Pendraken Miniatures Forum

A couple of Visibility rule queries for clarification please -

(1) Does a ground attack aircraft (AIR:GA unit) have to have LOS to the enemy unit when concentrating attacks on it? Incidentally - does the attacking player get to select the direction of the attacking AIR:GA..and of bringing in several units at once ...could select different directions for each unit?

(2) Ref rules on p14: Think its a new rule that aircraft cannot see into HAT at all? Either way ...what if target is visible (firing) to ground troops when placed within 5cm of edge of the HAT?

(3) Can aircraft be seen through high ground? Rule on bottom of p14 says no - but think only meant to apply to not seeing through high ground crest lines?

(4) High Ground : Rules on p14 state "Units observing from high ground can see over linear terrain and into, through and over, low area terrain" - Does this also work for troops observing units on high ground?  Assume yes

(5) Line of Sight Example on p15. : This should have been updated as there are quite a few known errors - E.g. ...

(i) Unit A does have LoS to the KV-1 among the buildings - as can see through 10cm of intervening HAT. I believe it also has LoS to the Russian infantry unit on the far right of the hill, unless the intervening HAT terrain is >5cm in depth, or infantry are deemed to be on the crest line (doubtful, as orientation of units B,C & D are basically the same as A...and they can see the infantry fine in the example). This as rules on p12 state that hills are higher than all other terrain pieces (except mountains)

(ii) Unit B does have LoS to the same Russian infantry unit on the hill as unit A (per above rationale)

(iii) Unit D : does have LoS to the Russian infantry adjacent to the hedge - unless this is deemed to be more than 10am between the two units. It definitely can see the KV-1 on the road

Many thanks for the help here!

Answers in bold inserted below:

(1) Does a ground attack aircraft (AIR:GA unit) have to have LOS to the enemy unit when concentrating attacks on it? Incidentally - does the attacking player get to select the direction of the attacking AIR:GA..and of bringing in several units at once ...could select different directions for each unit?

> Yes - LoS is required to concentrate attacks
> Yes - the attacking player selects the direction of the air attack, although it is irrelevant as all AA fire is calculated at the final point that the attacking aircraft end up at to deliver their attack.
> No - if (for example) 3 aircraft are called in on a single order they must all end up together (if a clarification is required for this then the flight must be within 5cm of each other). If the aircraft come in using different orders they can come in from any direction and be placed away from each other.

(2) Ref rules on p14: Think its a new rule that aircraft cannot see into HAT at all? Either way ...what if target is visible (firing) to ground troops when placed within 5cm of edge of the HAT?

> it doesn't matter - the principle is that aircraft cannot be ordered in by anybody other than Commanders. There is no ground to air communication - despite what Hollywood might have us believe! By HAT - this applies specifically to BUAs and Woods, Forests etc. Aircraft cannot see individual units in an HAT (NB: you can be on a hill, not in a hill)

(3) Can aircraft be seen through high ground? Rule on bottom of p14 says no - but think only meant to apply to not seeing through high ground crest lines?

> Nothing sees through High Ground to aircraft ... aircraft are above the high ground so can see down onto it and be seen above it.
NB: I am not going to start getting drawn into a situation where we start discussing the height of flight stands v the actual height of model hills  :)

(4) High Ground : Rules on p14 state "Units observing from high ground can see over linear terrain and into, through and over, low area terrain" - Does this also work for troops observing units on high ground?  Assume yes

> No -  It all depends - do they have a LOS to the unit. If NO (they are behind a crest or a BUA or a Wood or even a hedge or wall on the hill) they cannot be seen from below.
If the Unit is on the High Ground facing the enemy below and are not screened by any of the above or any other conceivable obstacle (such as the Sorpe Dam ... for example  :D) and there is a clear LOS from the unit below, then the answer is YES, they can be seen.

