Flight crew received GPWS warnings while on the localizer DME approach with pull-ups and terrain calls. Aircraft radar altimeter showed 1200 ft at closest point.

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Attributes
ACN	337807
Time
Date	199606
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mry
State Reference	CA
Altitude	msl bound lower : 4200 msl bound upper : 4200
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mry
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 135
Navigation In Use	Other Other
Flight Phase	descent : approach descent other
Route In Use	enroute airway : mry
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 250 flight time total : 12000 flight time type : 1500
ASRS Report	337807
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	other
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

While executing the localizer DME runway 28L into mry, the GPWS went 'crazy' with a couple of 'terrains,' a few 'pull- ups' and then another 20 'terrains.' this occurred just outside of rodne, the FAF, to just inside rodne. Since we were VMC, I continued the approach (I had the terrain in sight!). The radar altimeter showed 1200 ft at closest point. We continued getting 'terrains' even after the RA showed us more than 2500 ft AGL! Needless to say, most of the passenger woke-up on this one! A note should be on approach plates regarding possible GPWS warnings at specific locations along the final approach course. Reno, nv, localizer runway 34L is another example. Callback conversation with reporter revealed the following information: reporter indicated that the GPWS system uses an envelope of speed and rate of descent to project a terrain warning. He stated that he has flown the approach to mry at a slower speed and did not get the terrain warning. Reporter also indicated that a similar situation exists when making approachs to rno and acv.

Original NASA ASRS Text

Title: FLC RECEIVED GPWS WARNINGS WHILE ON THE LOC DME APCH WITH PULL-UPS AND TERRAIN CALLS. ACFT RADAR ALTIMETER SHOWED 1200 FT AT CLOSEST POINT.

Narrative: WHILE EXECUTING THE LOC DME RWY 28L INTO MRY, THE GPWS WENT 'CRAZY' WITH A COUPLE OF 'TERRAINS,' A FEW 'PULL- UPS' AND THEN ANOTHER 20 'TERRAINS.' THIS OCCURRED JUST OUTSIDE OF RODNE, THE FAF, TO JUST INSIDE RODNE. SINCE WE WERE VMC, I CONTINUED THE APCH (I HAD THE TERRAIN IN SIGHT!). THE RADAR ALTIMETER SHOWED 1200 FT AT CLOSEST POINT. WE CONTINUED GETTING 'TERRAINS' EVEN AFTER THE RA SHOWED US MORE THAN 2500 FT AGL! NEEDLESS TO SAY, MOST OF THE PAX WOKE-UP ON THIS ONE! A NOTE SHOULD BE ON APCH PLATES REGARDING POSSIBLE GPWS WARNINGS AT SPECIFIC LOCATIONS ALONG THE FINAL APCH COURSE. RENO, NV, LOC RWY 34L IS ANOTHER EXAMPLE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR INDICATED THAT THE GPWS SYS USES AN ENVELOPE OF SPD AND RATE OF DSCNT TO PROJECT A TERRAIN WARNING. HE STATED THAT HE HAS FLOWN THE APCH TO MRY AT A SLOWER SPD AND DID NOT GET THE TERRAIN WARNING. RPTR ALSO INDICATED THAT A SIMILAR SIT EXISTS WHEN MAKING APCHS TO RNO AND ACV.

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.