To attempt a UFO Interception select the global intercept command or click on the base you want the ship to be launched from. The second option only lists the ships at that base, where the general list is good for launching dropships but may be a little too cluttered for launching interceptors once you have a number of them.
While selecting the interceptor's destination, world time is halted. You can continue to scroll the map by way of the controls or the more recommended centre-on-location command (RMB). This is a great way to pause the map in order to survey the globe if there are too many things happening at the same time - and if your Geoscape time is moving too fast for your liking.
- Elerium-based ships have the highest acceleration and maximum speed but the shortest air time. Conventional aircraft have the longest air time, but are very slow. By virtue of its speed and large fuel capacity, the Avenger has the longest range overall, about twice that of a Skyranger.
- Your ship autopilot prefers to move along lines of latitude (parallel to the equator) for long-range travel. This is especially noticeable when charting trans-polar routes: the ship will circle around the pole instead of flying straight across it. You can shorten the route taken by directing the ship to several intermediate waypoints along a straight line towards your destination. This way, you can probably squeeze a little more range out of the Lightning, which has very little air-time.
- Note that when you tell your craft to intercept a UFO, they will head directly for it. This is fine when you have plenty of fuel spare or it is headed directly towards you. If the UFO is travelling at an oblique angle to your base however you will find that your craft will follow a roughly parabolic arc in its pursuit, using up more fuel and time than is strictly necessary. It may be worth trying to judge an approximate interception point and sending your craft to that waypoint and then retargetting as the distance closes.
- Ship weapons will fire continuously at set intervals (based on weapon speed and range) at an enemy target as long as it's within minimum firing range (represented by the range bars) - until it runs out of ammo.
- Multiple ships (up to 4), can join the battle by way of minimising the controls while in stand-off and waiting for extra friendlies to arrive on the scene. This can be key if you only have interceptors when a battleship turns up.
- The different firing modes have two effects. Firstly it affects the distance of the interceptor and the UFO, and the closer you are, the faster the combat between UFO and interceptor becomes. Note, this controls the exchange of fire between individual interceptors and the UFO only. If you have two ships engaging the UFO at the same time with, the one on cautious will give and receive fire at a slower rate than a ship that's aggressive. The second effect is that it makes it harder to break off, and for the UFO to escape.
- When chasing a ship, if the UFO starts to back off and you minimise the window, you must wait until your interceptor starts to catch up with the UFO before you re-open the intercept window otherwise the interception will break off and will only start again once the UFO is back in stand-off range. If you let the UFO get away, the interception will halt and will only resume when the ship catches up with the UFO again - the net result is the same. The only difference is that the first method keeps the intercept window open while the other mode exits and then enters the intercept screen. There's no real advantage to this, except perhaps in TFTD when your ships are near the coast.
- When intercepting a UFO, you may want to take care where you actually complete the interception - sometimes you might have little choice, but if you shoot down a UFO over water you will not be able to perform a UFO Crash Recovery mission later. In addition shooting down a UFO (and later performing a mission on the crash site) over a sponsor countries airspace will cause increase in XCOM activity for that month (based on the score awarded), which helps keep that country happy and might persuade them to increase their funding at the end of the month.
- Also be aware when intercepting using cautious attack that there is a bug when you fire you final shots that will cause them to always miss.
- Multiple ships take a UFO down faster, and the UFO fires back at all of them that are in range in turn making each of your craft more likely to survive. Try to make it so that all your ships come into firing range at once so you can maximise the advantage of bringing them all together.
The Interception Window shows several things. It graphically displays the range, type, and remaining ammunition of the Interceptor's weapons with small brackets, shows shots traveling to each combatant, indicates distance to and relative size of the UFO, and shows the amount of damage that the interception craft has taken so far.
There are several commands available to you in Interception.
- Standoff (Top Left): Aircraft maintains standoff range with UFO. Neither side can shoot due to range.
- Cautious Attack (Top Right): Interceptor will close to the UFO until it can fire its weapon with the longest range(without paired weapons, only one weapon will be brought into fire.) Should this weapon's ammo be depleted, the Interceptor will then close until the other weapon can be brought to bear. Should the Interceptor be damaged by alien fire, it will retreat back to Standoff range and mode. UFO has a good chance of successfully fleeing if interceptor's top speed is lower.
- Standard Attack (Top-middle Left): Interceptor will close with UFO until it can fire both weapons and then maintain that distance. If Interceptor is damaged badly in a single shot, it will retreat back to Standoff range and mode. UFO has a chance of successfully fleeing if interceptor's top speed is lower.
- Aggressive Attack (Top-middle Right): Interceptor will attempt to get as close as possible to the UFO, firing both weapons as soon and as often as possible. Interception craft will not retreat regardless of damage, unless switched to a different combat mode. UFO will have difficulty fleeing combat even if interceptor is slower.
- Disengage (Bottom-middle Right): Interception craft will disengage UFO and start returning to base, though it can be ordered to do something else as soon as combat is broken.
- View UFO (Bottom Right): View a side picture of the UFO; the same picture that will appear in the UFOpaedia upon successfully gaining the details of the vessel from an alien Engineer. Can be used to identify targets.
Every time the weapon for an Interceptor hits, it will deal anywhere from 50% to 100% of the damage rating listed on Craft Armaments. If a UFO has taken 50% or more of its damage capacity in Interception damage, it will crash-land(assuming it is over land) and X-COM will be credited UFO Grounding points and can later launch a UFO Crash Site raid to clean up anything less. If the UFO takes 100% or more of its damage capacity without crash landing, the UFO will be destroyed. No crash site will be generated, and X-COM is credited with UFO Destroyed points(which are double the points given for Grounding the UFO. It should be noted that some UFOs yield enough points in recoverable loot to make it preferable to ground them instead of destroy them).
You can use this command to make ships act as mobile radars, sending them out to areas of suspected alien activity. Particularly when looking for Alien Bases you will need to patrol a suspect area, but your crafts localised but powerful onboard radars can be useful elsewhere, and means they can be sent after a UFO which has left your tracking radius and should be able to reacquire them if you can anticipate the UFOs movement in the interim. Another potential benefit is that Interceptors and Skyrangers will consume half as much fuel when patrolling than when flying around at top speed, which can make one or two around even in the later game when they are mostly redundant at their original roles.