LNAV disconnect during STAR.

Attributes
ACN	548471
Time
Date	200205
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	intersection : napse
State Reference	NV
Altitude	msl single value : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : l30.tracon
Operator	common carrier : air carrier
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Route In Use	arrival star : kasino 1
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	controller military : 2 flight time last 90 days : 160 flight time total : 7000 flight time type : 700
ASRS Report	548471
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended or assigned course
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

During the final phase of the standard arrival procedure (kasino 1), aircraft had an LNAV disconnect over the napse intersection. Crew immediately turned using heading select to the west to rejoin the arrival. The turn from napse (209 degrees) to whsky (257 degrees) while descending and slowing is probably too much for the LNAV to handle. The visual approach clearance should be given prior to the napse intersection.

Original NASA ASRS Text

Title: LNAV DISCONNECT DURING STAR.

Narrative: DURING THE FINAL PHASE OF THE STANDARD ARR PROC (KASINO 1), ACFT HAD AN LNAV DISCONNECT OVER THE NAPSE INTXN. CREW IMMEDIATELY TURNED USING HEADING SELECT TO THE W TO REJOIN THE ARR. THE TURN FROM NAPSE (209 DEGS) TO WHSKY (257 DEGS) WHILE DSNDING AND SLOWING IS PROBABLY TOO MUCH FOR THE LNAV TO HANDLE. THE VISUAL APCH CLRNC SHOULD BE GIVEN PRIOR TO THE NAPSE INTXN.

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.