(5) Line of Sight Example on p15. : This should have been updated as there are quite a few known errors - E.g. ... (Maybe ... but let's work through them)

(i) Unit A does have LoS to the KV-1 among the buildings as can see through 10cm of intervening HAT.
> we could be more specific about distances maybe - or better define the actual area of the BUA, however - the key point is on Page 14 - that LoS is blocked by intervening HAT. And the decriptor at the bottom of page 15 states:
" ... the High Area Terrain lies between the two units". Admittedly the text above states that the KV1 is "amongst' the buildings ... but the intention is/was that the KV1 is on the far side of the BUA.

I believe it also has LoS to the Russian infantry unit on the far right of the hill, unless the intervening HAT terrain is >5cm in depth, or infantry are deemed to be on the crest line (doubtful, as orientation of units B,C & D are basically the same as A...and they can see the infantry fine in the example). This as rules on p12 state that hills are higher than all other terrain pieces (except mountains).
> The issue is none of the above - it is because the Infantry unit is on the far reverse slope of the Hill. It's neighbor on the right is visible on the crest.
NB: I generally would rule that if a BUA or a Wood is nearer to the observer unit, than its target, the nearer HAT blocks line of sight. I've stood looking up at a mountain with a wood in front of me and cannot see the mountain behind it. But again, we need to adopt some sensible thinking here. In the example if you draw a LoS from any of the German units to the far Russian Infantry it will pass through the Wood anyway and the wood is also at least 5cm deep.

(ii) Unit B does have LoS to the same Russian infantry unit on the hill as unit A (per above rationale)
> nope - on the same basis as above

(iii) Unit D : does have LoS to the Russian infantry adjacent to the hedge - unless this is deemed to be more than 10cm between the two units. It definitely can see the KV-1 on the road
> Unit D cannot see the infantry adjacent to the hedge because of the intervening Low Area terrain - as per P14 - and again we are assuming there is 10cm of Low Area crops in the field. It can of course see the KV1 on the road.

Could the example be a lot more specific ... probably maybe or yes ...  but it doesn't have to cover all eventualities as the main rules text is what matters.

Interesting - Thanks Mark.
Points in blue below...

1) Does a ground attack aircraft (AIR:GA unit) have to have LOS to the enemy unit when concentrating attacks on it? Incidentally - does the attacking player get to select the direction of the attacking AIR:GA..and of bringing in several units at once ...could select different directions for each unit?

> Yes - LoS is required to concentrate attacks
> Yes - the attacking player selects the direction of the air attack, although it is irrelevant as all AA fire is calculated at the final point that the attacking aircraft end up at to deliver their attack.
> No - if (for example) 3 aircraft are called in on a single order they must all end up together (if a clarification is required for this then the flight must be within 5cm of each other). If the aircraft come in using different orders they can come in from any direction and be placed away from each other.


Very helpful. All fire-zones will be the same area if ordered at the same time.


(2) Ref rules on p14: Think its a new rule that aircraft cannot see into HAT at all? Either way ...what if target is visible (firing) to ground troops when placed within 5cm of edge of the HAT?

> it doesn't matter - the principle is that aircraft cannot be ordered in by anybody other than Commanders. There is no ground to air communication - despite what Hollywood might have us believe! By HAT - this applies specifically to BUAs and Woods, Forests etc. Aircraft cannot see individual units in an HAT (NB: you can be on a hill, not in a hill)

Sorry - I was not clear. Thinking whether the aircraft could see into 5 cm of edge of HAT to attack because the FAC could see the target there?

(3) Can aircraft be seen through high ground? Rule on bottom of p14 says no - but think only meant to apply to not seeing through high ground crest lines?

> Nothing sees through High Ground to aircraft ... aircraft are above the high ground so can see down onto it and be seen above it.
NB: I am not going to start getting drawn into a situation where we start discussing the height of flight stands v the actual height of model hills   

Sorry - Again Im not being clear. Example -  Player 1's AA unit located 10 cm West of hill...Player 2's aircraft comes in successfully to attack Player 1's other units exposed on hill. I think the AA unit can get LoS to the Aircraft and not be blocked by the hill  - unless the aircraft is on the opposite side of the crest. If its on the West side of the hill ..it's visible to the AA? 

