Flight crew descent below the GS to capture the GS at the OM causes a pilot deviation.

Attributes
ACN	342996
Time
Date	199608
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : lax
State Reference	CA
Altitude	msl bound lower : 2100 msl bound upper : 2100
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : lax tower : ord
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival other arrival star : star
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 102 flight time total : 9000 flight time type : 350
ASRS Report	342996
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : crossing restriction not met altitude deviation : overshoot non adherence : far non adherence : clearance non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	none taken : unable
Consequence	faa : investigated
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were cleared on the civet 1 arrival into lax. The captain was flying and made all the crossing restrs on the civet 1 arrival. We were given several increases in speed, also several speed reductions. Upon reaching arnes we were cleared for the ILS runway 25L. We were on the GS and I set in the first 2 stepdown fix altitudes. I assumed that since we were on the GS that we did not need to set all the stepdown altitudes. Based on previous approachs staying on the GS will allow you to meet all the crossing altitudes. I questioned the captain as to what altitude he wanted in the altitude alert. He said set 2100 ft, which is the final approach fix altitude. We were again given a series of speed changes and our workload increased. To allow the flight computers to capture the GS the captain decided to descend to 2100 ft and capture, however, this put us below the GS about 1 1/2 dots. We reintercepted before the final approach fix and landed. Once parked at the gate we were told to call the approach controller.

Original NASA ASRS Text

Title: FLC DSCNT BELOW THE GS TO CAPTURE THE GS AT THE OM CAUSES A PLTDEV.

Narrative: WE WERE CLRED ON THE CIVET 1 ARR INTO LAX. THE CAPT WAS FLYING AND MADE ALL THE XING RESTRS ON THE CIVET 1 ARR. WE WERE GIVEN SEVERAL INCREASES IN SPD, ALSO SEVERAL SPD REDUCTIONS. UPON REACHING ARNES WE WERE CLRED FOR THE ILS RWY 25L. WE WERE ON THE GS AND I SET IN THE FIRST 2 STEPDOWN FIX ALTS. I ASSUMED THAT SINCE WE WERE ON THE GS THAT WE DID NOT NEED TO SET ALL THE STEPDOWN ALTS. BASED ON PREVIOUS APCHS STAYING ON THE GS WILL ALLOW YOU TO MEET ALL THE XING ALTS. I QUESTIONED THE CAPT AS TO WHAT ALT HE WANTED IN THE ALT ALERT. HE SAID SET 2100 FT, WHICH IS THE FINAL APCH FIX ALT. WE WERE AGAIN GIVEN A SERIES OF SPD CHANGES AND OUR WORKLOAD INCREASED. TO ALLOW THE FLT COMPUTERS TO CAPTURE THE GS THE CAPT DECIDED TO DSND TO 2100 FT AND CAPTURE, HOWEVER, THIS PUT US BELOW THE GS ABOUT 1 1/2 DOTS. WE REINTERCEPTED BEFORE THE FINAL APCH FIX AND LANDED. ONCE PARKED AT THE GATE WE WERE TOLD TO CALL THE APCH CTLR.

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.