|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1201 To 1800|
|Locale Reference||atc facility : nuw|
|Altitude||msl bound lower : 10000|
msl bound upper : 11000
|Controlling Facilities||artcc : zse|
|Operator||general aviation : personal|
|Make Model Name||Small Transport, Low Wing, 2 Recip Eng|
|Flight Phase||cruise other|
|Route In Use||enroute : direct|
|Make Model Name||Fighter|
|Flight Phase||descent other|
|Affiliation||government : faa|
|Function||controller : radar|
|Qualification||controller : radar|
|Function||flight crew : single pilot|
|Qualification||pilot : instrument|
|Anomaly||non adherence : published procedure|
non adherence : required legal separation
other anomaly other
|Independent Detector||atc equipment other atc equipment : unspecified|
|Resolutory Action||none taken : insufficient time|
|Consequence||faa : investigated|
|Miss Distance||horizontal : 1500|
vertical : 0
|Primary Problem||ATC Human Performance|
|Air Traffic Incident||Operational Error|
I was working ZSE ARTCC sector R3. This sector is seattle north to the canadian boundary. I was providing instruction to an r-side trnee. An small transport was northbound to yyj at 10000'. 2 fgts called for clearance to nuw from olympic MOA. The fgts were cleared direct to nuw at FL230. There were other flts of fgts returning from the east. Much sequencing was involved. Icing was involved in other aircraft at the same time. The fgts were given 11000' for descent to nuw. Crossing traffic was the small transport at 10000'. After leveling at 11000', the fgts requested lower because of ice. My trnee was slow in reacting, so I started to take over the sector. My first transmission was to the fgts with 'traffic 2 O'clock, 3 mi, nwbnd at 10000', expect lower when clear.' the pilot read back, 'roger, descending to 10000'.' I missed the readback. Loss of sep happened almost immediately. The targets merged. I asked the altitude of the fgts and they said level at 10000' assigned. Recommendations: I believe the pilot had lower altitude in his mind. It didn't matter what I said, I think he was going to do what he wanted to.
Original NASA ASRS Text
Title: ACFT DESCENDED TO AN ALT ASSIGNED TO ANOTHER ACFT.
Narrative: I WAS WORKING ZSE ARTCC SECTOR R3. THIS SECTOR IS SEATTLE N TO THE CANADIAN BOUNDARY. I WAS PROVIDING INSTRUCTION TO AN R-SIDE TRNEE. AN SMT WAS NBOUND TO YYJ AT 10000'. 2 FGTS CALLED FOR CLRNC TO NUW FROM OLYMPIC MOA. THE FGTS WERE CLRED DIRECT TO NUW AT FL230. THERE WERE OTHER FLTS OF FGTS RETURNING FROM THE E. MUCH SEQUENCING WAS INVOLVED. ICING WAS INVOLVED IN OTHER ACFT AT THE SAME TIME. THE FGTS WERE GIVEN 11000' FOR DSCNT TO NUW. XING TFC WAS THE SMT AT 10000'. AFTER LEVELING AT 11000', THE FGTS REQUESTED LOWER BECAUSE OF ICE. MY TRNEE WAS SLOW IN REACTING, SO I STARTED TO TAKE OVER THE SECTOR. MY FIRST XMISSION WAS TO THE FGTS WITH 'TFC 2 O'CLOCK, 3 MI, NWBND AT 10000', EXPECT LOWER WHEN CLR.' THE PLT READ BACK, 'ROGER, DSNDING TO 10000'.' I MISSED THE READBACK. LOSS OF SEP HAPPENED ALMOST IMMEDIATELY. THE TARGETS MERGED. I ASKED THE ALT OF THE FGTS AND THEY SAID LEVEL AT 10000' ASSIGNED. RECOMMENDATIONS: I BELIEVE THE PLT HAD LOWER ALT IN HIS MIND. IT DIDN'T MATTER WHAT I SAID, I THINK HE WAS GOING TO DO WHAT HE WANTED TO.
Data retrieved from NASA's ASRS site as of August 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.