(4) High Ground : Rules on p14 state "Units observing from high ground can see over linear terrain and into, through and over, low area terrain" - Does this also work for troops observing units on high ground?  Assume yes

> No -  It all depends - do they have a LOS to the unit. If NO (they are behind a crest or a BUA or a Wood or even a hedge or wall on the hill) they cannot be seen from below.
If the Unit is on the High Ground facing the enemy below and are not screened by any of the above or any other conceivable obstacle (such as the Sorpe Dam ... for example  ) and there is a clear LOS from the unit below, then the answer is YES, they can be seen.

Of course yes - thanks

(5) Line of Sight Example on p15. : This should have been updated as there are quite a few known errors - E.g. ... (Maybe ... but let's work through them)

(i) Unit A does have LoS to the KV-1 among the buildings as can see through 10cm of intervening HAT.
> we could be more specific about distances maybe - or better define the actual area of the BUA, however - the key point is on Page 14 - that LoS is blocked by intervening HAT. And the decriptor at the bottom of page 15 states:
" ... the High Area Terrain lies between the two units". Admittedly the text above states that the KV1 is "amongst' the buildings ... but the intention is/was that the KV1 is on the far side of the BUA.

Ah - very interesting. Had always interpreted that as LoS is limited to 5cm into, through or out of HAT as a minimum (p14 HAT rule)...that this meant units could gain LoS through up to 5cm of intervening HAT. More than 5cm of intervening HAT needed to block LoS. Hence in the Example ..there is hardly any HAT base between Unit A and the KV-1 in question...and so KV-1 can be seen

I believe it also has LoS to the Russian infantry unit on the far right of the hill, unless the intervening HAT terrain is >5cm in depth, or infantry are deemed to be on the crest line (doubtful, as orientation of units B,C & D are basically the same as A...and they can see the infantry fine in the example). This as rules on p12 state that hills are higher than all other terrain pieces (except mountains).
> The issue is none of the above - it is because the Infantry unit is on the far reverse slope of the Hill. It's neighbor on the right is visible on the crest.

Yes - Im talking about that infantry unit too. However - that infantry on the crest would only be visible if firing ..otherwise, as infantry have Low Profile...they can only be seen if enemy unit is within 10cm (per rule on p14) no? So I am assuming not on crest...but this unit would still be visible if the intervening woods are not >5cm wide no?


NB: I generally would rule that if a BUA or a Wood is nearer to the observer unit, than its target, the nearer HAT blocks line of sight. I've stood looking up at a mountain with a wood in front of me and cannot see the mountain behind it.


Interesting point. Had not thought about that one before. This is why so important to sort out terrain impacts before start of any game! I was simply going with the rule on p12 that hills are higher than all other terrain (save mountains)   

But again, we need to adopt some sensible thinking here. In the example if you draw a LoS from any of the German units to the far Russian Infantry it will pass through the Wood anyway and the wood is also at least 5cm deep.

(ii) Unit B does have LoS to the same Russian infantry unit on the hill as unit A (per above rationale)
> nope - on the same basis as above

(iii) Unit D : does have LoS to the Russian infantry adjacent to the hedge - unless this is deemed to be more than 10cm between the two units. It definitely can see the KV-1 on the road
> Unit D cannot see the infantry adjacent to the hedge because of the intervening Low Area terrain - as per P14 - and again we are assuming there is 10cm of Low Area crops in the field. It can of course see the KV1 on the road. 
Good -yes. We are saying the same thing here

Could the example be a lot more specific ... probably maybe or yes ...  but it doesn't have to cover all eventualities as the main rules text is what matters.

Hmmmm. I think the Example should be there to be clear on all LoSs. and explain the multitude of text options. That's the whole point and hence why think it would have been helpful to revise when doing the update from BKCII

Attempt to respond ....

"Very helpful. All fire-zones will be the same area if ordered at the same time."
Yes. If you call in 3 aircraft in one strike - all 3 hit the same fire zone - so are all part of the same attack. Therefore all 3 attack dice are combined. Just the same way an Artillery Concentration works.

