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Less than standard separation pilot deviation between cpr jet and unknown aircraft while in descent caught up and passed an unknown aircraft at the same altitude. Center controller miscom an inappropriate command to the flight crew to begin descent after the aircraft was already in descent from previous descent clearance to 17000 ft and adding an expect to cross restr of 11000 ft. The cpr jet was non mode C. The flight crew, expecting the crossing restr, descended through 17000 ft without a clearance.
| Attributes | |
| ACN | 365710 |
| Time | |
| Date | 199703 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : las |
| State Reference | NV |
| Altitude | msl bound lower : 13200 msl bound upper : 17000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zla tower : ict |
| Operator | general aviation : corporate |
| Make Model Name | IAI1125 (Astra) |
| Operating Under FAR Part | Part 91 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Route In Use | arrival other arrival star : star |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Operating Under FAR Part | other : unknown |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : first officer |
| Qualification | pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 90 flight time total : 10300 flight time type : 1200 |
| ASRS Report | 365710 |
| Person 2 | |
| Affiliation | Other |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 90 flight time total : 9800 flight time type : 1500 |
| ASRS Report | 365709 |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation non adherence : clearance |
| Independent Detector | other controllera |
| Resolutory Action | none taken : detected after the fact |
| Consequence | faa : reviewed incident with flight crew |
| Miss Distance | horizontal : 2500 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Controller states, 'abc descend to 17000 ft, las altimeter 30.30.' I accept this 17000 ft altitude assignment. (2 things must note: 1) we are operating without mode C, 2) I am listening and relistening to the copy of the ATC tape we got under the foi act, as I write this.) now we are descending from around FL284 to 17000 ft. During this descent I go off frequency to get ATIS. I am just coming back from ATIS when I see the PF descending (or about to descend) through the altitude set on the altitude alerter. I point to the altitude alerter altitude and he confidently waves me off and says that we are to cross crowe intersection at 11000 ft. What I didn't know then, but heard on the tape later, was that as we were descending through about FL200 he heard the controller say 'abc, begin descent and expect to cross crowe at 11000 ft.' this call was not acknowledged because of other immediate xmissions from other aircraft. Then he heard 'abc, start your descent (spoken emphatically) and...uh...we need you to be...expect to cross crow at 11000 ft...expect that.' I just came back on frequency in time to say, 'ok, we are descending and expect crow at 11000 ft.' shortly after this, the deviation occurred. This caused the ATC alarm to sound when we caught up from behind and passed another IFR aircraft within the lateral limits while at his altitude.
Original NASA ASRS Text
Title: LTSS PLTDEV BTWN CPR JET AND UNKNOWN ACFT WHILE IN DSCNT CAUGHT UP AND PASSED AN UNKNOWN ACFT AT THE SAME ALT. CTR CTLR MISCOM AN INAPPROPRIATE COMMAND TO THE FLC TO BEGIN DSCNT AFTER THE ACFT WAS ALREADY IN DSCNT FROM PREVIOUS DSCNT CLRNC TO 17000 FT AND ADDING AN EXPECT TO CROSS RESTR OF 11000 FT. THE CPR JET WAS NON MODE C. THE FLC, EXPECTING THE XING RESTR, DSNDED THROUGH 17000 FT WITHOUT A CLRNC.
Narrative: CTLR STATES, 'ABC DSND TO 17000 FT, LAS ALTIMETER 30.30.' I ACCEPT THIS 17000 FT ALT ASSIGNMENT. (2 THINGS MUST NOTE: 1) WE ARE OPERATING WITHOUT MODE C, 2) I AM LISTENING AND RELISTENING TO THE COPY OF THE ATC TAPE WE GOT UNDER THE FOI ACT, AS I WRITE THIS.) NOW WE ARE DSNDING FROM AROUND FL284 TO 17000 FT. DURING THIS DSCNT I GO OFF FREQ TO GET ATIS. I AM JUST COMING BACK FROM ATIS WHEN I SEE THE PF DSNDING (OR ABOUT TO DSND) THROUGH THE ALT SET ON THE ALT ALERTER. I POINT TO THE ALT ALERTER ALT AND HE CONFIDENTLY WAVES ME OFF AND SAYS THAT WE ARE TO CROSS CROWE INTXN AT 11000 FT. WHAT I DIDN'T KNOW THEN, BUT HEARD ON THE TAPE LATER, WAS THAT AS WE WERE DSNDING THROUGH ABOUT FL200 HE HEARD THE CTLR SAY 'ABC, BEGIN DSCNT AND EXPECT TO CROSS CROWE AT 11000 FT.' THIS CALL WAS NOT ACKNOWLEDGED BECAUSE OF OTHER IMMEDIATE XMISSIONS FROM OTHER ACFT. THEN HE HEARD 'ABC, START YOUR DSCNT (SPOKEN EMPHATICALLY) AND...UH...WE NEED YOU TO BE...EXPECT TO CROSS CROW AT 11000 FT...EXPECT THAT.' I JUST CAME BACK ON FREQ IN TIME TO SAY, 'OK, WE ARE DSNDING AND EXPECT CROW AT 11000 FT.' SHORTLY AFTER THIS, THE DEV OCCURRED. THIS CAUSED THE ATC ALARM TO SOUND WHEN WE CAUGHT UP FROM BEHIND AND PASSED ANOTHER IFR ACFT WITHIN THE LATERAL LIMITS WHILE AT HIS 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.