AN MD11 DSNDING INTO HKG RECEIVES A TERRAIN WARNING FROM THE GPWS. FLC EXECUTES AN ESCAPE MANEUVER TO SILENCE THE WARNING.

Narrative

OPERATING SEL-HKG NIGHT IMC XX38 LCL TIME; FO FLYING. APCHING AKERO; WE WERE CLRED DIRECT TD FOR RWY 25L. SHORTLY THEREAFTER; WE WERE TOLD OF A RWY CHANGE TO RWY 7R AND WERE CLRED DIRECT TO SOKOE INTXN; EXPECT VECTORS FOR RWY 7R; DSND TO 3000 FT. APPROX 10 MI FROM SOKOE; WE WERE CLRED FOR ILS PROC RWY 7R. WE WERE COMING IN TO SOKOE FROM THE S ON A DIRECT ROUTING HDG APPROX 330 DEGS. THIS CALLED FOR A L TURN TO INTERCEPT THE BASE LEG OF THE PROC INSTEAD OF A R-HAND TURN AS DEPICTED. AFTER XING SOKOE AT 3000 FT WE TURNED L TO JOIN BASE LEG. ROLLING OUT ONTO BASE COURSE; WE STARTED A DSCNT FROM 3000 FT TO 2000 FT AS DEPICTED. AT APPROX 2300 FT; WE HEARD THE TERRAIN WARNING FROM GPWS. FO IMMEDIATELY INITIATED ESCAPE MANEUVER AND WE STARTED TO CLB. AT THE SAME TIME APCH GAVE US AN IMMEDIATE TURN TO 300 DEGS DUE TO TERRAIN WHICH WE COMPLIED WITH. AFTER THE INITIAL TERRAIN WARNING; THE GPWS WAS SILENT SO WE LEVELED AT 3000 FT AND INFORMED APCH WE WERE LEVEL 3000 FT HDG 300 DEGS. WE WERE THEN CLRED TO 2000 FT AND VECTORED FOR APCH. UP TO THE POINT OF THE ESCAPE MANEUVER; ACFT WAS ON AUTOPLT IN NAV WITH ALL SYS WORKING. ALTIMETER WAS SET CORRECTLY. IT WOULD SEEM THAT COMING INTO SOKOE HDG N AND PICKING UP THE PROC FROM THAT POINT PUTS YOU CLOSER TO SEVERAL SMALL ISLANDS THAN YOU WOULD BE COMING FROM TD AND MAKING THE R TURN TO BASE SEGMENT. ALSO; I CAN'T REMEMBER IF WE HAD PASSED LIMES INTXN PRIOR TO LEAVING 3000 FT FOR 2000 FT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT AS THEY WERE DSNDING FROM 3000 FT ALT; AT 2300 FT; THE GPWS SOUNDED WITH THE WARNING; 'TERRAIN; TERRAIN; TERRAIN.' THEY EXECUTED AN ESCAPE MANEUVER AS TRAINED; CLBING TO 3000 FT. TRACON SAW THE CLB AND TOLD THEM IT WAS STILL PROPER FOR THEM TO DSND. TRACON OFFERED NO REASON WHY THEY SHOULD GET A GPWS WARNING. AFTER TAKING EVASIVE ACTION; THE FLC DSNDED THE ACFT BACK DOWN TO TFC PATTERN ALT; FOLLOWED THE VECTOR FROM TRACON TO PUT THEM IN A NORMAL TFC SEQUENCE. AFTER LNDG AT HKG; THE FLC HAD WRITTEN IT UP IN THE LOGBOOK. THE TAPE OF THE RADAR ALTIMETER WAS READ AND IT SHOWED THE AGL ALT CHANGE FROM 2300 FT TO 1560 FT. THIS HAPPENED OVER A SHORT PERIOD OF TIME WHICH CAUSED THE GPWS TO SOUND. SUPPLEMENTAL INFO FROM ACN 417048: APCH CTL ISSUED A TURN TO 300 DEGS DUE TO HIGH TERRAIN IN THE VICINITY; WHICH WE COMPLIED WITH. WITH THE GPWS SILENT AT 3000 FT (ALSO MSA FOR OUR QUADRANT); WE LEVELED AT 3000 FT AND INFORMED APCH CTL WE WERE LEVEL AT 3000 FT; HDG 300 DEGS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THEY HAD DSNDED ALL THE WAY TO 2300 FT; WHEN THE RADAR ALTIMETER STARTED TO SHOW AN ALT OF 1750 FT. SUDDENLY THE RADAR ALT CHANGED 200 FT. THIS WAS WHEN THE GPWS SOUNDED. THE TERRAIN WARNING ONLY SOUNDED TWICE. BY THEN; THEY HAD STARTED THE ESCAPE MANEUVER AND THE TERRAIN WARNING QUIT. THE GPWS WAS A VERY SHORT EVENT.