"Sorry - I was not clear. Thinking whether the aircraft could see into 5 cm of edge of HAT to attack because the FAC could see the target there?"
P14 - High Area Terrain - last sentence "...Aircraft cannot see through high area terrain (and cannot see into high area terrain).

However, I agree that as it is the FAC that is locating the target, so long as it is within 5cm of edge of the HAT it can be targeted. 
If, however, it was an FAO/FAC in an aircraft (potentially possible in a scenario) it would not apply.

Sorry - Again Im not being clear. Example -  Player 1's AA unit located 10 cm West of hill...Player 2's aircraft comes in successfully to attack Player 1's other units exposed on hill. I think the AA unit can get LoS to the Aircraft and not be blocked by the hill  - unless the aircraft is on the opposite side of the crest. If its on the West side of the hill ..it's visible to the AA?

The Aircraft are considered above the hill - the crest is irrelevant. To conduct an Airstrike you place the aircraft model/unit on the table. It can be placed out of range of enemy AA units on the ground (but there cannot be any measuring to achieve this) but it will be subject to AA fire from all AA within range.
This might at first seem illogical - as in your example the aircraft might be flying low deliberately - however - at some point it is assumed that the aircraft will come into LoS of the AA (as it passes over the hill after its attack).
It is a mechanism to ensure a quick resolution to an airstrike and avoid situations where pilots are played as if they are omnipotent and know the exact LoS or ranges or location of all enemy AA on the table and can weave a path to avoid being shot at.

Ah - very interesting. Had always interpreted that as LoS is limited to 5cm into, through or out of HAT as a minimum (p14 HAT rule)...that this meant units could gain LoS through up to 5cm of intervening HAT. More than 5cm of intervening HAT needed to block LoS. Hence in the Example ..there is hardly any HAT base between Unit A and the KV-1 in question...and so KV-1 can be seen.

"Thorough" in this instance means into rather than out the other side. So if a BUA or a Wood is more than 5cm wide units cannot be seen on the other side of it.
With regards to the Example - you are being too literal. The area of the BUA encompasses all 3 houses. The distance between Unit A and the KV1 is assumed to be over 5cm.

Yes - Im talking about that infantry unit too. However - that infantry on the crest would only be visible if firing ..otherwise, as infantry have Low Profile...they can only be seen if enemy unit is within 10cm (per rule on p14) no? So I am assuming not on crest...but this unit would still be visible if the intervening woods are not >5cm wide no?

Again - the assumption is that the wood is at least 5cm wide. The Infantry on the right (nearest the germans) are indeed low profile and so we shall assume that they have fired - I'll ensure that this is added to the errata.

Interesting point. Had not thought about that one before. This is why so important to sort out terrain impacts before start of any game! I was simply going with the rule on p12 that hills are higher than all other terrain (save mountains).

Some sets of rules work on pre-set 'shadows or blind spots' behind a terrain piece - others work on a physical LoS (so you actually run a tape measure or straight edge from the unit on the higher terrain over the top of the intervening terrain to the enemy target unit. If this line passes through the intervening terrain, the LoS is blocked. Either is a way to work - if you want to work at that level of detail. But you always end up with exceptions - Snipers in church bell towers are the much used example - how far and what can the sniper see, and what can they shoot over, as a bell tower is often higher than most surrounding buildings or woods.
I could introduce a 'shadow' rule that states that any unit behind a HAT and within 10cm of HAT is considered to out of sight. If that works for you then by all means please use it.

We will look at making the LoS example clearer.
Thanks
Mark

Quote from: Big Insect on 26 May 2019, 09:06:23 AM
Attempt to respond ....

"Very helpful. All fire-zones will be the same area if ordered at the same time."
Yes. If you call in 3 aircraft in one strike - all 3 hit the same fire zone - so are all part of the same attack. Therefore all 3 attack dice are combined. Just the same way an Artillery Concentration works.

