Low/High altitude transitions

[Lagrange]

I'm finding myself puzzled by the low/high altitude transition rules in TW.  I suspect I'm confusing myself, so maybe you can debug me?  I didn't see anything in errata which helped with the confusion.

On TW page 78 it says that if you are on the low altitude map and shift to altitude 11, you are removed from it at the end of your turn and end up on atmosphere row 1 of the high altitude (aka space bordering a planet) map. 

However, there is no direct mention of how to transition from the high altitude map to the low altitude map.  Do you just fly/fall into the ground row and then transition to the low altitude map at altitude 10?  That would seem logical and TW says the ground row represents the low altitude map.

But the logical thing doesn't seem to fit with the rest of the rules since TW page 80 states that the maximum velocity in the ground row of the high altitude map is 2.  Should we be thinking about velocity of units in the ground row of the high altitude map? Or just using the separate detailed velocity rules for units at low altitude?  These are different, since velocity 1 at low altitude is about 1 mapsheet per ground round implying 6 mapsheets per high altitude round.  On the other hand 1 high altitude hex is about 36 low altitude hexes.

This gets more pressing when you consider weapons fire.  If you are on the low altitude map can you fire at a unit on the high altitude map?  Logically, you should be considered simultaneously in a ground row hex on the high altitude map and on the low altitude map. 

There's further issues with the time scale variation since 6 low altitude rounds happen for every high altitude round.   Can a unit on the low altitude map fire 6 times as often at a unit on the high altitude map?  Or does targeting a unit on the high altitude map require 6 low altitude rounds?  Or does a unit in the ground row have both low altitude rounds and high altitude rounds implying it can fire 7 times per minute?

Maybe I should think of this as a "pick your poison" situation?  Either you are on the high altitude ground row map or the low altitude map (as the pilot decides) with units on different maps unable to interact with each other despite the illogic implied?  That would be conceptually simpler, but then a pilot could decide to be on the high altitude map for the high altitude turn and on the low altitude map for the low altitude turns which seems abusive?  Maybe the decision should be 'sticky' for a full high altitude turn to avoid that?  And what if there's a huge opposing ground force and a pilot simply chooses to be on the ground row of the high altitude map to avoid interacting with them?

I'm probably overthinking this, but in an invasion-from-space scenario, it seems like whether or not a unit can fire on another is a fairly important element to decide.   Similarly, can you get from point A to point B in time X could be important.

[Lagrange]

Trying to sort out the questions further:

• Is a an aerospace unit on the low altitude map simultaneously on the ground row of a corresponding high altitude map?

Assuming yes:

• If an aerospace unit on the low altitude map fires at another unit on the high altitude map via its simultaneous presence on the high altitude map, how long must it wait until being capable of firing at a unit on the low altitude map? (High altitude timescale is 6x longer then low altitude.)
• How fast can an aerospace unit in the ground row go? Velocity 1 on the low altitude map corresponds to 3 km/minute but velocity 1 on the high altitude map corresponds to 18 km/minute.

Assuming No:

• How does a unit in the ground row determine if it's on the low altitude map?
  
  • Automatically based on altitude?  But then why are there maximum velocity rules for the ground row in TW?
  • At pilots choice? But then one can avoid ground fire by declaring the ground row.  And what is the frequency with which such a decision could be changed?

Any ideas? 

[Zematus737]

You cannot fire through the interface from range 10 with heavy weapons.  Clarification for that is on page 236 of TW, as stated:

"Standard-scale weapons can fire into or out of but not through an interface hex. A unit must occupy an interface hex in order to fire at units in space and in the atmosphere. These range modifications are in addition to the to-hit penalty for firing through atmospheric hexes as shown on the Aerospace Attack Modifiers Table (see p. 237).
Only capital-scale weapons can pass through a space/atmosphere interface hex, though the range modifiers still apply."

