Yes; explosions have a spherical radius with diminishing levels of damage as you travel from the center. Any unit too close to an exploding ship/plane/piece of ordnance will take damage if it is within the danger zone.
Another interesting detail is that plane wreckage can damage ships (not just the main body of a plane!) I once saw a Ju-88 get shot down - the broken off wing plunged onto a cargo ship and set it on fire. Quite a surprise!