But each aircraft deviates separately right - like with an arty concentration - The only "combining" is if something happens to be in a patch where they overlap?

It is a change from BKCII for Requested Air Support.

In BKCII - Requested Artillery all had to fire at the same target (p26)...the same in the BKCIV (p47).
In BKCII - Requested Air Support could strike at different targets (p28) ....BKCIV has "All requested units fire at the same target" (p51).

So now with Requested Air Support - only 1 deviation roll per order from each FAC - and all successfully brought-in fire-zones will overlap - the Player may then choose whether to Concentrate such attacks onto a single target unit..to which the aircraft must have LoS.

Clarification is needed if such attacks are considered 'Direct Fring' for other rule modifiers - E.g. the new Low Profile -1d6 attack dice.

AJ

Yes ... it is a change from BCKII - it is to make the 2 mechanisms as closely comparable as possible.

It was also deemed to be unrealistic that a flight of aircraft could be called in by a single FAC and then end up all over the place. The FAC is calling in an attack on a target and is looking for a concentration of fire and generally that is what happens. Worth looking at footage of Typhoons shooting up a German supply train to see the effect desired.

Interestingly, this approach was already the way that most of the play-testers were already playing it and when the actual rules were spelled out to them, many just scoffed at how daft that was.

Why are you saying Air Attacks are considered Direct Attacks?
There is nothing in the rules to say they are (are there?) ... LoS is needed from the point of attack but the attacks are coming in from above (even if they are cannon or MG fire)

Back to original questions  -

(3) Clearly im being thick.....but rule on bottom of p14 says "Aircraft cannot be seen through High Ground."  This was the same in BKCII.
I am checking whether High Ground in fact only means Crest Lines as it was in v2.
Am trying to follow your previous comments logic ...but this would seem to say that Aircraft CAN be seen through High Ground (as flying above the hill) ?


(5i) Err - Respectfully disagree.
Unit A can see into, through or out of 10cm of BUA (as both units have Average profiles).
Given that Unit B can see the KV-1 ....why not Unit A.

Its just a sloppy Example - always was.

V glad you are  looking at making clearer  :)

3).
Aircraft cannot be seen through High Ground ... correct ... but we are back to the issue about how high is the aircraft off the table top when it makes its attack. And as I have said, that is not an area or direction I am intending to go into or debate.

If you have a friendly 'target' unit on the far side of a Mountain from a friendly AA unit, and the strike point of the attacking enemy aircraft is also on the far side of the mountain, then the AA clearly cannot see 'through' the High Ground (the Mountain). If the target friendly unit is on the crest of the mountain, and the attacking aircraft is on the far side, again the AA cannot shoot at that aircraft. However, if the aircraft is on the far side of the Mountains and dives to make it's attack from 20,000 feet it might (depending upon the height of the Mountain) be visible to the AA and if the AA has the range it can shoot at the Aircraft.

There is no provision for the flight path of aircraft on table making an attack. That is deliberate, as it adds huge complexity to something that is actually quite simple.
In most games we are not talking about Mountains, we are talking about BUAs or Low rises or hillock or Woods. Aircraft rarely fly low enough to be hidden from view behind these or even by a High Area Terrain piece like an on-table hill.
Even if the AA unit is within 5cm of a Wood and the strike point of the aircraft is 30cm behind the wood, it is assumed that at some point the aircraft will either fly over the AA gun or fliy into sight. It is all just a gaming mechanism ... not an actual simulation of real life.

So, in reality in a normal game Aircraft are to be considers as flying higher than high ground, as is mostly the case in reality. Therefore, the Crest Line is an irrelevance here.
You might need to accept Adam that no set of rules is going to cover every eventually or necessarily work exactly as you expect it to.

5).
Yes - but Average to Average is an irrelevance it also clearly states that the KV1 is on the other side of the Village - so cannot be seen.
The fact that the photograph has been set up to look nice/pleasing - so doesn't have a visible template area for the BUA area - is clearly causing this concern. Nowhere in the description does it talk about the depth of the BUA or the Woods or how far any unit is from each other. It's a general example. The wording in the rules is clear on all these matters.
However, you do clearly understand the rule here and the intention of the rule. So that's OK.

