What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

GPS-175 question

P

prkaye

Well Known Member
I've been playing around with the Aviation Trainer software to become more familiar with my GPS-175. While i have it flying between waypoints, or in a hold, and am watching in the map view, sometimes a number (e.g. "+24") will pop up in a black square near the aircraft position, as shown in the example here:

I haven't come across this in the manual. Do an of you know what this means?
 
Ah, ok thanks!
Another thing that i'm finding weird in the Aviation Trainer software is that it doesn't seem to do holds correctly. I program a hold with leg time set to 1 minute. But it only does about 45 second legs. The GPS-175 simulator display screen starts the timer appropriate points, but then after about 35 seconds it says "turn heading... in 10 seconds" , and then at about 45 seconds it says "turn heading ... now". Isn't this about 15 seconds too early? I'm still an IFR student, but my understanding is that the inbound leg time should be 1 minute from the time you complete a turn onto the inbound track to the time you begin the turn at the fix. Is this possibly just a quirk of the aviation trainer software?
 
Last edited:
Here in the US, many holds associated with gps approaches have been converted to ‘xx mile legs’ instead of the old standard of time. It’s easier for the gps to do these. As far as I can tell the actual distances xx vary all over the place. And - while poor advice to give to an instrument student - unless atc is actually running ‘timed approaches’ (anyone ever get one of these?), no one will care if you turn in a bit early. After all, if you were doing it the old fashioned way (trial and error) you could always claim to have mis-guessed the wind. It’s also possible that the simulator has a programmed tail wind on the outbound leg, so you should turn in early to make the inbound leg a full minute. Lots of possibilities, need more details.
 
Useful tool

I have to say the 175/375 emulator has been very useful to me in learning the switchology, in particular the differences between "load" and "activate" approach, the direct to function to a fix, and the suspend/unsuspend function. the iPad version is great to practice with on a trip.

Took a while to figure you can start at your home field and visualize approaches in the local area.
Figs
 
and there’s more than one guy under that “G3xpert” here.

One thing about that app though, it is pretty much dated… I’ve used it about 6 months ago for some refresher training prior to my NAT crossings, and sure helped visualizing some of the functions. But some of the stuff has been revised in the real life version and not current anymore in the app sim version.
 
Another non-standard thing i just discovered it's doing. For teardrop (offset) hold entries, everything i've read says on passing the fix you turn to a heading that makes an angle of 30 degrees or less from the outbound track. The GPS-175 simulator is consistently guiding me to turn to headings making an angle of 35-45 degrees from the outbound track. I mean, it still works, but why wouldn't the machine be giving guidance that agrees with standard practice?
Next week I'll test these behaviours out on the real GPS-175 in the aircraft, for comparison.
 
You must log in or register to reply here.
Back
Top