SAS is predominantly a strategic and operational simulation. Nevertheless, very important tactical play is also supported.
During turn calculation, amendments to the plans you made in the deployment stage are often necessary - the unfolding situation will present many threats and opportunities requiring deviations of fleet courses and speeds, and often, the early return to base of damaged ships. Targets for air strikes will frequently present themslves, requiring almost constant evaluation of priorities.
SAS gives you a very large range of options for rolling up your sleeves and making tactical decisions during turn calculation - but only to the extent you want.
You can have varying levels of both direct and indirect control over changes of fleet movements during calculation.
The simplest and quickest level of control is reactive control - you selectively review and amend your 2IC's changes of orders when he makes them. Just nominate any of your fleets for your own attention. You will then be advised whenever your 2IC wants to change their orders. The changes are simplified as responses to known enemy threats and opportunities: your fleets will want either to deviate to avoid the enemy, or to intercept or shadow him. You will see pop-up dialogs asking you to confirm (or change) these orders.
Sometimes, your 2IC needs to send ships prematurely back to base - eg because they are too damaged, or low on fuel. If enough important ships need to return, the whole mission may need aborting. You can also get involved in these decisions for selected fleets. You will be advised whenever ship departures are recommended, and then you can amend your 2IC's orders as necessary.
In addition, if you really want to get into the thick of things, you can exercise proactive control - just pause the calculation at any point, review the relative status and location of your feets and the enemy's and then initiate new movement orders - either the hard way, by re-plotting courses and speeds yourself, or more simply and quickly - by nominating new general orders (such as fleet A to intercept enemy fleet B) which your 2IC then turns into new detailed course and speed instructions.
Each of your fleets has default rules of engagement (RoE) appropriate to the type of mission. The RoE dictate how eager the fleet will be to enter a battle, and to remain in combat, given the enemy's strength. The RoE also control the aggressiveness of individual ships - the priority they put on self preservation vs attacking the enemy.
Though you cannnot (as yet) command any ships in a battle once it has started, you can ensure that the behaviour of your fleets and ships meets your expectations by amending the RoE for any fleets - at any time. You can do this in the deployment phase, as well as at any time during calculation (by pausing the calculation and selecting a fleet for a change of RoE).
RoE are a simple and effective way of getting your fleets to fight at the tactical level in the way that accords with your operational and strategic goals. For example, as the German player, you can send raiders like the Graf Spee on historically-based missions with orders to avoid combat with equal or superior enemy, and to engage from safe distances. Or you can take the bull by the horns and give much more aggressive orders - the choice is yours.
More than any other facet of combat operations, the launching of air strikes requires the greatest level of attention because new threats and opportunities constantly present themselves, and there are many factors to consider.
SAS has taken all the pain out of this very complex area of command by automating it all for you. But it also allows you almost complete freedom to review and amend the decisions made for you - at any time during calculation. New features introduced in ver 1.1 give unprecedented flexibility of control.
At a general level, you can proactively change any of a large number of policy preferences used by your 2IC when creating strikes. These preferences affect which enemy fleets and ports are targeted, how many bombers and fighters are sent and from where, how bombloads are set, how many aircraft are retained for defensive combat air patrols, and much more.
Additionally, you can select any carriers or airfields for closer control and can view and amend the targetting and strike profile for strikes as they are being formed up, or simply abort them or order the airfield or carrier to hold back from launching strikes until further notice.
The help file on how to set rules of engagement covers this important area. You can do this at any time - during planning as well as during turn calculation.
Other tactical play options are all available from the Run Turn screen, i.e. while the turn is being calculated. See tactical responses for an overview of tactical play functions available during calculation.
A PBEM game is typically played on physically separate computers. Each player runs their turn calculation separately. Yet the calculation MUST guarantee that the results are the same for both, otherwise the game would quickly get 'out-of-synch'.
The tactical play options mentioned above that can occur during turn calculation are designed for play-against-the computer mode and are automatically disabled in PBEM games.