Cheers
Mark

I have also stated we will 'clean up' the descriptions.

Thanks again for your patience on finishing off this one -

Still confused on point (3) ref Aircraft not being seen through High Ground - sorry...have asked around - but no joy.

Essentially checking whether V4 is different to V2 - where (per FAQ sheet ...Question number 10) -
Question : "How does terrain affect anti-aircraft fire? "
Answer : "Anti-aircraft and command units may not fire at aircraft if either high area terrain or high ground lies between the anti-aircraft/command unit and the target aircraft.
If an anti-aircraft or command unit is inside high area terrain, or behind the crest line of high ground in relation to the aircraft, then it may not fire at the aircraft."

May I Ask if you can help clarify if still works like this please?
Thanks again
Adam

I respond as previously AJ

Ground Attack Aircraft do not have a line of attack or flight path in BKC - they are placed on-table once the attack is finalized. So are deemed to he visible at some point during their attack runs. As a game-play mechanism as we do not want to have to put flight paths into the rules around this point - they are deemed to be visible to AA at the point they make their attack.
As aircraft generally fly above the height of hills (as we define Hill in a table top game) and certainly above the height of Woods and BUAs, they are visible to all AA within range, LoS and LoF.

But if you are looking for a definite ruling you are not going to get one from me I'm afraid, as it all depends how you define your terrain on table.
However, if you have very high 'hills' defined in your game, then the aircraft behind these very high hills would not be within LoS of AA or Command units AA.

I was lucky enough a few weeks back to be in a hot air balloon at 1,000 metres at 05.30 above Sienna in Tuscany. What I'd observe is that what were reasonable hills when I was on the ground driving to the balloon launch site, were totally irrelevant to LoS once we were in the air. In fact even at 500 metres LoS was not really effected. What I expected to be blind spots behind buildings or woods disappeared.
The only blind spot I observed was when we were at c.200 metres or below and had there been an AA on the other side of Sienna it wouldnt have seen us to shoot but TBF if I was an aircraft I'd have been shielded from AA an incredibly short period of time and even if I'd flown at Sienna (in the blind spot) I would have become visible at some point in my attack run.

So ... I'll ask a question back ... what specific scenario is this question in relation too AJ? Give me something to work with please and I will try and help you.

Thanks
Mark

Thanks Mark - v much appreciated -

I'll try with the following examples -

Scenario 1 :
- Player 1's AA unit (with 30cm AA range) is on-table, 10cm West of a piece of HAT (a small wood 10cm wide)
- Player 2's Aircraft unit is requested via FAC to attack enemy units East of the wood
- After testing for deviation - the Hit point of the air attack ends up 5cm East of the wood
- Now the AA unit is 25cm away from the air Hit point on the other side of HAT.
- Because the AA unit needs LoS to the Hit Point to fire AA - It cannot attack the aircraft. Believe this is correct?

Scenario 2 :
- Player 1's AA unit (Let say a Flak 30/38, with 40cm AA range) is on-table, 5cm inside (from the Eastern edge) a piece of HAT (a small BUA 20cm wide)
- Player 2's Aircraft unit is requested via FAC to attack enemy units East of the BAU
- After testing for deviation - the Hit point of the air attack ends up 5cm East of the BAU
- Now the AA unit is 10cm away from the air Hit point
- Can the AA unit attack the aircraft or be the aircraft's concentration attack target (needing LoS)?
- Rule on p14 says Aircraft cannot be seen through HAT..and cannot see into HAT.
- So believe neither AA or aircraft have LoS?
In BKCII ...the Visibility rule was only that 'Aircraft cannot be seen through HAT'. This allowed aircraft to see into HAT ...but not be seen by units inside HAT.
Lack of visibility to the aircraft was also confirmed in the FAQ ..."If an anti-aircraft or command unit is inside high area terrain, or behind the crest line of high ground in relation to the aircraft, then it may not fire at the aircraft."

