B757-200 captain reports ambiguity between GS and PAPI on approach to runway 8 at tjsj.

Attributes
ACN	758886
Time
Date	200710
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : tjsj.airport
State Reference	PR
Altitude	msl single value : 1600
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : tjsj.tracon
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 08
Flight Phase	descent : approach
Route In Use	approach : instrument precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	758886
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	aircraft : equipment problem dissipated
Supplementary
Problem Areas	Navigational Facility Aircraft
Primary Problem	Ambiguous

Narrative:

We turned in for runway 8 at tjsj from a north visual turning in over patty. We were at 1600 ft as cleared by the approach controller and finishing the mechanical checklist we had a 2 DOT high indication on the GS. I looked at the runway 8 PAPI and from the angle of the turn in it looked close to being on a normal GS. I told the first officer to start the aircraft down. Now we looked low as we finished the turn and the GS reversed itself. We were now 2 dots low! We corrected to the PAPI then the GS looked now normal. We had a normal approach from that point on. I have seen this at this airport before and nothing has ever been fixed on this approach.

Original NASA ASRS Text

Title: B757-200 CAPTAIN REPORTS AMBIGUITY BETWEEN GS AND PAPI ON APCH TO RWY 8 AT TJSJ.

Narrative: WE TURNED IN FOR RWY 8 AT TJSJ FROM A N VISUAL TURNING IN OVER PATTY. WE WERE AT 1600 FT AS CLRED BY THE APCH CTLR AND FINISHING THE MECHANICAL CHKLIST WE HAD A 2 DOT HIGH INDICATION ON THE GS. I LOOKED AT THE RWY 8 PAPI AND FROM THE ANGLE OF THE TURN IN IT LOOKED CLOSE TO BEING ON A NORMAL GS. I TOLD THE FO TO START THE ACFT DOWN. NOW WE LOOKED LOW AS WE FINISHED THE TURN AND THE GS REVERSED ITSELF. WE WERE NOW 2 DOTS LOW! WE CORRECTED TO THE PAPI THEN THE GS LOOKED NOW NORMAL. WE HAD A NORMAL APCH FROM THAT POINT ON. I HAVE SEEN THIS AT THIS ARPT BEFORE AND NOTHING HAS EVER BEEN FIXED ON THIS APCH.

Data retrieved from NASA's ASRS site as of January 2009 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.