Target Aspect

[jeepster]

I try to understand the fundamentals of interception und read the relevant chapters in P-825. To build a gameplan for a stern conversion the most important thing seems to determine target aspect (ta) to compute and build lateral separation as turning room. For T-45 they use the TA Vector shown on the trackfile symbol after locking the bandit. But this graphical procedure seems to be a roughly estimation. How does this procedure work in the hornet ?

Is ta computed and shown anywhere ? All relevant data seem to exist because the ddi is drawing a vector.

Does the following calculation leads to an accurate result ?

TA is defined as angle between bandit bearing (bb) and bandit reciprocal heading (br). After locking the bandit the ddi shows bandits heading so that it is easy to calculate br. bb should be delivered by the bra information also from the ddi. the difference between both angles should be ta.

Can someone with expertise please take a look at it ?  

[Tusky]

If you lock the target in STT and go to the STORE page, you will see in the lower half of the screen a list of target's data. 

Amongst those there is ASPCT which is measured clockwise in a 360° format from the tail of the target: 0° at the tail and increasing to 360° to the left side of the target. You only need to do the corresponding math to find the ASPECT which is measure 0°-180° left or right; just take into consideration that there is ASPECT OFF TAIL (AOT) or ASPECT OFF NOSE (AON) and if I remember correctly, NAVY uses the former and USAF uses the latter.

What I suggest you to do though is to select one specific aspect you wish to have as a reference and see where the TARGET ASPECT ANGLE POINTER on the NIRD (the arrow on the circle) of HUD is pointing to judge your position. I use 40° as a reference and I know that my target is at 40° L/R when the arrow is pointing approximately to the comma of the RNG (right aspect) or the comma of the G (left aspect). I don't use the vector on the DDIs since it is too small.

Edited February 14, 2023 by Tusky

[bonesvf103]

I think a TA of 180 means the target is heading directly away from you (you are chasing his tail) not toward.  Toward would be TA=0 (you are nose to nose).

For instance, let's say the bandit is right in front of you and you are heading 360.  Let's say he is also heading 360.

Bandit bearing=360

Bandit reciprocal heading=180

TA=BB-BR=360-180=180

Thus TA=180 is he's heading away.

Let's try it with bandit bearing=0 and you are both heading 360 (or 0)

0-180=-180 which is still 180 degrees, bandit is heading away.

Let's try different headings.  He is heading 090, you are heading 270, nose to nose:

TA=BB-BR=270-270=0.  Thus bandit is heading toward you.  Recall his heading is 090 so his BR is 090+200-20=270.

Now let's try with him off to the left of your nose by say 20 degrees.  You are heading 270, he is heading 090.

TA=BB-BR= (270-20)-270=-20.  Thus bandit TA is -20, or 20 left.

And if he was right of your nose by 30 degrees, you are heading 270, he is heading 090

TA=BB-BR=(270+30)-270=+30.  Thus bandit TA is +30, 0r 30 left.

Don't want to do math?  VIsualize it from the DDI and HUD data.  In the DDI, the little stick does not show the bandit's heading but rather the bandit's TA.  So if you have him as L&S on your DDI and the stick is pointing straight down, that means his TA is 0.  That does NOT mean he is headed right for your nose unless he happens to be dead center in your DDI.  He can be left of the center of the DDI and if the stick is pointing straight down, that means his nose is on you.  It is a common misconception to think that the stick is his heading and so if he was left of center on your DDI with the stick pointing down, one would think that he is flying parallel to you.  He is not.  It means he is to your left with his nose on you.

You can verify this by looking at him in the SA page.  You will see that he is heading right at you in the SA page, even though the stick in the radar DDI stik is pointed straight down, giving the illusion that he is flying parallel to you.

The way I visualize the stick for TA so I don't need to do the math is the stick shows me where the pilot of the bandit is looking straight ahead.  So if the stick is near the bottom right leg of the L&S star, he has to turn his head about 20 degrees to his right to see me.  Thus his TA is 20L or left 20 degrees:

The same in the NIRD circle.  What shows in the NIRD circle is his TA, the same as on the L&S start in the DDI.

