Please correct me if I'm dreaming this up but this is something that is bugging me on my last few -11 flights.My past few departures have involved ATC vectors and a clearance direct to a waypoint on my route. I seem to recall that using DIR TO on the FMC would automatically engage NAV (reverting from HDG) on the autopilot, if I was on an intercept heading. Reading through the manuals, I can't seem to find anything to confirm/deny this. My last few flights with vectors to a navaid and using DIR TO, I had to press NAV explicitly. Can anyone (kindly) shed some light for me?Thanks!

Hello,Please sign your full name per forum rules, (or add it to your sig) thanks.This was copied and pasted from another post I made a while back but still pertains I think here."The Direct to function works but you have to at least be in what I think is called an intercept course or heading to the waypoint, or at least to the rough vacinity. So if your next waypoint that you entered in your Direct to page was at 220 degrees, but if you were past it and flying at a heading of 040 degrees then it wouldn't work, and nothing will happen. Try again, but make sure you first make any manual heading changes necessary to be facing the waypoint you are wanting then use the direct to option. After you do you'll also have to press Nav on the glareshield, since you will still be in heading mode."That post of course is saying to do what you already know. The difference is you thought it changes your mode automatically which I never seen happen and not sure if it was meant to to be honest.Hope this helps,

If you're on heading mode using the FCP, the AFS will never go to NAV mode automatically, regardless of what and how you change your route via the FMC. This would not be practical as there are moments when you want to work on your route while being on ATC vectors. This is the same for other aircraft like the Airbus FBW series...Markus

Great, thanks. Guess that's what happens when I take a few weeks off, lose some proficiency.

This would not be practical as there are moments when you want to work on your route while being on ATC vectors. This is the same for other aircraft like the Airbus FBW series...Markus

Have to correct you there mark. According to A320 FCOM vol2 34.31.41, selecting DIR to a waypoint in the airbus FMGC does actually put the aircraft back in NAV mode. Im kinda surprised i haven't heard about a lot of pilots complaining about it, i personally would find it a wee bit inconvenient at times.

Have to correct you there mark. According to A320 FCOM vol2 34.31.41, selecting DIR to a waypoint in the airbus FMGC does actually put the aircraft back in NAV mode. Im kinda surprised i haven't heard about a lot of pilots complaining about it, i personally would find it a wee bit inconvenient at times.

Thanks, I'm surprised to hear that actually. I don't remember seeing this on all my flights on the Airbus simulator. Might be a company option? Or then again my memory is just weak :)Markus

Thanks, I'm surprised to hear that actually. I don't remember seeing this on all my flights on the Airbus simulator. Might be a company option? Or then again my memory is just weak :)Markus

The NAV mode gets armed, but NOT activated until reaching the intercept point: "If the current AP/FD lateral mode is HDG or TRK, NAV becomes armed. If the NAV mode was engaged, NAV becomes armed. FCU HDG or TRK must be used to guide the aircraft. The ND displays an intercept point, if the intercept angle is less than 120

The NAV mode gets armed, but NOT activated until reaching the intercept point: "If the current AP/FD lateral mode is HDG or TRK, NAV becomes armed. If the NAV mode was engaged, NAV becomes armed. FCU HDG or TRK must be used to guide the aircraft. The ND displays an intercept point, if the intercept angle is less than 120

My understanding was that DIR-TO simply computes and activates a route from the planes current position to the chosen waypoint. it has nothing to do with the NAV mode of the AP on an MD-11. If you want the auto-pilot to follow the route that DIRTO computes, it must be in the appropriate NAV mode. Intercepts are totally seperate and unrelated to DIRTO as they are about the transition from HDG based direction control to route following. This is never relevant in the context of DIR-TO since the start of the computed route is behind you and pointing away (unless your heading was directly towards the waypoint) so you can never be on an intercept heading.