Flight crew begins descent for crossing restr without descent clearance.

Attributes
ACN	440540
Time
Date	199906
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	intersection : isaak
State Reference	NV
Altitude	msl bound lower : 30500 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla.artcc
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	arrival star : nootn 2
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zla.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise : level
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 153 flight time total : 1500 flight time type : 447
ASRS Report	440536
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : flight engineer pilot : atp pilot : multi engine
Experience	flight time last 90 days : 200 flight time total : 9000 flight time type : 727
ASRS Report	440540
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	atc equipment other atc equipment : radar aircraft equipment : tcas
Resolutory Action	controller : issued new clearance flight crew : returned to assigned airspace
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 18000 vertical : 1500
Supplementary
Problem Areas	Flight Crew Human Performance Chart Or Publication ATC Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

At cruise, FL310, center cleared us 'direct to isaak, nootn 2 arrival.' preparing to begin arrival procedures, I gave the radios to the PF (copilot) and left frequency to give passenger briefing. Noticed copilot setting in new altitude, while also talking on radio and initiating descent to 11000 ft (the altitude that was to cross at phigg intersection on the arrival). Returned to center frequency and heard 'air carrier X, you are not cleared to descend, turn left 20 degrees, maintain FL310.' simultaneously, received RA from TCASII to 'climb.' complied with both ATC and TCASII. Advised to call lax for possible pilot deviation. Copilot had initiated descent because he understood that the crossing altitude at phigg was to be complied with per the nootn arrival.

Original NASA ASRS Text

Title: FLC BEGINS DSCNT FOR XING RESTR WITHOUT DSCNT CLRNC.

Narrative: AT CRUISE, FL310, CTR CLRED US 'DIRECT TO ISAAK, NOOTN 2 ARR.' PREPARING TO BEGIN ARR PROCS, I GAVE THE RADIOS TO THE PF (COPLT) AND LEFT FREQ TO GIVE PAX BRIEFING. NOTICED COPLT SETTING IN NEW ALT, WHILE ALSO TALKING ON RADIO AND INITIATING DSCNT TO 11000 FT (THE ALT THAT WAS TO CROSS AT PHIGG INTXN ON THE ARR). RETURNED TO CTR FREQ AND HEARD 'ACR X, YOU ARE NOT CLRED TO DSND, TURN L 20 DEGS, MAINTAIN FL310.' SIMULTANEOUSLY, RECEIVED RA FROM TCASII TO 'CLB.' COMPLIED WITH BOTH ATC AND TCASII. ADVISED TO CALL LAX FOR POSSIBLE PLTDEV. COPLT HAD INITIATED DSCNT BECAUSE HE UNDERSTOOD THAT THE XING ALT AT PHIGG WAS TO BE COMPLIED WITH PER THE NOOTN ARR.

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.