Interesting to note is there is actually a number of degrees associated relative to the points of the L&S star:

 

v6,

boNes

[bonesvf103]

Follow up:

I looked at the MFD data as shown by the other poster where it shows aspect as being 180 deg and that it means the bandit is heading toward you.

I just tried it in the sim and although the stick showed straight down in the L&S star (0 TA) the MFD data said 180.  This leads me to believe that the MFD data aspect is a angle of the tail angle aspect (the star is angle off the nose).

To check this, I placed the bandit so that he had TA 20 off of the L&S star.  Sure enough, the MFD data said 200.  So it does appear to be off the tail.

The pages from the AWI manual above also confirm that TA=0 (off the nose) when the stick is straight down, and this angle off the nose approach is what is used in the AWI manual for intercept calculations and methods.

v6,

boNes

[Tusky]

The data shown in the STORE page is a not an ASPECT value but more of a 0-360 clockwise "bearing" off the tail of the target; you need to do the math to convert it to ASPECT which is 0-180 left or right. Another way to determine an accurate aspect angle is by doing the math between your heading (also indicated on the top of the radar screen) and the target's heading (indicated on the top left of the radar screen).

There is really no need to be that accurate though. Depending on what you are doing, equally important is how and how fast target aspect changes and what that means: does it increase or decrease? how fast does it increase/decrease? Is that good or not?

As I said, there are two ways of calculating ASPECT: off the TAIL or off the NOSE. HABFMs (High Aspect Basic Fighter Maneouvers) are those 1v1 dogfights started head on; even if the name itself supposes an ASPECT calculated from the tail (high is 180 and not 0) many people will still use BONESVF103 way of calculating aspect. There is no right or wrong way but just two different reference systems (OFF NOSE being probably the most common througout the air forces). So, when reading stuff or talking to be, poeple should be aware of what system is being referred to...

In the end:
- Is there a way to accurately calculate aspect: yes (STORE page in STT, comparison of headings, etc)
- Are there less accurate ways to determine it? yes (L&S vector in the RADAR page, TARGET ASPECT ANGLE POINTER on the NIRD, etc )
- Do you need a super accurate value: no (most of the times)
- Is aspect at a given time the only important factor: equally (if not more) important is how and how fast in changes in time
- Is there an universally accepted way of calculating it? No, it can be reference as OFF TAIL or OFF NOSE

Maybe other people may want to contribute (by no means I've got the ultimate "truth") but I hope it helps...

Edited February 15, 2023 by Tusky

[bonesvf103]

Thanks for your inputs Tusky.  Yes it is good to know that there are more than one method of doing it, some more accurate than others.  I prefer the one in the AWI manual (P-825) simply because with the ever fast dynamic nature of an engagement, am I going to be able to do that math under that kind of time crunch and pressure?  What if I left my calculator at home?  Haha.  But yes, if you wanted to go sharpen your pencil and you went right to the pencil sharpener to do it or you did a backflip, crawled further toward it, and then hopped the rest of the way to the sharpener, what difference does that make since you still end up with a sharpened pencil?  Well, I guess the efficiency is the difference but still...

I actually did not realize that there were the data in the STORES page when STT.  I remember that was added on later but either didn't pay too much attention to it or was just set in the P-825 way.  Great call about what ASPECT means in that.  The ASPECT label in that case is somewhat of a misnomer.

Another important thing to consider is drift.  You have to take cuts to make sure there isn't drift toward the cold side of things otherwise that means you are intercepting too far ahead of yourself and in all actuality drifting across your target's nose (and WEZ).  Of course if the drift is toward the hot side, then he is drifting into YOUR WEZ.

