THE CTLR SAID WE WERE SUPPOSED TO HAVE MAINTAINED FL270, BUT TO NOW MAINTAIN FL260. HE THEN REITERATED MAINTAIN FL260 AND ISSUED AN ACR FLT A CLRNC TO MAINTAIN FL250. I AM NOT SURE IF THE CLRNCS WERE LIMITED BUT AM JUST ASSUMING SO. WHILE PASSING FL270 WE HAD NOTICED A B727 PASS OFF OUR NOSE FROM L TO R AT ABOUT A PERPENDICULAR FLT PATH. I COULD NOT TELL WHAT AIRLINE THE B727 WAS AS IT WAS WELL BELOW US. FROM WHAT I COULD SEE, NO EVASIVE ACTION WAS TAKEN BY ANY ACFT DUE TO THIS OCCURRENCE. THE FREQ WAS FAIRLY BUSY AND JUDGING BY THE CTLR'S VOICE HE HAD A LOT TO HANDLE. BECAUSE OF THIS HE MAY HAVE ISSUED US AN ALT OTHER THAN WHAT HE INTENDED. OR HE MAY NOT HAVE HEARD A POSSIBLY INCORRECT READBACK ON OUR PART. BOTH MY FO AND I HEARD FL260 AS A CLRNC AND SO NEITHER OF US QUESTIONED THE CLRNC.
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.