Hello allSorry if this question was asked and resolved earlier.Recently, I have noticed that when I am performing a Precision ILS approach on my 737NG, I usally hit on the "App" button of the MCP to be established on the localiser.However, as soon as the Glidscope is active the 'APP' button tends to deactivate and does not reactivate even if i press that. However, the aircraft seems to descend perfectly on the glidescope?Any helpVybhava SrinivasanBangalore, India

Normal behavior.. the APP button lights when armed then light goes out on capture; however, the annuciator above the attitude indicator will display GS to provide status.

To add further - Don't trust the MCP lights, always verify statues on the PFD annunciation area. As was stated, the APP light goes "out" when capture commences. This is how Boeing designed it to work. The other reason (and most important one) is that once you enter this mode - you can no longer de-select the APP mode by pushing the MCP light but have to either re-tune the NAVS, press TOGA or turn of both F/D & A/P to exit the APP mode.Best,Randy J. Smith<<>>