Glide Slope warning when T/O with runway ILS tuned

[AngelOfAttack]

When taking off, it's standard practice for us to tune the T/O runway ILS just in case especially when there is no other navaid need (eg. RNAV SID)

But When I do it in IXEG 733,I got "Glide slope" GPWS call right after lift off, and I see the GP indicator on my EADI show full up, only after climb for about 200 feet, the GP moved down and the alarm shut off.

It's not even a runway with same ILS frequency on the opposite way, there is no ILS on the other side, I know there might be some sort of radio interface might cause such indication, but I believe it should not trigger the GPWS then?

BTW I have NAV1 on ILS while NAV2 on VOR.

[Litjan]

I have seen this, too - I am not sure how the real world deals with this, I believe there will be very poor reception on the upwind side so the GS doesnt show. But I don´t know if there is any code to "suppress" a GS warning if the aircraft is on the upwind side in the real GPWS? If an ILS is tuned and the plane is sufficiently below the GS, the warning will play.

We are not doing anything with the glideslope as transmitted by X-Plane.

Procedures will differ between airliners, but we never tuned the ILS for departure, unless it was part of the SID navigation (like at Marseille or Orly).

[AngelOfAttack]

41 minutes ago, Litjan said:

I have seen this, too - I am not sure how the real world deals with this, I believe there will be very poor reception on the upwind side so the GS doesnt show. But I don´t know if there is any code to "suppress" a GS warning if the aircraft is on the upwind side in the real GPWS? If an ILS is tuned and the plane is sufficiently below the GS, the warning will play.

We are not doing anything with the glideslope as transmitted by X-Plane.

Procedures will differ between airliners, but we never tuned the ILS for departure, unless it was part of the SID navigation (like at Marseille or Orly).

I'm not sure why IXEG would pick up G/S on the upwind, literally miles away from the GP beam, I don't think I have ever seen that on PFD, but you know that's not where eyes would be in a take off...

I see some general GPWS introduction says it requires RA be over 30' and gears down, not sure if it's also required on 733 but sound reasonable.  But even if it's there, if you retract gear a little bit slower, it might still trigger one or two calls then.

[Pils]

51 minutes ago, Litjan said:

But I don´t know if there is any code to "suppress" a GS warning if the aircraft is on the upwind side in the real GPWS?

Y’all could also consider looking at Saso’s OpenGPWS.

[Litjan]

3 hours ago, AngelOfAttack said:

and gears down

That may be the missing condition - I will check the code. As for the GS deflection, I can verify this with DATA OUT, I think there is a field for glideslope deviation.