[Lagrange]

You cannot fire through the interface from range 10 with heavy weapons.  Clarification for that is on page 236 of TW, as stated:

"Standard-scale weapons can fire into or out of but not through an interface hex. A unit must occupy an interface hex in order to fire at units in space and in the atmosphere. These range modifications are in addition to the to-hit penalty for firing through atmospheric hexes as shown on the Aerospace Attack Modifiers Table (see p. 237).
Only capital-scale weapons can pass through a space/atmosphere interface hex, though the range modifiers still apply."

There is no discussion of the interface row here.

You may be confusing the interface row with the ground row.  These are separated by 4 rows of atmosphere on the high altitude map.   Look at TW page 79 to get the picture.

[Zematus737]

Even then, there can be no interaction with the ground map units as you describe.  See page 78:
"Atmospheric movement can occur at high altitude or low altitude. High-altitude movement is effectively beyond any interaction with ground units, and so is more abstract. Low-altitude movement brings aerospace units into contact with ground units, and so the rules governing it are more complex."

in addition to that the footnote for this modifier clearly disqualifies aerospace on the ground map:
*This applies to atmospheric hexes on the high-altitude map, not to hexes on a low-altitude map, or when using Aerospace Units on Ground Mapsheets rules.

[Lagrange]

Even then, there can be no interaction with the ground map units as you describe.  See page 78:
"Atmospheric movement can occur at high altitude or low altitude. High-altitude movement is effectively beyond any interaction with ground units, and so is more abstract. Low-altitude movement brings aerospace units into contact with ground units, and so the rules governing it are more complex."

in addition to that the footnote for this modifier clearly disqualifies aerospace on the ground map:
*This applies to atmospheric hexes on the high-altitude map, not to hexes on a low-altitude map, or when using Aerospace Units on Ground Mapsheets rules.

'Ground unit" has a technical and well-defined meaning in Battletech.  It appears on TW page 20 and includes Mechs & VTOLS (amongst others), but not aerospace units which have a separate entry.  Hence, the quoted text has no influence on whether or not an aerospace unit in atmospheric row 1 can or cannot fire on an aerospace unit in ground row 1 and/or the corresponding low altitude map (or vice-versa) as none of the involved units are ground units.

Incidentally, this statement is also amended a bit by the artillery rules where ASF with artillery on the high altitude map can fire on ground hexes but are beyond return fire.

[Weirdo]

• At pilots choice? But then one can avoid ground fire by declaring the ground row.  And what is the frequency with which such a decision could be changed?

[/li]
[/list]
Any ideas?

This is correct. The pilot chooses when they're moving from Altitude 10 to the High Altitude Map. Bear in mind that popping up to High Altitude to avoid fire from the ground or Low Altitude has consequences. You are stuck with acting only once every six ground/low turns, and since most ground games rarely last more than ten turns, you're effectively conceding most of the game as far as that unit is concerned.[/list]

[Lagrange]

This is correct. Bear in mind that popping up to High Altitude to avoid fire from the ground or Low Altitude has consequences. You are stuck with acting only once every six ground/low turns, and since most ground games rarely last more than ten turns, you're effectively conceding most of the game as far as that unit is concerned.

Good.  Is this detailed anywhere? 

Also, when do you declare?

At the end of the round implies you can do a high altitude round, declare low altitude at the end, complete 6 ground rounds, and then declare high altitude in time to catch the next high altitude phase.   

At the beginning of the round implies you forgo the high altitude round and can act up to 5 times on the low altitude map before declaring high altitude again to catch the next high altitude round.

And when you declare from high altitude map to low altitude, which altitude do you end up at?  Is it always 10?  So for example an ASF could be at altitude 1, declare high altitude, be on the ground row, and then declare low altitude and be at altitude 10?

[Weirdo]

And when you declare from high altitude map to low altitude, which altitude do you end up at?  Is it always 10?  So for example an ASF could be at altitude 1, declare high altitude, be on the ground row, and then declare low altitude and be at altitude 10?

When going from High to Low, you end up at Altitude 10. Please list the page that says you can go to High straight from Altitude 1.

[Lagrange]

When going from High to Low, you end up at Altitude 10. Please list the page that says you can go to High straight from Altitude 1.

