PLT OF B737-800 RPTS LIKES AND DISLIKES REGARDING THE TEST VERSION OF RAAS INSTALLED ON AN ACFT UNDER THEIR COMMAND.

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I HAD THE OPPORTUNITY TO FLY THE SAME B737-800 ON 2 DAYS. THAT ACFT IS EQUIPPED WITH THE TEST VERSION OF THE RAAS. I WANT TO PASS ALONG THE FOLLOWING OBSERVATIONS AND THOUGHTS ON THIS SYS. ON DEP/TAXI OUT IN SEA; THE RAAS WAS QUITE INACCURATE IN TERMS OF ANNOUNCING THE ACFT'S POS IN RELATION TO THE TXWY/RWY. WE WERE CLRED FOR TKOF ON RWY 16L AS WE APCHED THE DEP END OF THE RWY AT TXWY C. WE DID NOT STOP OUR TAXI AS WE MADE THE TURN AT TXWY C TO LINE UP ON RWY 16L. IT WAS NOT UNTIL WE WERE WELL ONTO THE RWY THAT THE RAAS ANNOUNCED; VERY LOUDLY; 'APCHING RWY 16L.' THERE ARE SEVERAL PROBS HERE. FIRST; THE INFO IS NOT TIMELY; THEREFORE; ALMOST USELESS BY VIRTUE OF BEING TOO LATE. SECOND; THE ANNOUNCEMENT IS AN UNWELCOME DISTR AT A VERY CRITICAL JUNCTURE. THE CREW IS PREPARING FOR TKOF; WATCHING/LISTENING FOR TFC; COMMUNICATING WITH ATC; RUNNING A CHKLIST; AND WEIGHING A NUMBER OF VARIABLES; POSSIBILITIES; AND THREATS WHICH MAY BE ENCOUNTERED IN THE NEXT COUPLE OF MINS. THIS LOUD; NEAR USELESS; RAAS ANNOUNCEMENT BECOMES JUST ANOTHER SAFETY THREAT. THE STERILE COCKPIT ENVIRONMENT EXISTS TO MINIMIZE UNNECESSARY DISTRS DURING CRITICAL PHASES OF OPS FOR A GOOD REASON. RAAS SEEMS TO VIOLATE THE INTENTION OF KEEPING THE COCKPIT CLR AND UNCLUTTERED; AND THEREBY REDUCING THE THREAT LEVEL. LEAVING MCO; THE POSITIONING OF THE ACFT AND SUBSEQUENT ANNOUNCEMENT 'APCHING RWY 18L' WERE MORE TIMELY IN THAT THE ANNOUNCEMENT OCCURRED PRIOR TO XING THE HOLD SHORT BARS FOR THE RWY. I WOULD STILL CHARACTERIZE THE ANNOUNCEMENT AS DISTRACTING UNWANTED/UNNEEDED INFO AT A CRITICAL TIME DELIVERED AT A LOUDER THAN NECESSARY VOLUME LEVEL. ON ARRS; THE ANNOUNCEMENT APCHING THE RWY IS; AGAIN; OF QUESTIONABLE VALUE AND TIMING. IT'S ALSO TOO LOUD. THIS ANNOUNCEMENT HAS THE POTENTIAL DURING CAT III OPS TO BE A REAL PROB. THERE IS GOOD REASON WHY OUR PROCS WERE DEVELOPED TO KEEP TO AN ABSOLUTE MINIMUM THE AMOUNT OF UNNECESSARY ACTIVITY; AURAL AND OTHERWISE. I WOULD SUGGEST THE SAME CONCERNS APPLY TO ALL APCH SCENARIOS. I DID; HOWEVER; LIKE THE DISTANCE REMAINING CALLS. I COULD SEE AN ENHANCED LEVEL OF SITUATIONAL AWARENESS AND SAFETY ON A LOW VISIBILITY LNDG ROLL; PARTICULARLY AT AN UNFAMILIAR FIELD. THE RAAS COULD BE IMPROVED WITH A SIMPLE CHANGE IN SYS PHILOSOPHY. THE SYS SHOULD BE QUIET UNTIL IT SENSES SOMETHING WRONG; AT WHICH POINT THE ANNOUNCEMENT WOULD BE FOLLOWED BY THE CREW'S IMMEDIATE REVIEW OF THEIR SITUATIONAL AWARENESS. THIS IS SIMILAR TO THE CURRENT SWITCH; WARNING LIGHT; AND AURAL WARNINGS USED BY BOEING. DON'T WARN A CREW ABOUT SOMETHING NORMAL. MY FAMILY'S AUTOMOBILE HAS A VERY ACCURATE GPS BASED NAV SYS TIED TO A MOVING MAP DISPLAY. THIS IS RELATIVELY OLD TECHNOLOGY AVAILABLE ON MOST CARS TODAY. IT WORKS GREAT. I WOULD MUCH PREFER THIS KIND OF PASSIVE RWY/TXWY AWARENESS SYS WHICH COULD BE DISPLAYED ON ONE OF THE COCKPIT DISPLAY PANELS OF ALL OF OUR ACFT (DU; EHSI; NAV DISPLAY; OR RADAR DISPLAY). THE TECHNOLOGY EXISTS; IT WORKS; AND IMPROVES SITUATIONAL AWARENESS WITHOUT JEOPARDIZING OVERALL SAFETY. IT ALSO DOES IT IN A NON-INVASIVE WAY. THE CURRENT RAAS IS NOT A GOOD SOLUTION TO ENHANCING SITUATIONAL AWARENESS AND; IN MY OPINION; ACTUALLY DECREASES THE OVERALL LEVEL OF SAFETY IN THE COCKPIT.