Scenario 3 :
Per Scenario 2 - but AA unit now on Eastern edge of BAU (facing East) - Does this make a difference? Its still in the HAT

Scenario 4 :
- Player 1's AA unit (with 30cm AA range) is on-table, placed on a piece of High Ground (a small hill 20cm wide), 5cm from the Western edge
- Player 2's Aircraft unit is requested via FAC to attack enemy units East of the hill
- After testing for deviation - the Hit point of the air attack ends up on the hill, 5cm from the Eastern edge (behind the crest line in relation to the AA unit)
- Can the AA unit fire at the aircraft? Believe it cannot because on other side of crest?

Scenario 5 :
As per Scenario 4...but the Hit point of the air attack now deviates further, and ends up only 2cm from the AA unit ...on the Western side of the hill.
Can the AA unit now fire at the aircraft? We believe it can.
Or....per p14 rule....'Aircraft cannot be seen through High Ground'....so even 2 cms blocks LoS? That doesnt sound right to us.

Answers in Bold:

Scenario 1 :
- Player 1's AA unit (with 30cm AA range) is on-table, 10cm West of a piece of HAT (a small wood 10cm wide)
- Player 2's Aircraft unit is requested via FAC to attack enemy units East of the wood
- After testing for deviation - the Hit point of the air attack ends up 5cm East of the wood
- Now the AA unit is 25cm away from the air Hit point on the other side of HAT.
- Because the AA unit needs LoS to the Hit Point to fire AA - It cannot attack the aircraft. Believe this is correct?

Incorrect - how high is the aircraft flying? (don't answer ... it is irrelevant) You are making the assumption that the Hit point is where the aircraft is. If the Aircraft is 5cm from the small wood it will a. either crash into it if it flies straight at the wood - or b. fly over or past the wood at some point in it's flight path so will be subject to the AA fire

Scenario 2 :
- Player 1's AA unit (Let say a Flak 30/38, with 40cm AA range) is on-table, 5cm inside (from the Eastern edge) a piece of HAT (a small BUA 20cm wide)
- Player 2's Aircraft unit is requested via FAC to attack enemy units East of the BAU
- After testing for deviation - the Hit point of the air attack ends up 5cm East of the BAU
- Now the AA unit is 10cm away from the air Hit point
- Can the AA unit attack the aircraft or be the aircraft's concentration attack target (needing LoS)?
- Rule on p14 says Aircraft cannot be seen through HAT..and cannot see into HAT.
- So believe neither AA or aircraft have LoS?
In BKCII ...the Visibility rule was only that 'Aircraft cannot be seen through HAT'. This allowed aircraft to see into HAT ...but not be seen by units inside HAT.
Lack of visibility to the aircraft was also confirmed in the FAQ ..."If an anti-aircraft or command unit is inside high area terrain, or behind the crest line of high ground in relation to the aircraft, then it may not fire at the aircraft."

The AA inside the HAT cannot shoot out
Forget BKCII here.

Scenario 3 :
Per Scenario 2 - but AA unit now on Eastern edge of BAU (facing East) - Does this make a difference? Its still in the HAT

As above the AA is inside the HAT

Scenario 4 :
- Player 1's AA unit (with 30cm AA range) is on-table, placed on a piece of High Ground (a small hill 20cm wide), 5cm from the Western edge
- Player 2's Aircraft unit is requested via FAC to attack enemy units East of the hill
- After testing for deviation - the Hit point of the air attack ends up on the hill, 5cm from the Eastern edge (behind the crest line in relation to the AA unit)
- Can the AA unit fire at the aircraft? Believe it cannot because on other side of crest?

Again - the crest is irrelevant - you are taking things far too literally AJ  :) - think about it in real life, how can the aircraft possibly strike that close to the AA without being seen? It might fly low but at some point it will be visible to the AA & fired upon. The strike point is just that - the place the attack lands. It is used as a nominal location point for AA fire as a games mechanism.