I also encourage more discussion about this.  It is fascinating to me.  I would like to know, for instance, how to employ AWI in the real situation.  The manual assumes that the target is non maneuvering, like intercepting a Bear or a tanker or other assets for formup.  So the whole gameplan thing based on TA and ATA is all well and good, but what about if your're interecepting a MiG-29 that is hellbent on killing you?  Also, it assumes that the engagement will go to the merge.  So what happens if you are happily following your gameplan then they fire a missile at you BVR?

Now I know there is a timeline that employs MRM in the manual.  But when does that get implemented?  When you are following the gameplan per the manual but then until you get to NLT than 20 nm then you switch to the timeline?

Good stuff.

v6,

boNes

[Tusky]

hace 1 hora, bonesvf103 dijo:

I prefer the one in the AWI manual (P-825)...

P-825 (NAVY) defines two different angles:

Target Aspect (TA) – Angle between BH [Bandit Heading] and the bearing from the bandit to the fighter (this is measured from the nose)
Aspect Angle (AA) – Number of degrees from the BB [Bandit Bearing - LOS from the fighter] to BH [Bandit Heading] ; defines the number of degrees to the bandit’s six o’clock (this is measured from the tail)

TA+AA =180° (meaning they are intercheangeable)

Regarding the timelines in the P-825, those are tailored around the T-45 (subsonic aircraft) and are just exercises which give an the idea of what a timeline is. The naval aviators will be introduced to the ones built around their platform (and their assumed opponents) once in the fleet...

 

[Aquorys]

On 2/14/2023 at 5:05 PM, bonesvf103 said:

I think a TA of 180 means the target is heading directly away from you (you are chasing his tail) not toward. 

Depends on whether you're in the USAF or the USN. In Air Force terms, 180 means straight head-on, in Navy terms, 180 means you're on the target's tail.

[Phantom711]

vor 45 Minuten schrieb Aquorys:

Depends on whether you're in the USAF or the USN. In Air Force terms, 180 means straight head-on, in Navy terms, 180 means you're on the target's tail.

Uhm yes an no…

As Tusky posted, the terms Target Aspect and Aspect Angle are both defined terms.

What you probably want to say is, that the USN usually uses TA when talking about intercept geometry whereas the USAF uses AA.

Both terms basically address the same thing: where are you laterally in relation to the other respective asset.

vor 9 Stunden schrieb Tusky:

Another way to determine an accurate aspect angle is by doing the math between your heading (also indicated on the top of the radar screen) and the target's heading (indicated on the top left of the radar screen).

NOTE: This is only true if you are pointing your nose at that target.

[Phantom711]

@bonesvf103

I don‘t know the particular document that you guys are referencing but I will definitely check it out.

However, it sounds to me, like it is at rather basic level of teaching young aviators intercepts.

For example assessing drift is rather old school from a time, when a radar contact was just a brighter greenish blob in some other green clutter. With all the data you have available now (heading, speed and of course aspect) this is not that relevant any more. 
 

As for your tactical question:

“Intercept“ is a very broad term and could mean a lot of different things in different scenarios. Initially we were talking about stern conversion intercepts where you want to roll out at a reasonably close range behind the target. As you stated correctly, this is not what you wanna try in an all out war against hostile MiGs or Suhkois…you just slam AMRAAMs into their face.

Of course this is not an answer to end all questions and it also simplifies the whole matter a bit.

[bonesvf103]

3 hours ago, Phantom711 said:

Uhm yes an no…

As Tusky posted, the terms Target Aspect and Aspect Angle are both defined terms.

What you probably want to say is, that the USN usually uses TA when talking about intercept geometry whereas the USAF uses AA.

Both terms basically address the same thing: where are you laterally in relation to the other respective asset.

NOTE: This is only true if you are pointing your nose at that target.

Yup, on my end, I was referring to it from the Navy standpoint--TA.

Manual is here:

https://www.cnatra.navy.mil/local/docs/pat-pubs/P-825.pdf

Good point on the intercept clarification...although in my usual case I'd be slamming Phoenixes in the faces!

v6,

boNes

Edited February 15, 2023 by bonesvf103