Just flown an approach in the lovely new B737-800 but experienced a problem that had never happened in the B737-600/700.With both autopilots (and autothrottle) engaged the airplane flies a stable ILS approach and then suddenly drops below the glideslope. It tries to pitch up to re-capture the glideslope, the trim wheels are whirring like mad but it fails to re-capture. A/T goes from Speed to N1 and aircraft climbs away.Not sure why?? Just to be sure that the aircraft is not heavier than I have told the FMC it is, I have checked that ZFW figure is the FMC is the same as that in the Load Manager program.

Have you set VREF?Goto the FMC Approach page and select the Flaps you'll be using for finals. To do this,click the Right Select Key corresponding to the flaps you'll be using.You'll see that the Flaps/Speed value will be added for you.You now have VREF, add 5 to that to obtain VREF+5. This is the speed you should be at crossing the threshold.It sounds like your bird is stalling due to a misconfiguration. John http://homepage.eircom.net/~eamonnmca/images/logo_ba.JPGwww.bavirtual.co.uk Senior Captain Simflight.com Staff Reviewer