Scenario 5 :
As per Scenario 4...but the Hit point of the air attack now deviates further, and ends up only 2cm from the AA unit ...on the Western side of the hill.
Can the AA unit now fire at the aircraft? We believe it can.
Or....per p14 rule....'Aircraft cannot be seen through High Ground'....so even 2 cms blocks LoS? That doesnt sound right to us.

Again, you are all being far too literal - "Aircraft cannot be seen through High Ground" really only applies to Mountains or very high hills. In an ordinary game situation most hills are not high enough to stop AA shooting at an attacking aircraft.
As previously stated - the strike point is not the aircraft - it is the point the attack is occuring - it is used as a 'nominal' position for the aircraft to be at for AA fire, but it is not on the ground at that point but in the air above it or on an angle to shoot at it. But the rules are not designed to have aircraft models on stands that represent the altitude they are flying at to make an attack.

Cheers
Mark

Page 8 - sentence just under the top table - Profile
"Air units do not have a profile. They can see and be seen from anywhere on the ground, except where the ground troops are in a certain type of terrain see (Visibility Page - Page 14) for exceptions.

Page 14 - Line of Sight .... Line of sight is blocked by any of the following: Intervening high area terrain, high ground and smoke screens.
(NB: this is really aimed at ground troops to ground troops not Ground to Air or Air to Ground ... I will clarify)

Page 14 - High Area Terrain ... Aircraft cannot be seen through high area terrain (and cannot see into high area terrain).
See comments below

Page 14 - High Ground ... Aircraft cannot be seen through high ground
See comments below

Page 52 - Anti-Aircraft Fire ....
Once the hit point has been determined, the following units may use anti-aircraft fire against each aircraft unit:

• any unsuppressed and deployed AA unit within range and LOS of the Hit Point ...
• any unsuppressed command unit with AA capability within range and line of sight of the Hit point

*To clarify things AJ - I will amend the above in the errata. To indicate that in most circumstances an Air strike can be hit from anywhere on the table. If it is on the other side of a Mountain
then it cannot be hit ... but let's not get into the whole business of crest-lines on mountains please !!!

NB: checking on the inter-web I found this:
An Attempt to Define the Height of a Mountain.
According to the USGS, up until the 1920's the British Ordnance Survey defined a mountain as a geographic feature rising higher than 1000 feet (304 meters). The United States followed suit and defined a mountain as having a local relief higher than 1000 feet. This definition, however, was dropped in the late 1970's.
Nowadays, the Ordnance Survey defers to local customs and traditions but generally defines a mountain as having a minimum height of 610 meters or 2,000 feet (with the availability of high precision GPS equipment, some have taken to remeasuring British mountains in an effort to get previously designated hills reclassified as mountains).

To be frank, unless you have AA units in large parks in cities or towns, or on top of buildings - shooting up out of a BUA is really difficult.
Likewise ... going back to my balloon ride in Tuscany, we were floating so low over a piece of woodland at one point, that we were able to pluck leaves from the top-most branches of the trees, but we could see nothing below the canopy. Just hear the sound of wild boar grunting and squeaking below us.
:D

Ah - I see...your explanations make much more sense now - thank you ..

Hopefully the summary below gets this right? -

In BKCII, AA firing required LoS to the post-deviation Hit Point - this was the notional AA target point for the aircraft - and it was at ground level...(per rule now on p52 and clarified in the old FAQ..answer 10) -
this was how intervening HAT or hill crests used to block LoS for AA.

In BKCIV - this is being updated.....It's the intention that AA should not be so restricted.

The LOS needed for AA fire, is now to the air space above the ground level Hit Point - and will not be blocked by anything except mountains (or very high ground) designated at the start of the game.
The Hit Point on the ground is now only for measuring AA range.

Further - Aircraft can neither be seen, or see, units inside HAT (unless in open areas in the HAT e.g. a large clearing in a wood, or a town square/park - to be designated at the start of the game). This includes units on the edge of HAT.

In the hope this is right - thank you in advance.
It toook some time - but we got there!
Adam

Yes ... you've got it.
Cheers
Mark