There is no page---that's just an implication of your previous claim.  In particular, if you are either on the ground row of the high altitude map or the low altitude map (but not both) as decided by the pilot then the pilot could decide to be on the ground row of the high altitude map while at altitude 1.

Apologies if I'm being dense here.   Perhaps some scenarios would be helpful.

• A pilot is at altitude 1 in their ASF and they hear over the radio that there's an incoming enemy scout ASF in the ground row of the high altitude map.  How do they fire on it?
• A pilot is on the ground row of the high altitude map in their ASF and they hear over the radio that an enemy mech has been sighted beneath them.  How do they move to Altitude 5 and bomb it?

The rules in TW that I see cover the transitions Low Altitude -> Atmospheric Row 1, Atmospheric Row 1 -> Ground Row, and Ground Row -> Atmospheric Row 1.   

There appears to be no mention of Low Altitude -> Ground Row, Ground Row -> Low Altitude, or Atmospheric Row 1 -> Low Altitude.

[Zematus737]

none of the involved units are ground units.

Activity in Low altitude and the ground map both correspond to activity on the Ground Map, and not necessarily ground units specifically.  It's hard to ignore the phrasing of the footnote that was quoted.  I include it again below.  The bottom row of the high alt map is in reference to entering this theater, which includes the low alt map.  It's Space->High alt map->low alt map (after you drop into the 'ground row')->ground map.  The ground row of the high alt map continues to be part of the high altitude map merely as a reference.  You'll see that the entire theater is included in the 0-17km envelope shown on the Re-Entry Table on page 80.

*This applies to atmospheric hexes on the high-altitude map, not to hexes on a low-altitude map, or when using Aerospace Units on Ground Mapsheets rules.  page 237 AEROSPACE ATTACK MODIFIERS TABLE

[Lagrange]

Activity in Low altitude and the ground map both correspond to activity on the Ground Map, and not necessarily ground units specifically.  It's hard to ignore the phrasing of the footnote that was quoted.  I include it again below.  The bottom row of the high alt map is in reference to entering this theater, which includes the low alt map.  It's Space->High alt map->low alt map (after you drop into the 'ground row')->ground map.  The ground row of the high alt map continues to be part of the high altitude map merely as a reference.  You'll see that the entire theater is included in the 0-17km envelope shown on the Re-Entry Table on page 80.

*This applies to atmospheric hexes on the high-altitude map, not to hexes on a low-altitude map, or when using Aerospace Units on Ground Mapsheets rules.  page 237 AEROSPACE ATTACK MODIFIERS TABLE

I believe you are claiming that you automatically transition to the low altitude map if you enter the ground row of the high altitude map?  The rules appear inconsistent with that. In your table on page 80 of TW, just look over to the next column "Max. Safe Velocity".  It lists the ground row as having a maximum safe velocity of 2 on the high altitude map.  That implies that it's certainly possible to be in the ground row on the high altitude map.  (And consequently that a unit in the ground row can fire at units in atmospheric row 1 and vice-versa.)

The footnote on page 237 doesn't seem salient to the question---a to-hit modifier does not apply at low altitude.... so what?

[Weirdo]

There is no page---that's just an implication of your previous claim.  In particular, if you are either on the ground row of the high altitude map or the low altitude map (but not both) as decided by the pilot then the pilot could decide to be on the ground row of the high altitude map while at altitude 1.

Apologies if I sound testy, but for future reference: I don't imply. I say what I said, and if my post doesn't contain certain words, I didn't say them. Thank you.

Now then: You move to high alt from Altitude 10. There. Done.

Please link the exact post where I said otherwise, so I can fix it.

[Lagrange]

Please link the exact post where I said otherwise, so I can fix it.

It's here.  I said:

...Is a an aerospace unit on the low altitude map simultaneously on the ground row of a corresponding high altitude map?... Assuming No...How does a unit in the ground row determine if it's on the low altitude map?... At pilots choice? ...

Then you said:

This is correct...

Disregarding what was said, I'd love to nail down an answer to the question.   

Are we in agreement that you are either on the low altitude map or the high altitude map, but not both?

