HUD Navigation source question

[Pinefang]

I know that the bottom left hand corner of the HUD will tell you where the navigation information is coming from but how do you cycle that indication on the HUD between STPT, TGP, TAD etc? For instance say I have been hitting an area for the last hour with different munitions and it is time to go home and say the indication on the HUD is TGP or TAD how do I know that where the tail on the VVI is pointing is to the selected base, or is it directing me back toward the target area? Maybe I need to study the switches on the CDU and get a better understanding of what indications they produce. Hope this isn't a confusing question if so I think I can elaborate if needed.

Edited March 22, 2014 by Pinefang
Add second to last line

[ralfidude]

There are two markers.

 

One is a dotted marker, this will point you to something that you have hooked on to (Can't remember if it also shows you your currently designated SPI or not), while the solid marker is the one that shows you where your steerpoint is.

 

So the dotted one looks like this if you skip to 0:30

 

At about 1:13 you see two things, the dotted one is showing you what I have hooked on the TAD (which I think is also what you have selected as your SPI otherwise), allthe while the currently selected waypoint is shown on the bottom right as a solid box with a line through it. It's like that because the box is there in front of us, but if it was off the nose like somewhere to the left or right, then you would have a line coming out from the same place the dotted line is (but solid) pointing towards the currently selected waypoint. You can see it happen exactly at 1:18. So at 1:18 you are seeing what I have hooked to the left (the aricraft, or target zone, wtvr) and the solid line to the right telling me that is where my currently selected waypoint is.

 

 

If you want to go home, then all you need to do is scroll through your waypoints and select the home waypoint, which is usually wpt 1.

[Yurgon]

I know that the bottom left hand corner of the HUD will tell you where the navigation information is coming from but how do you cycle that indication on the HUD between STPT, TGP, TAD etc?

 

If I understand you correctly, the question already contains a misunderstanding. :smilewink:

 

The string in the lower left corner of the HUD doesn't have to do with navigation, it's simply the SPI generator, and thus commands like "Slave all to SPI" depend on this information. The SPI generator can be set with TMS Forward Long on SOI (Make SPI) or TMS Aft Long (SPI to Steerpoint).

 

In the manual, the Chapter "Understanding SOI and SPI" under "Cockpit Controls" goes into more detail. I'll just quote part it, because it should really answer your question. :thumbup:

 

Sensor Point of Interest (SPI)

 

A SPI is a 3D point in space that the systems use as a shared reference location to cue weapons, aim sensors and send over the datalink. This is a key component of the A-10C and helps you to locate targets with onboard sensors (Targeting Pod, Tactical Awareness Page, HUD, Maverick and AIM-9), then cue weapons and slave sensors to it.

 

The default SPI is the steerpoint. Once a sensor has been set as the Sensor Of Interest (SOI), the sensor may designate the SPI. Once a SPI has been defined, the SOI can change without changing the SPI. The current SPI generator is always indicated in the lower left corner of the HUD.

 

The system is always tracking a SPI with the current steerpoint being the default SPI (such as when the aircraft is powered). The exception is if the SPI is commanded to steerpoint but there is no valid steerpoint because the CDU is not available.

[Pinefang]

Thanks for the help guys. After reading the quoted chapter and watching Ralpidudes video an in depth understanding and proficient usage of all of the targeting options is quite a study. All of this well take a while to get my head wrapped around for it to become second nature. I think I have the basics of a lot of it now and can build on that.