[Wyvern]

Moving on from chapter 2 to chapter 3:

Threat ranges that are less than the current grid size are treated as zero. This means that characters aboard a vessel will be able to make melee attacks of opportunity against vessels in their own square.
You need to make this latter point clear in the chapter itself. Otherwise, people are likely to interpret a threat range of zero as no threat range.

...if the character makes a melee attack against a target that is not moving in parallel to her vessel, she applies the Charge bonus to her attack roll and suffers the Charge penalty to her AC against any similar.
I really don't see the purpose of this rule. The rules for charging in the PHB are intended to simulate a specific situation, which is not applicable in aerial combat. A fighter standing on the deck of an airship and whacking at another airship with his sword as it passes within reach isn't charging. Also, the rules for dive attacks already cover the closest analagous situation.

When using a guided weapon, the opterator makes a ranged touch attack... ignoring any armour bonus, shield bonus or natural armor bonus.
When you say "shield bonus", I assume you're referring only to physical shields and not magical or technological force fields, right?

The loss of hit points may be stopped by a successful Repair check (DC 15), but the vessel remains disabled.
This brings up the issue of whether to include a Repair skill. BlackJaw was in favor of using the Craft skill to cover repairs, and I conceded the point, but now you're adding the Repair skill back in. We need to come to a consensus on this.

When a vessel's hit points drop to -10 or lower, it is immediately destroyed and begins to spiral. The pilot cannot use the Regain Control stunt in order to stop the spiral as the vessel is too damaged to respond to her efforts.
You need to update this to remove references to spiraling and the Regain Control stunt.

Vessels always ignore subdual damage.
I think this should read "vehicles" (since flying creatures aren't immune to subdual damage).

On a related note, are you plannning on treating vehicles as objects in the sense that they only take half damage from energy attacks and personal ranged weapons?

It is possible to direct attacks specifically against a weapon or other feature on a vessel.
I'd recommend changing "feature" to "component" in this sentence and the ones following.

The feature uses its own size modifier. Damage taken by a feature is not applied to the total damage taken by the vessel.
Does this mean that BlackJaw is going to have to include size and hit points in his component descriptions? What about components that are spread througout a vehicle (such as life support)?

It is not possible for vessels to bull rush each other, but any pilot may attempt a ramming attack.... She chooses a single vessel in that square and makes a Piloting skill check against that vessel's AC.
Shouldn't this be touch AC? If armor doesn't protect you against an accidental collision, it shouldn't protect you against a deliberate one either.

Somewhere in here we need to include rules for critical hits on vehicles (since we all seem to agree that they should be vulnerable to them). A chart of possible effects would be more interesting than just applying extra damage. We also need to address the effects of a hull breach in water or vacuum, and what might cause one (e.g. crash-landing, critical hit, limpet mine, piercing ram, going to negative hit points).

Wyvern