And if so, what are the legal ways to transition between these maps?  The Low Altitude -> High Altitude transition is discussed in the rules, but not the other direction, and it seems the rules for <17km support both being in the ground row of the high altitude map and/or being on the low altitude map.

[Weirdo]

Fixed. And please note that when I said that, I narrowed down the part of your post I was quoting. I do not have answers to your entire post from memory and I'm away from my books right now, so I was responding to what I do know.

Just to make things clear, I'm going to say it again, and hopefully this time I will word it correctly:

If you are on the Low Altitude Map and want to be on the High Altitude Map, the procedure is:

1: Get to Altitude 10. This may take multiple turns.

2: Climb one Altitude level, going from Altitude 10 to Atmospheric Row 1.

There. You're done.

[Lagrange]

Yeah, Low Altitude -> Atmospheric Row 1 is covered explicitly by the rules as you state.  Atmospheric Row 1->Low Altitude seems to be implied by the reversal of this.

Atmospheric Row 1->Ground Row and Ground Row->Atmospheric Row 1 appear allowed by the high altitude movement rules. 

Ground Row <-> Low Altitude is murky.  These correspond to the same physical situation but there are no stated transition dynamics.  We could just say that this is disallowed but that seems funky given these are the same physical situation. 

[Weirdo]

That's easy. If the rulebook doesn't say you can do a thing, you can't do the thing. The whole point of game rulebooks is to be a list of the things you're allowed to do in the game. Easiest thing to do is assume that, like me, rulebooks don't imply.

[Lagrange]

That's easy. If the rulebook doesn't say you can do a thing, you can't do the thing. The whole point of game rulebooks is to be a list of the things you're allowed to do in the game. Easiest thing to do is assume that, like me, rulebooks don't imply.

I generally agree, but it seems rather incongruous if the way to get into the Ground Row from the Low Altitude map is Low Altitude -> Atmospheric Row 1 -> Ground Row.

[Zematus737]

You got it.  The only way to be in the Ground row of the high alt map is to first be in the high alt map.  The ground row is representative of a unit leaving the high alt map and entering the lower theater on the next movement turn that has the different turn phases.

From the low alt map, you rise above 10 to enter the first atmospheric row at what would otherwise be 11.  The ground row does not exist other than to signify that a unit is transitioning from one map to another, from space with 1 minute turns (every 6th turn) to the ground map rules every turn, which is 10 seconds.

The relationship of each, and their respective rules, is presented in order form highest altitude to lowest.  It can be a little confusing, but you'll notice it if you flip through it again.  The limits of velocity apply to when you are crossing the space/interface row in the high alt map.  That's why the maximum velocity table is shown with the rules for the high alt map on page 80.  There is a max velocity you can have in each row, otherwise your ship suffers damage dependent on the velocity that is over the maximum amount.

Here a phrase from TURN SEQUENCE on page 78.  Take a moment to read it over.
"Because space turns represent one minute, six atmospheric turns take place for each space turn. During play, the six atmospheric turns come first, followed by one space turn. Units moving between the space map and low-altitude map are removed from the current map at the end of their turn and enter the new map
at the beginning of the next appropriate Movement Phase. For example, a unit on the low-altitude map moves to Altitude 11 in the Movement Phase (Aerospace) of Turn 3. At the end of that
turn, it is removed from that map. It enters the space map on Row 1 of the atmosphere during the next space Movement Phase, which takes place after the sixth atmospheric turn."

Someone else will have to clarify whether you can commit to combat either way while on the ground row.  I don't know.  I use abstract maps myself and leave out the high alt map.  If it is like Battleforce, the turn sequence puts space movement AFTER ground movement on the lower scales, which means you lose the space turn combat phase in the transition during the movement phase to pick it up on the next movement phase of the respective scale turn.    Again, I hope this was helpful. 

[Lagrange]

...

So I believe the claim is that existence in the ground row is always temporary, ending with the turn.  Units in atmospheric row 1 transition to ground row, fire, and then at the end of that turn always transition to the low altitude map at altitude 10.  Furthermore, this exercises the maximum velocity entry for the ground row in the high alltitude table since movement may happen in the ground row during that transitory round.

