CL65 crew set autoplt for a coupled approach when the aircraft could capture a false GS.

Attributes
ACN	515608
Time
Date	200106
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bfl.airport
State Reference	CA
Altitude	msl single value : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bfl.tracon
Operator	common carrier : air carrier
Make Model Name	Regional Jet CL65, Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 30r other
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : multi engine pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 94 flight time total : 4000 flight time type : 986
ASRS Report	515608
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	non adherence : company policies non adherence : published procedure other anomaly other anomaly other
Independent Detector	other flight crewa other flight crewb other other : 3
Resolutory Action	flight crew : overcame equipment problem flight crew : became reoriented
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance FAA
Primary Problem	Flight Crew Human Performance

Narrative:

It's difficult to get ZLA to give us a lower altitude (phx to bfl) until we're nearly over the field. Steep dscnts for the visual approach are common. On this flight the autoplt intercepted a false GS indication and caused the stick to vacillate and release the autoplt. The FAA observe in the jump set thought we had stalled the plane. Is there a way to identify and chart the location of false GS's? Just to add, there was no upset, no injury, and no aircraft damage. However, others have indicated different occasional outcomes.

Original NASA ASRS Text

Title: CL65 CREW SET AUTOPLT FOR A COUPLED APCH WHEN THE ACFT COULD CAPTURE A FALSE GS.

Narrative: IT'S DIFFICULT TO GET ZLA TO GIVE US A LOWER ALT (PHX TO BFL) UNTIL WE'RE NEARLY OVER THE FIELD. STEEP DSCNTS FOR THE VISUAL APCH ARE COMMON. ON THIS FLT THE AUTOPLT INTERCEPTED A FALSE GS INDICATION AND CAUSED THE STICK TO VACILLATE AND RELEASE THE AUTOPLT. THE FAA OBSERVE IN THE JUMP SET THOUGHT WE HAD STALLED THE PLANE. IS THERE A WAY TO IDENT AND CHART THE LOCATION OF FALSE GS'S? JUST TO ADD, THERE WAS NO UPSET, NO INJURY, AND NO ACFT DAMAGE. HOWEVER, OTHERS HAVE INDICATED DIFFERENT OCCASIONAL OUTCOMES.

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.