More generally, in order to be successful a traditional armor piercing projectile needs two traits in particular: it needs to be harder than the target, and the projectile needs to be robust enough to not disintegrate on impact. Airplanes are neither of these; they're built out of soft aluminum and are built light to maximize payload, not to be robust. Consequently I would not expect an airplane striking a reinforced concrete building to ever behave as an armor penetrating projectile would.
The part that I'm a bit skeptical of is the suggestion that shrugging off a Phantom is equivalent to shrugging off a 747, which is more than an order of magnitude heavier. Throwing an airplane at a concrete building is like throwing a wet ball of modeling clay at a glass window. Likely to splat, like that phantom did, but if your ball of clay is big enough it might go through. A large enough plane might even knock the building off its foundation, rather than penetrate the concrete.