[FreedomPoster]

And a missile going for "center of mass" of the heat sources, or dithering between two of them, might hit the fuselage.

[Non-Sequitur]

And a missile going for "center of mass" of the heat sources, or dithering between two of them, might hit the fuselage.

But IR seekers don't do that, they go for the heat source itself. And if it did 'dither' between engines then it would hit the wing, not broadside the fuselage.