737 FMC Intercept Course.

[mangatete]

Question if anyone has the answer," When flying on a intercept heading, to intercept an LNAV (inbound course) to a waypoint, does the progress page display track miles to run to the next waypoint or just the direct distance to the waypoint from the aircrafts position?
I use the intercept course function LSK 6R regularly when making a visual approach by extending the runway centre line back outwards, or the (final approach track) to a waypoint on the final approach that is inside my anticipated base turn. As the aircraft is flown toward a point on this extended centre line I use the progress page to monitor the track miles to run to calculate the appropriate path required. Also the vertical deviation indicator on the EHSI is providing guidance. However again is this based on a track distance to the intercept point of the extended centre line, or is it just a direct distance from the aircraft position.
Cheers mang.

[shlittlenellie]

Whenever direct to a waypoint is selected, whether that is with 'direct to' or 'intercept course', the distance calculated and displayed is always simply direct to the waypoint from present position and not direct to that part of the new leg that you're currently pointing at (it is always irrespective of the current track of the aircraft). The only difference with 'intercept leg to' is that it creates a specific LNAV course suitable for intercepting (perfect for a non-precision approach or re-intercepting the centreline of an airway).

Try it next time in the aircraft - both cases - and the distance will be the same, even though the LNAV magenta line will appear differently.

[mangatete]

Thanks sh. I did try it today with a large enough triangle to check this out, and sure enough the progress page only showed the direct distance to first waypoint followed by total distance of all subsquent waypoints. However the VNAV path calculations did take the extra track miles into the equation by creating a phantom waypoint at the intersection of the actual heading and the intercept of the track. This is great for getting a more acurate indication from the vertical deveation indicator on the EHSI. I must check the distance to run at L2R on the descent page next time and see if that shows direct distance to next waypoint or total track miles via the intercept point.
Cheers mang.

[mangatete]

R2 on descent page shows total distance to next waypoint ie (distance to intercept point and then to next enroute waypoint or EOD.) when conducting a hdg to a intercept course.

Cheers