True. Avalanche Missiles will take down anything less good than a Terror Ship, though, like Supply Ships for example.
Supply Ships do have loads of armour, though, so you might want a couple of ships.
Did you know that Careful actually makes your weapons more accurate too. It's pretty handy when you really want to take down small ships, for whatever reason.
In other news I R TEH 1337th POSTZORX!!!12!!
*edit* : seems Another Guest is the 1337 poster. Oh well.
*extra edit* : Another_Guest, why are you using anything larger than a Skyranger on Alien base attacks? They can carry enough soldiers and equipment to get the job done, especially if it contains 14 people with Laser Rifles and Alien Grenades.
Another_Tip for you (see what I did there? Hehey) in cities or alien bases, if you see any red barrels and/or a petrol station, if you fire on it, it will blow itself up. Here is a tip I learned by accident, though. If you Auto Fire on them, then the barrels / petrol station will not be destroyed until all 3 shots have gone, however it will explode 3 times.