master caution lights up when on approach to landing?

[Joch1955]

Picked up the module recently and having been slowly learning it. I have been practicing airfield landings to better understand how the "Trim" works.

When on final approach to land (gear down, flaps down, speed around 130 kts, on 8 degree AOA, trim to be more or less hands off), the master caution lights keeps going on, but with no associated warning.

I checked the manuals, but can't figure out what it is. I am thinking it may be related to the Trim or slow speed?

[Alpiinoo]

3 hours ago, Joch1955 said:

Picked up the module recently and having been slowly learning it. I have been practicing airfield landings to better understand how the "Trim" works.

When on final approach to land (gear down, flaps down, speed around 130 kts, on 8 degree AOA, trim to be more or less hands off), the master caution lights keeps going on, but with no associated warning.

I checked the manuals, but can't figure out what it is. I am thinking it may be related to the Trim or slow speed?

 Can you add track?

[Brun]

Hook bypass switch will make the AOA indexer flash if it's not set to 'field' and the hook is up. Been a while since I ran into that tho and I don't remember it triggering master caution, unless that happens at a specific altitude AGL?

[Joch1955]

Looked into it again and I think I figured it out, most likely candidate seems to be a low fuel warning triggered by the FPAS. As I understand it, the FPAS will trigger the Master Caution light when it calculates you will only have 2000 lbs of fuel until you reach your Home location as designated in FPAS. In the scenario I am playing, "Airfield VFR landing" on the Nevada map, you start with around 2200 lbs and land on the runway with almost exactly 2000 lbs remaining. In other scenarios where you start with more fuel, I don't have that issue.

Thanks for the help.

[Tusky]

hace 1 hora, Joch1955 dijo:

Looked into it again and I think I figured it out, most likely candidate seems to be a low fuel warning triggered by the FPAS. As I understand it, the FPAS will trigger the Master Caution light when it calculates you will only have 2000 lbs of fuel until you reach your Home location as designated in FPAS. In the scenario I am playing, "Airfield VFR landing" on the Nevada map, you start with around 2200 lbs and land on the runway with almost exactly 2000 lbs remaining. In other scenarios where you start with more fuel, I don't have that issue.

Thanks for the help.

Check if the HOME FUEL caution is displayed on the left DDI. It should be triggered if it's condition you are describing.

Edited March 14, 2023 by Tusky

[rob10]

Always check the bottom of the left DDI when the Master Caution goes off.  Any cautions/advisories will show up there and usually give you an indication of what's wrong.

[Joch1955]

22 hours ago, Tusky said:

Check if the HOME FUEL caution is displayed on the left DDI. It should be triggered if it's condition you are describing.

 

yes that was it, HOME FUEL shows up on the left DDI. Thanks.

[markom]

It's #1 most annoying alert in hornet :-). I especially hate it when it starts beeping while I'm trying to land. Like... I KNOW, I GET THE IDEA DAMNIT. STOP IT.  I also can't seem to find a reasonable way to silence it, but that just may be me.

[Sarge55]

Go into FPAS and change the Home waypoint to an unassigned waypoint. That should stop the caution showing up. 

[TonyG]

Ongoing bug that is still not fixed. Still  

 

[SickSidewinder9]

Really annoying that it's not fixed yet.  It's not a simple if/then or try/case to add?  The problem with setting to an unused WP is that it breaks the FPAS and then I don't seem to be able to reset and use it again.  Or I can't set a new Home.  Whichever it was.  Functions break.

Edited March 18, 2023 by SickSidewinder9

[Tholozor]

Home waypoint selection is only available when the FPAS is able to calculate the HOME FUEL caution, otherwise the home waypoint is crossed out and selection arrows removed (this is correct as-per the NATOPS). The HOME FUEL caution logic should not be active with weight-on-wheels, the refuel probe deployed, or for 5 seconds after a new home waypoint is selected while the logic kicks back in.

"Unused" waypoints are still technically viable coordinates, as all zeroes would be the position where the equator meets the prime meridian. Since the waypoint is so far away, the FPAS loses its ability to calculate HOME FUEL, as the remaining fuel would be far below what the aircraft can carry (at least in regards to the location of the theaters available to us in DCS), and home waypoint selection becomes unavailable.

One main reason why HOME FUEL is so common on landing (that I've noticed) is due to the power corrections needed to maintain a smooth glideslope. The fuel flow rate fluctuates rapidly, causing the FPAS to reassess the HOME FUEL caution constantly (depending on the home waypoint location and current fuel on board), resulting in the calculation to bounce above and below the 2,000-pound threshold, triggering the caution over and over.

Edited March 18, 2023 by Tholozor