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Late amendment of cleared altitude results in loss of separation between C560 cleared to FL370 and crossing traffic at FL360.
| Attributes | |
| ACN | 718049 |
| Time | |
| Date | 200611 |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | navaid : tay.vortac |
| State Reference | FL |
| Altitude | msl single value : 35300 |
| Environment | |
| Flight Conditions | VMC |
| Light | Dusk |
| Aircraft 1 | |
| Controlling Facilities | artcc : zjx.artcc |
| Operator | general aviation : corporate |
| Make Model Name | Citation Excel |
| Operating Under FAR Part | Part 91 |
| Flight Phase | climbout : intermediate altitude |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zjx.artcc |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Person 1 | |
| Affiliation | company : corporate |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 100 flight time total : 5500 flight time type : 700 |
| ASRS Report | 718049 |
| Person 2 | |
| Affiliation | company : corporate |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 90 flight time total : 5000 flight time type : 250 |
| ASRS Report | 718050 |
| Events | |
| Anomaly | conflict : airborne critical non adherence : required legal separation other anomaly other |
| Independent Detector | aircraft equipment : tcas other controllera |
| Resolutory Action | controller : issued new clearance flight crew : took precautionary avoidance action |
| Supplementary | |
| Problem Areas | ATC Human Performance |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
We were cleared to FL370. Upon passing FL352; center said 'amend altitude; maintain FL350.' PF arrested the climb and began a descent to FL350 when the TCAS gave a TA call. Traffic was at 1:30 O'clock position; and 2 mi. I acquired said target visually and read back 'descending to FL350.' control replied 'verify you're level at 350?' and I explained we were trying; but he had originally cleared us to 370 and only changed it to 350 once we were at FL352. He replied 'roger.' about 2 mins later he asked; 'are you in the turn?' I re-verified everything again; flight level; heading; etc. The controller was noticeably confused; missed radio calls; gave us a bad altitude. Something did not seem right with the controller. Some of his replies; sounded slurred like he may have been overly tired or something.
Original NASA ASRS Text
Title: LATE AMENDMENT OF CLRED ALT RESULTS IN LOSS OF SEPARATION BTWN C560 CLRED TO FL370 AND XING TFC AT FL360.
Narrative: WE WERE CLRED TO FL370. UPON PASSING FL352; CTR SAID 'AMEND ALT; MAINTAIN FL350.' PF ARRESTED THE CLB AND BEGAN A DSCNT TO FL350 WHEN THE TCAS GAVE A TA CALL. TFC WAS AT 1:30 O'CLOCK POS; AND 2 MI. I ACQUIRED SAID TARGET VISUALLY AND READ BACK 'DSNDING TO FL350.' CTL REPLIED 'VERIFY YOU'RE LEVEL AT 350?' AND I EXPLAINED WE WERE TRYING; BUT HE HAD ORIGINALLY CLRED US TO 370 AND ONLY CHANGED IT TO 350 ONCE WE WERE AT FL352. HE REPLIED 'ROGER.' ABOUT 2 MINS LATER HE ASKED; 'ARE YOU IN THE TURN?' I RE-VERIFIED EVERYTHING AGAIN; FLT LEVEL; HDG; ETC. THE CTLR WAS NOTICEABLY CONFUSED; MISSED RADIO CALLS; GAVE US A BAD ALT. SOMETHING DID NOT SEEM RIGHT WITH THE CTLR. SOME OF HIS REPLIES; SOUNDED SLURRED LIKE HE MAY HAVE BEEN OVERLY TIRED OR SOMETHING.
Data retrieved from NASA's ASRS site as of January 2009 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.