correct as is FPAS locks and does not allow to change HOME WP

[escaner]

In many cases, when selecting an FPAS home waypoint, the system displays the FPAS advisory and removes the ability of changing the home waypoint. This probably happens more frequently when the CLIMB function is selected, but it is not always required.

According to the manuals, this should happen only in case of a malfunction in the system that does not allow the FPAS system to calculate home fuel caution anymore, which is not the case in this example: track attached.

fpas-locked.trk

[BIGNEWY]

reported to the team for checking thank you

[Lord Vader]

Hello @escaner

According to the public documentation, this is working as intended. 

Regarding the HOME Fuel selection, it will be crossed out if FPAS cannot calculate the HOME FUEL caution. This occurs, not only when there's a malfunction, but also when it goes beyond parameters, for example, if TAS exceeds Mach 0.9 the range at current Mach and altitude is invalid. In your track, you pass Mach 0.90 when the issue occurs, regardless of pressing the CLIMB button or not (that seems to be a coincidence). If you reduce below Mach 0.9 the option will be uncrossed. This is a correct depiction.

Hope this helped you. 

[escaner]

Hello @Lord Vader,

Thanks for your help I didn't know this does not work above M0.9.

Another case where I have found this is when selecting as HOME an "undefined" waypoint by mistake. Same example, using WP4, which is not in the route and defaults to N0º E0º. Once the system enters the advisory FPAS status, I am unable to change it to the correct home waypoint. Track attached.

If this behavior is also correct, there must be a way to select another home waypoint, right?

Thanks!

fpas-locked2.trk

[Tholozor]

If the HOME FUEL caution cannot be calculated by the FPAS, the home waypoint is crossed out and the selection arrows are removed. Every waypoint 0-59 is valid for selection, even if it's all zeros (which is a valid coordinate). One thing you could do is if your home waypoint selection is locked in this manner, is just edit that selected waypoint to the desired location or a location more nearby so the FPAS can calculate the HOME FUEL caution and re-enable home waypoint selection.

Edited November 23, 2022 by Tholozor

[Lord Vader]

13 hours ago, escaner said:

Hello @Lord Vader,

Thanks for your help I didn't know this does not work above M0.9.

Another case where I have found this is when selecting as HOME an "undefined" waypoint by mistake. Same example, using WP4, which is not in the route and defaults to N0º E0º. Once the system enters the advisory FPAS status, I am unable to change it to the correct home waypoint. Track attached.

If this behavior is also correct, there must be a way to select another home waypoint, right?

Thanks!

fpas-locked2.trk 531.23 kB · 0 downloads

Hi @escaner

The crossout indicates that something is out of parameters. Unfortunately, it's the logic we got for this very specific calculation.

I agree with @Tholozorsuggestion, just edit that specific waypoint to make it plausible for a calculation. Remember, the system needs 5 seconds to get a calculation.