Written Test Question on To/From Indication and Waypoints

[Guy Morton]

On a practice test for my IFR written, there was a question about how to identify a missed approach point on an RNAV (GPS) approach. The MAP on the chart provided was a fly-over GPS way point at the approach end of the runway (no VOR in the procedure at all). One of the answer options was "When the To/From indicator changes." When I practice my approaches, I can watch way points "move under" the aircraft on the screen, or I can track the diminishing distance. But there is no "To/From" indicator like there is on my VOR, bit apparently the "To/From" change was the correct answer.

The explanation was: "RNAV allows the pilot to fly to a predetermined point by using waypoints. At the missed approach waypoint (MAP BIBPA), the TO/FROM indicator will show station passage."

That has not been been my experience unless there is another feature on the screen that I have been overlooking.

Am I missing something?

 

[MacFlier]

The to/from indicator should switch from TO to FROM once you fly over the MAP. To see this, you have to have the CDI on the GPS (430 for example) set to GPS and the flag on the slaved VOR1 should flip. You can also see this on a HSI like in an Aspen EFD or a G1000.

 

[Guy Morton]

The to/from indicator should switch from TO to FROM once you fly over the MAP. To see this, you have to have the CDI on the GPS (430 for example) set to GPS and the flag on the slaved VOR1 should flip. You can also see this on a HSI like in an Aspen EFD or a G1000.

Great answer. That now makes sense. Thanks! I was searching for some indication that the GPS unit would mimic that function. My mind didn't even go to the slaved VOR.
Thanks again!

 

[write-stuff]

The MAP represents the end of the road (until you resume sequencing for the missed approach procedure). The MAP remains behind you.

 

[flyingron]

Depends on the unit. WAAS units will tell you that you hit the MAP without needing to reference any flags. Some units automatically start sequencing the missed approach, others require a button push.

 

[Jim K]

Depends on the unit. WAAS units will tell you that you hit the MAP without needing to reference any flags. Some units automatically start sequencing the missed approach, others require a button push.

They do? I thought requiring a button push to switch to the missed approach procedure was part of the tso standard?

 

[Larry in TN]

They do? I thought requiring a button push to switch to the missed approach procedure was part of the tso standard?

The FMS units in transport jets automatically sequence to the MAP procedure without the need of a button push.

 

[flyingron]

They do? I thought requiring a button push to switch to the missed approach procedure was part of the tso standard?

Well sort of. THe Garmin GNS480 will put automatically sequence to the first leg of the MAP. After that you'll need to SUSP it to get it to proceed further.