RWY mode on VSI?

[dlrk]

What is the functionality where RWY appears above the VSI and a path is drawn on the PFD SYN VIS? I'm guessing it's displaying 3-degree glide path?

[Lightcivvie]

IRL, when VNAV mode is engaged, and you have altitude constraints on your FMS flight plan waypoints, the location above the VSI tape will show the next altitude constraint. 

RWY is displayed above the VSI instead of the next altitude constraint when you have an approach loaded, and the next waypoint on your flight is the runway. On your FMS 'LEGS' page, you will also see 'RWY' displayed on the right side of the waypoint list, just before the 'MISSED APPROACH'.

Sometimes (depends on the FMS software version) you will see an altitude value instead of 'RWY' on the 'LEGS' page. 

If you see 'V-MDA' on the 'LEGS' page, you are not allowed to use VNAV past the final approach fix, this is an official aircraft limitation.