When do I use the TRK/FPA button?

[John F 1]

I notice in the Aerosoft Airbus X Extended - Non Precision Approach Guide V1 it tells me to select the TRK/FPA on the FCU to "get the birdie"

This is the first time I have seen this I think, so when and why would I need to use it?

John F

[Redwood 2]

Hi John,

The TRK/FPA button as you read is used during some non-precision approaches, namely the localizer, and RNAV approach. For instance, on the LOC approach when cleared to intercept the localizer, push the LOC button, look for LOC in blue meaning it is armed to intercept, and when cleared for the approach, "bird on". Usually there are a few step down fixes on a localizer approach. Use either open descent, or FPA of 3.5 to 4.0 to descend to any intermediate altitudes at flaps 2, 180 kts if you can. Try to be flaps full, gear down, and managed speed by the final approach fix. Take a look at a localizer approach plate if you get a chance. On the plan view you will see the FPA from the FAF to the runway, usually 3.0 degrees. As you approach the FAF pre-set that value, (when level) say 3.0 in the FPA window, and at .3 miles from the FAF pull the FPA knob to start the descent. Watch the green yo yo on the PFD, and modulate the FPA a few degrees if needed to keep the green ball centered. This gives a nice stable descent to the runway.