When I'm flying I arm VNAV the FMC is programed but when I reach the first altitube it just disconnects and when I try to connect it it wont light up.Any idea why?Kenneth

Hey.More information would be helpfull, are there any error messages in the FMC? Also what altitude do you have in the MCP? Make sure it is your cruise altitude or higher then your first altitude constraint or VNAV will disconect and alt hold takeover.Hope this helps,David.

>Hey.>>More information would be helpfull, are there any error>messages in the FMC? >>Also what altitude do you have in the MCP? Make sure it is>your cruise altitude or higher then your first altitude>constraint or VNAV will disconect and alt hold takeover.>>Hope this helps,>>David.I think it is that because when I set FL13 from FL12 I could activate it thanks!Kenneth