That checks out with the text.  It has some odd effects---for example an ASF in atmosphere row 1 can transition to ground row, fire on the high altitude map, be in the low altitude map firing 6 times with the final movement be to altitude 11, and then transition to atmospheric row 1 in time for the next high altitude round.   This could be done every other high altitude round. 

[Daryk]

This discussion is becoming more confusing, not less...

[Zematus737]

So I believe the claim is that existence in the ground row is always temporary, ending with the turn.  Units in atmospheric row 1 transition to ground row, fire, and then at the end of that turn always transition to the low altitude map at altitude 10.  Furthermore, this exercises the maximum velocity entry for the ground row in the high alltitude table since movement may happen in the ground row during that transitory round.

That checks out with the text.  It has some odd effects---for example an ASF in atmosphere row 1 can transition to ground row, fire on the high altitude map, be in the low altitude map firing 6 times with the final movement be to altitude 11, and then transition to atmospheric row 1 in time for the next high altitude round.   This could be done every other high altitude round.

Everything in the 1st paragraph is solid.  You lose it on the 2nd paragraph because I used the non-existent altitude of 11 just as an example of where the High Alt map begins with Atmospheric Row 1.  You do indeed complete your combat phase once entering the ground row, and I suppose you can use any remaining movement to shift around a few hexes or even change your facing to get a last shot on someone as you ...drift?... into the Low Alt map for the next turn.  I hesitate to speak on vector movement so as not to further confound the conversation.  Anyway, the Ground row does not count as a 10 second turn space.  It is still the high alt map, you are merely declaring, by ending your movement in that row, that you are preparing to enter the low alt map on the next tactical movement turn.

[Lagrange]

This discussion is becoming more confusing, not less...

I think we're getting there...

Everything in the 1st paragraph is solid.  You lose it on the 2nd paragraph because I used the non-existent altitude of 11 just as an example of where the High Alt map begins with Atmospheric Row 1.  You do indeed complete your combat phase once entering the ground row, and I suppose you can use any remaining movement to shift around a few hexes or even change your facing to get a last shot on someone as you ...drift?... into the Low Alt map for the next turn.  I hesitate to speak on vector movement so as not to further confound the conversation.  Anyway, the Ground row does not count as a 10 second turn space.  It is still the high alt map, you are merely declaring, by ending your movement in that row, that you are preparing to enter the low alt map on the next tactical movement turn.

Altitude 11 on the low altitude map seems to exist in the same sense as the ground row on the high altitude map because the rules say: "For example, a unit on the low-altitude map moves to Altitude 11 in the Movement Phase (Aerospace) of Turn 3.  At the end of that Turn, it is removed from the map."  That implies that it exists on the map before the end of the turn. 

It also seems you can legally have an ASF skim the low/high altitude interface to participate in all space and ground turns.  For example, Space turn 1: end up in ground row, but you can still fire on other high atmosphere units because you are only removed at the end of the turn.  Ground turn 1-5 starting at altitude 10 do whatever you want at low altitude. Ground Turn 6: end up at altitude 11.  You can still fire on other units on the low altitude map because you are removed only at the end of Turn 6. Space Turn 2: start at atmospheric row 1 and move to the ground row, firing at whoever you want on the high altitude map.  Ground Turn 7-11 starting at altitude 10 do whatever you want at low altitude, Ground Turn 12 end up at altitude 11.  Repeat indefinitely.

[Weirdo]

I have to wonder exactly how often this would actually come up in game play. Seems like the kind of thing that would come up a max of...once?...every real-world decade or so.

[Lagrange]

I have to wonder exactly how often this would actually come up in game play. Seems like the kind of thing that would come up a max of...once?...every real-world decade or so.

For myself, understanding the transition structure is prerequisite to thinking about designs properly.

[Zematus737]

Sure.  That seems more reasonable than the original idea of being able to fire into high altitude units 6 times before they can get a turn to do anything about it.  I'm glad that got sorted out.