A B767 crew, descending into sea, overshot a STAR crossing restr.

Attributes
ACN	535990
Time
Date	200201
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : sea.vortac
State Reference	WA
Altitude	msl single value : 12000
Environment
Flight Conditions	VMC
Weather Elements	Turbulence
Light	Night
Aircraft 1
Controlling Facilities	artcc : zse.artcc tower : iad.tower
Operator	common carrier : air carrier
Make Model Name	B767 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : approach
Route In Use	arrival star : ching 3
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 60 flight time total : 7000 flight time type : 600
ASRS Report	535990
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 750 flight time total : 15000 flight time type : 1500
ASRS Report	535538
Events
Anomaly	altitude deviation : overshoot inflight encounter : weather inflight encounter other non adherence : published procedure non adherence : far non adherence : clearance
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : returned to intended or assigned course
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Descending on chins 3 arrival to sea. Cleared for profile descent for south landing. VNAV descent in use with 12000 ft set in autoplt altitude window. Light to moderate chop encountered at about FL250 and outside of chins intersection. Autoplt mode switched to 'flight level change' in order to slow to turbulence penetration speed of 290 KTS. With autoplt no longer using VNAV restrs from FMS, we descended to and leveled off at 12000 ft near raddy intersection instead of 16000 ft as required by the STAR. No mention of this discrepancy came from ATC. Due to the late hour, apparently there was no conflict with outbound traffic. Recommendations: make certain that the proper altitude is set in altitude window with regards to the mode being used by the autoplt. If the FMS is set properly (as it was in this instance: raddy intersection at 250 KTS, 16000 ft) then a lower altitude may be set in the autoplt altitude window. Once the autoplt is switched to any mode other than VNAV, however, the next required crossing restr must be set in the altitude window. Note: with the use of profile dscnts on stars becoming more prevalent, inadvertent altitude busts due to disconnecting VNAV may occur more often. I recommend more mention of this particular topic during training of flight crew's.

Original NASA ASRS Text

Title: A B767 CREW, DSNDING INTO SEA, OVERSHOT A STAR XING RESTR.

Narrative: DSNDING ON CHINS 3 ARR TO SEA. CLRED FOR PROFILE DSCNT FOR S LNDG. VNAV DSCNT IN USE WITH 12000 FT SET IN AUTOPLT ALT WINDOW. LIGHT TO MODERATE CHOP ENCOUNTERED AT ABOUT FL250 AND OUTSIDE OF CHINS INTXN. AUTOPLT MODE SWITCHED TO 'FLT LEVEL CHANGE' IN ORDER TO SLOW TO TURB PENETRATION SPD OF 290 KTS. WITH AUTOPLT NO LONGER USING VNAV RESTRS FROM FMS, WE DSNDED TO AND LEVELED OFF AT 12000 FT NEAR RADDY INTXN INSTEAD OF 16000 FT AS REQUIRED BY THE STAR. NO MENTION OF THIS DISCREPANCY CAME FROM ATC. DUE TO THE LATE HR, APPARENTLY THERE WAS NO CONFLICT WITH OUTBOUND TFC. RECOMMENDATIONS: MAKE CERTAIN THAT THE PROPER ALT IS SET IN ALT WINDOW WITH REGARDS TO THE MODE BEING USED BY THE AUTOPLT. IF THE FMS IS SET PROPERLY (AS IT WAS IN THIS INSTANCE: RADDY INTXN AT 250 KTS, 16000 FT) THEN A LOWER ALT MAY BE SET IN THE AUTOPLT ALT WINDOW. ONCE THE AUTOPLT IS SWITCHED TO ANY MODE OTHER THAN VNAV, HOWEVER, THE NEXT REQUIRED XING RESTR MUST BE SET IN THE ALT WINDOW. NOTE: WITH THE USE OF PROFILE DSCNTS ON STARS BECOMING MORE PREVALENT, INADVERTENT ALT BUSTS DUE TO DISCONNECTING VNAV MAY OCCUR MORE OFTEN. I RECOMMEND MORE MENTION OF THIS PARTICULAR TOPIC DURING TRAINING OF FLC'S.

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.