Large transport transport passenger air carrier acknowledges RNAV STAR altitude clearance, but quest...

Attributes
ACN	560435
Time
Date	200209
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : lynsy
State Reference	NV
Altitude	msl single value : 8000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : l30.tracon
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival star : lynsy rnav 1
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : instrument pilot : atp
Experience	flight time last 90 days : 200 flight time total : 11200 flight time type : 300
ASRS Report	560435
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	altitude deviation : crossing restriction not met altitude deviation : overshoot non adherence : clearance non adherence : published procedure non adherence : far
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance FAA Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Inter Facility Coordination Failure Pilot Deviation Intra Facility Coordination Failure
Situations
ATC Facility	procedure or policy : l30.tracon

Narrative:

We had been cleared direct lynsy and instructed to cross lynsy at 12000 ft and 250 KTS. While complying with this instruction, we received a subsequent instruction from las approach to 'descend via the lynsy one, except maintain 8000 ft.' we took this to mean descent via the lateral constraints of the lynsy one to 8000 ft with other crossing restrs deleted. This may in fact have been the controller's intent. We're still not sure. During compliance with our understanding of this instruction, it occurred to me that perhaps the controller meant for us to descend to 8000 ft via the lynsy one (with both lateral and vertical constraints in effect). We slowed our descent. If the second interpretation was in fact desired, we crossed under the published crossing altitudes at lynsy and mirok by several hundred feet. No traffic conflicts and no unsafe terrain crossing heights occurred to the best of our knowledge. I attempted to clarify the situation by phoning the tower after landing. The tower controller informed us that he favored the first interpretation but gave us a number for the radar room. The radar room supervisor said he favored the second interpretation but acknowledged that terminology was currently undergoing some sort of transformation and he was not certain. Callback conversation with reporter revealed the following information: reporter stated that the first officer had already initiated their descent as the captain questioned the clearance intent with the first officer. Reporter was advised of an FAA genot clarifying controller phraseology and STAR clearance intent. Reporter advised that he will be asking for more clarification in the future.

Original NASA ASRS Text

Title: LGT TRANSPORT PAX ACR ACKNOWLEDGES RNAV STAR ALT CLRNC, BUT QUESTIONS INTENT WITH FO AND NOT ATC, RESULTING IN AN ALT XING RESTR OVERSHOOT. CALLS TWR AND TRACON, AND OBTAINS 2 INTERPS OF THE CLRNC.

Narrative: WE HAD BEEN CLRED DIRECT LYNSY AND INSTRUCTED TO CROSS LYNSY AT 12000 FT AND 250 KTS. WHILE COMPLYING WITH THIS INSTRUCTION, WE RECEIVED A SUBSEQUENT INSTRUCTION FROM LAS APCH TO 'DSND VIA THE LYNSY ONE, EXCEPT MAINTAIN 8000 FT.' WE TOOK THIS TO MEAN DSCNT VIA THE LATERAL CONSTRAINTS OF THE LYNSY ONE TO 8000 FT WITH OTHER XING RESTRS DELETED. THIS MAY IN FACT HAVE BEEN THE CTLR'S INTENT. WE'RE STILL NOT SURE. DURING COMPLIANCE WITH OUR UNDERSTANDING OF THIS INSTRUCTION, IT OCCURRED TO ME THAT PERHAPS THE CTLR MEANT FOR US TO DSND TO 8000 FT VIA THE LYNSY ONE (WITH BOTH LATERAL AND VERT CONSTRAINTS IN EFFECT). WE SLOWED OUR DSCNT. IF THE SECOND INTERP WAS IN FACT DESIRED, WE CROSSED UNDER THE PUBLISHED XING ALTS AT LYNSY AND MIROK BY SEVERAL HUNDRED FEET. NO TFC CONFLICTS AND NO UNSAFE TERRAIN XING HEIGHTS OCCURRED TO THE BEST OF OUR KNOWLEDGE. I ATTEMPTED TO CLARIFY THE SIT BY PHONING THE TWR AFTER LNDG. THE TWR CTLR INFORMED US THAT HE FAVORED THE FIRST INTERP BUT GAVE US A NUMBER FOR THE RADAR ROOM. THE RADAR ROOM SUPVR SAID HE FAVORED THE SECOND INTERP BUT ACKNOWLEDGED THAT TERMINOLOGY WAS CURRENTLY UNDERGOING SOME SORT OF TRANSFORMATION AND HE WAS NOT CERTAIN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE FO HAD ALREADY INITIATED THEIR DSCNT AS THE CAPT QUESTIONED THE CLRNC INTENT WITH THE FO. RPTR WAS ADVISED OF AN FAA GENOT CLARIFYING CTLR PHRASEOLOGY AND STAR CLRNC INTENT. RPTR ADVISED THAT HE WILL BE ASKING FOR MORE CLARIFICATION IN THE FUTURE.

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.

Large transport transport passenger air carrier acknowledges RNAV STAR altitude clearance, but questions intent with first officer and not ATC, resulting in an altitude crossing restr overshoot. Calls tower and TRACON, and obtains 2 interps of the clearance.