Widebody transport on test flight after maintenance descends very low to test GPWS.

Attributes
ACN	260035
Time
Date	199312
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : pmd
State Reference	CA
Altitude	agl bound lower : 400 agl bound upper : 600
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	tower : pmd
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Flight Phase	descent : approach landing : missed approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 25 flight time total : 15000 flight time type : 700
ASRS Report	260035
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	other anomaly other other spatial deviation
Independent Detector	other controllera other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

Post 'C check' test flight. On last (third) coupled approach to 50 ft and coupled toga go around, initiated sink to verify GPWS 'don 4 sink' mode. Advised tower, as is the usual custom, of our intent, so if they were observing us, an alarm wouldn't be instituted. At approximately 600 ft AGL, eased over and reduced thrust to generate sink, but couldn't get GPWS to activate. Pulled up and tried again successfully. However, by this time, we were approximately 1 mi west of the airport with sand in windscreen but city ahead. Upon successful generation of GPWS warning, pulled up and continued to 12000 ft for return to lax. My concern is an uniformed ground observer reporting occurrence and subsequent investigation. I do not believe I was in violation of any far (but there's always 91.5 (?), careless and reckless). Prior to commencing this maneuver, everyone in crew is pre-briefed, as well as ATC. It may appear nonstandard or unusual, but is planned and well coordinated.

Original NASA ASRS Text

Title: WDB ON TEST FLT AFTER MAINT DSNDS VERY LOW TO TEST GPWS.

Narrative: POST 'C CHK' TEST FLT. ON LAST (THIRD) COUPLED APCH TO 50 FT AND COUPLED TOGA GAR, INITIATED SINK TO VERIFY GPWS 'DON 4 SINK' MODE. ADVISED TWR, AS IS THE USUAL CUSTOM, OF OUR INTENT, SO IF THEY WERE OBSERVING US, AN ALARM WOULDN'T BE INSTITUTED. AT APPROX 600 FT AGL, EASED OVER AND REDUCED THRUST TO GENERATE SINK, BUT COULDN'T GET GPWS TO ACTIVATE. PULLED UP AND TRIED AGAIN SUCCESSFULLY. HOWEVER, BY THIS TIME, WE WERE APPROX 1 MI W OF THE ARPT WITH SAND IN WINDSCREEN BUT CITY AHEAD. UPON SUCCESSFUL GENERATION OF GPWS WARNING, PULLED UP AND CONTINUED TO 12000 FT FOR RETURN TO LAX. MY CONCERN IS AN UNIFORMED GND OBSERVER RPTING OCCURRENCE AND SUBSEQUENT INVESTIGATION. I DO NOT BELIEVE I WAS IN VIOLATION OF ANY FAR (BUT THERE'S ALWAYS 91.5 (?), CARELESS AND RECKLESS). PRIOR TO COMMENCING THIS MANEUVER, EVERYONE IN CREW IS PRE-BRIEFED, AS WELL AS ATC. IT MAY APPEAR NONSTANDARD OR UNUSUAL, BUT IS PLANNED AND WELL COORDINATED.

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.