This timer was introduced by CCP as a way of making sure that your client and server are in-sync as to where your character is located. Events that trigger session change timer:
Examples of session change timer messages:
Once you enable the session change timer, you will see it as a small rolling ball located on the upper left hand side corner. If you drag your mouse over it, it will tell you how many seconds it has left.
Being unaware of the session change timer often gets ships killed.
After jumping through a gate, your ship will get a “gate cloak” that will last for the duration of your session change timer. So every time you jump into a new system, you end up being cloaked on the other side for 30 seconds. During this cloaking effect, other parties on gate will not be able to see or target you. As you session change timer expires, your gate-cloak will drop and you will become targetable. While you are cloaked you may observe the situation around the gate and report it to your fleet commander. Once the cloak drops you have to decide what to do next: return to previous system, warp off, or go sit on the gate if it is clear.
The session change timer is also very important upon undocking. Just like with gates, undocking you are granted certain period of invulnerability. If you break that period of invulnerability too early, the people sitting around station camping you will be able to target you and kill you. However if you can keep this invulnerability entire 30 seconds you will be able to successfully redock.
When you undock you are granted a period of invulnerability of 30 seconds. This invulnerability last as long as your session change timer goes on and it gets broken if during these 30 seconds you: 1) Activate any modules on you ship, even just like hardeners or damage control. 2) Initiate warp anywhere. 3) Double click anywhere in space to move to that direction.
Broken invulnerability means that other ships camping the station will be able to lock and fire on you. Meanwhile you won't be able to dock back up to station because your session change timer for 30 seconds still did not expire. This will lead to destruction of your ship at undock point of station. To avoid this do not break your invulnerability prematurely. Enablethe session change timer on your screen, see when 30 seconds expire and the timer disappears, and only request to re-dock.
Step-by-step instructions:
Using the session change timer and 30 second of invulnerability that it grants you to your advantage, you can thus undock and gather intel for your gang on what ships are camping outside while still keeping alive yourself.
Big ships take a long time to lock smaller ships. This means that if you undock in a small ship and see big ships sitting outside without any smaller tacklers nearby, you can easily warp away from them. However, just to make certain that you can redock to the station in case things go wrong, always wait out your session timer before initiating warp. If you see some interceptors, assault frigates, or frigates outside your station it might get a bit tricky as those ships lock very fast. This is why it is a good idea to always wait out yout session change timer before warping off anywhere.
Always have at least one fitted pvp ship sitting at another location. This way if hostiles are camping the station where you base, you can warp away in a pod, board your pvp ship at the other station and join your gang rather than be trapped inside the station and useless to your gang.
Undock bookmarks will let you escape a station camp even if they have fast tacklers outside. Here is how undock bookmarks are created:
You may have noticed that after you undock, your ship gets ejected from station at maximum velocity at a certain vector pointing away from the station. A ship can enter warp when it reaches 75% of its maximum velocity and is aligned to 5 degrees of its destination. So when you are undocking you already satisfy the velocity requirement. The undock bookmark will allow you ship to satisfy the second requirement as well as you will simply be warping forward. What this means is that you will be able to instantly warp away from station even if piloting a heavy ship. This way you can get around station camps.
If you get camped and cannot create an undock bookmark, then ask somebody in corp to help you out with it or simply use an alt to get yourself out. It is a good idea to create these bookmarks from stations you plan on basing at or fighting at before the hostilities start.
If you plan on redocking, hit Ctrl+Space to decelerate and not be carried outside of docking perimeter, wait out your 30 second session change timer, then dock back up to station again. However if you plan on warping to an undock bookmark, do not hit Ctrl+Space. If you hit Ctrl+Space your ship will decelerate then spend extra time accelerating again to initiate warp to your undock bookmark. This can give plenty of time to whoever is sitting at undock to warp scramble you.
Stations all differ in amount of undocking perimeter they have. Undocking perimeter is that area of space where you read to be 0 meters from station on overview while moving. Once you pass about 300 meters from station you will not be able to dock immediately. Instead your ship will have to fly back to station before it can dock. However if it is being webified, scrambled, and bumped away by other ships it will not be able to get within docking perimeter to redock. This is why “eject” stations present problems redocking.
There are a few stations that will catapult you 1000-2000 meter away from docking perimeter right unpon undocking. These stations typically belong to various Minmatar factions and look like this:
My ship is a white square and it ended up being 1000+ meters away from this station right after black screen was down. The characteristic marks of an eject station is the long undocking tunnel visible on the picture.
So if you see a station that looks like this, it is not a very good station to base at. Every time you undock from this station, you will have to scramble back to the docking perimeter to dock back to it. It is good to base at a station with a large undocking perimeter so that you have no lethal surprises upon undocking.