B737 ALTDEV SNA. RPTR CITES LACK OF TRAINING IN FMC OPS AND PROCS TO USE AUTOFLT IN STAR ARRS.

Narrative

EASTSIDE 3 ARR INTO SNA REQUIRES 190 KTS AT KAYOH; AND WE WERE CLRED TO CROSS AT 7000 FT. IN THE B737 WITH VNAV CAPABILITY WE ARE RECOMMENDED TO SET THE NEXT ALT ON THE ARR IN THE MCP -- NOT THE LOWEST ALT -- THEN PROGRAM THE FMC. HOWEVER; IT IS ACCEPTABLE ON A COMPLICATED PROFILE DSCNT TO SET THE LOWEST ALT IN THE MCP AND PROGRAM THE FMC FOR THE PROFILE DSCNT. IN THAT WAY IT SHOULD HIT EVERY ALT AND AIRSPD AUTOMATICALLY; IN PATH DSCNT. THE PROB THIS DAY WAS THAT ON THE EASTSIDE ARR WE ARE REQUIRED TO CROSS KAYOH AT 190 KTS; SO WE MUST USE FLAPS 5 DEGS. WHAT I DIDN'T KNOW WAS THAT AS SOON AS FLAPS ARE EXTENDED; THE FMC AUTOMATICALLY DROPS INTO VNAV SPD; AND IGNORES ALL PATH PROGRAMMING. ALTHOUGH I HAD 7000 FT AT KAYOH PROGRAMMED; WE DSNDED RIGHT THROUGH 7000 FT TO ABOUT 6600 FT. WE CAUGHT IT; BUT NOT BEFORE DSNDING THROUGH THE REQUIRED ALT. BOEING; AND ACR TRAINING DEPTS; SHOULD ENSURE THAT EVERY PLT UNDERSTANDS THAT WHEN FLAPS ARE EXTENDED; THE FMC DROPS OUT OF VNAV PATH AND INTO VNAV SPD. IF THE ALT IN THE MCP IS SET TO THE BOTTOM OF THE PROFILE DSCNT; THE AUTOPLT WILL IGNORE ALL FMC PROGRAMMING AND DSND IN VNAV SPD ALL THE WAY DOWN TO THE ALT IN THE MCP. SINCE THIS OCCURRENCE; I HAVE DISCUSSED THIS WITH MANY OTHER PLTS AND NOBODY KNOWS ABOUT THIS. IT IS VERY DANGEROUS.