Improperly set flight guidance system led to minor overshoot of altitude during descent.

Attributes
ACN	439570
Time
Date	199906
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : sea.vortac
State Reference	WA
Altitude	msl bound lower : 6900 msl bound upper : 7000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : s46.tracon
Operator	common carrier : air carrier
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : commercial pilot : instrument pilot : cfi
Experience	flight time last 90 days : 100 flight time total : 3400 flight time type : 100
ASRS Report	439576
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to original clearance
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Aircraft was descending with autoplt engaged. Flight guidance computer inadvertently was not programmed with an 'altitude select' mode armed. Of course, at the moment of altitude interception, I was distraction and missed seeing the autoplt not capturing the altitude. Recovery was begun 100 ft below altitude by disengaging autoplt. I will be double- and triplechking 'altitude select' mode on climbs and dscnts. Also, flight automation is still relatively new to me, so I am still developing good habits.

Original NASA ASRS Text

Title: IMPROPERLY SET FLT GUIDANCE SYS LED TO MINOR OVERSHOOT OF ALT DURING DSCNT.

Narrative: ACFT WAS DSNDING WITH AUTOPLT ENGAGED. FLT GUIDANCE COMPUTER INADVERTENTLY WAS NOT PROGRAMMED WITH AN 'ALT SELECT' MODE ARMED. OF COURSE, AT THE MOMENT OF ALT INTERCEPTION, I WAS DISTR AND MISSED SEEING THE AUTOPLT NOT CAPTURING THE ALT. RECOVERY WAS BEGUN 100 FT BELOW ALT BY DISENGAGING AUTOPLT. I WILL BE DOUBLE- AND TRIPLECHKING 'ALT SELECT' MODE ON CLBS AND DSCNTS. ALSO, FLT AUTOMATION IS STILL RELATIVELY NEW TO ME, SO I AM STILL DEVELOPING GOOD HABITS.

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.