Question: GTN 750 glideslope

[Oscar Avalle]

I have a question for the group....

 

Yesterday I was flying an ILS approach. The frequency Id was ok, the LOC came in fine, but the Glideslope was intermittent. It came up and then disappeared from the ASPEN display as if the signal was intermittend.

 

I was wondering if this is something that already happened to some of you guys, if this is an antenna problem, and what could I do about it...

 

Thanks for any input on this...

[Bob_Belville]

Do you have a 2nd GS receiver in your #2 NAV?

[Oscar Avalle]

yes, should have tried that...

[jlunseth]

I have a 430AW and just once we had no glideslope on an approach to KIXD.  We should have had the ILS on the Nav. 2, which is a KNS80, but we did not.  We went around and the Glideslope showed up the second time.

[gjkirsch]

If I am too far above the glideslope, it will not show up.  The approach ends up looking like a localizer approach until I descend far enough for the glideslope to show up

[Marauder]

Oscar -- on the Aspen the VDI for the glideslope will disappear if the signal is intermittent. I found that if I am not within 3 miles of the glideslope intercept point and within 1 mile of the final approach course with the GTN I normally will not get a steady VDI indication.

[Marauder]

And as a datapoint, I swear my Narco 12D+ gives me more latitude!

[RocketAviator]

I can tell you from my recent sounds somewhat close experience that the GTN will drop the glide slope to my G500 if not stable.  i found the problem in one of my towel bar antenna's after replacing the antenna the signal was 4 times better, this was based on a test on the ground using the avionics shop ILS equipment.  

I am seriously thinking of looking into and seeing if the wing tip antennas will work in my Rocket and if so I might try them.

If you have an avionics shop they should be able to perform the same test using their test / setup ILS equipment.

Not sure where you are located but John Miller at Crystal Avionics in New Braunfels did the work for me. 

 

I fly a fair amount in IMC and I had my autopilot out this last week and had to make several flights in IMC while it was out.... All I can say is an autopilot to me is not just a luxury it is almost a hard necessity for increased saftey in IMC....  I know I can fly without it if I have to but I sure dont like too!

 

Good luck,

[Oscar Avalle]

I can tell you from my recent sounds somewhat close experience that the GTN will drop the glide slope to my G500 if not stable.  i found the problem in one of my towel bar antenna's after replacing the antenna the signal was 4 times better, this was based on a test on the ground using the avionics shop ILS equipment.  

I am seriously thinking of looking into and seeing if the wing tip antennas will work in my Rocket and if so I might try them.

If you have an avionics shop they should be able to perform the same test using their test / setup ILS equipment.

Not sure where you are located but John Miller at Crystal Avionics in New Braunfels did the work for me. 

 

I fly a fair amount in IMC and I had my autopilot out this last week and had to make several flights in IMC while it was out.... All I can say is an autopilot to me is not just a luxury it is almost a hard necessity for increased saftey in IMC....  I know I can fly without it if I have to but I sure dont like too!

 

Good luck,

Good point about the Antenna. Mine is about 20 years old.... I went to the hangar today and cleaned it. I plan on going flying tomorrow and will check how it goes.