A B727 CAPT; LACKING RECENT EXPERIENCE; DEMONSTRATED DIFFICULTY IN KEEPING UP WITH THE ACFT; CULMINATING IN A GPWS WARNING WHEN DSNDING BELOW THE GS DURING AN ILS APCH.

Narrative

THE PIC SEEMED TO HAVE DIFFICULTY OPERATING THE ACFT ON DEP FROM MEM BECAUSE HE WAS NOT FOLLOWING STANDARD PROCS. HE DID NOT OPERATE UNSAFELY; ONLY NONSTANDARD. I MADE A MENTAL NOTE TO PAY EXTREME ATTN DURING THE REMAINDER OF THE FLT. HE BEGAN DSCNT FROM FL240 AT 55 DME. FOR TFC SEPARATION; WE WERE VECTORED ACROSS THE LOC TO INTERCEPT A 340 DEG HDG FOR ILS 1. APCH CLRNC WAS TO MAINTAIN 2500 FT TILL ESTABLISHED ON LOC; CLRED ILS RWY 1 APCH. AT 10 DME AND 210 KTS; I PROMPTED FOR FLAPS AND/OR GEAR. WE IMMEDIATELY BEGAN TO CONFIGURE. THE AUTOPLT INTERCEPTED THE LOC. THE GS CAME ALIVE AND I MADE THE CALL 'GS ALIVE.' WE CONTINUED WITH CONFIGURING THE ACFT AND THE AUTOPLT SEEMED TO BE TRACKING CORRECTLY. I CONTINUED MY PNF DUTIES; CHKING IN WITH TWR; RUNNING CHKLISTS; CONFIGURING THE ACFT. ON XCHKING INSTRUMENTATION; I FOUND WE WERE FULL SCALE DEFLECTION; LOW ON THE GS AT 1600 FT MSL. WE IMMEDIATELY BROKE OUT AND I SAW RED/RED PAPI AND COMMANDED 'CHK GS; YOU'RE FULL SCALE LOW; FLY THE VASI; STOP DSCNT.' SOME RELUCTANCE FROM THE PIC ABOUT THIS PROMPTED ME TO REPEAT 'YOU'RE LOW; FLY UP TO THE PAPI; YOU'RE STILL RED OVER RED!' WHEREUPON HE FINALLY DID. THE GPWS THEN WENT OFF 'GS; GS.' BY 1000 FT AGL; THE ACFT WAS STABILIZED AS REQUIRED AND WE LANDED. ON SHORT FINAL; MY FLT DIRECTOR FLAGGED 'COMPUTER.' AFTER BLOCK-IN; THE PIC WAS ARGUMENTATIVE ABOUT THE DEV AND SAID WE WERE AT 2500 FT WHEN I BEGAN TO BECOME ALARMED. THE SO BACKED ME UP AND WE INFORMED HIM WE WERE AT 1600 FT AND FULL SCALE DEFLECTION WITH MATCHING INSTRUMENTATION. THAT EVENING; AFTER CREW REST AND PRIOR TO THE NEXT LEG WHICH I WOULD FLY; THE PIC INDICATED TO ME THAT HE FELT THAT HE HAD NEVER LEVELED THE ACFT OFF AT 2500 FT WHEN I CALLED GS ALIVE. HE STATED HE WAS VERY TIRED AND HAD NOT FLOWN IN 6 WKS. PERHAPS STANDARDIZED AUTOPLTS IN THE CARRIER'S FLEET COULD HAVE AVERTED THIS. I FEEL THAT HE SHOULD HAVE GIVEN THE LEG TO ME IF HE HAD ANY DOUBTS ABOUT HIS FATIGUE; ONCE ENRTE. HAVING NEVER FLOWN WITH THIS CAPT; IT IS DIFFICULT FOR ME TO JUDGE HIS CAPABILITIES OBJECTIVELY. I DID NOT FEEL HE ERRED ON THE SIDE OF SAFETY; HOWEVER.