Actually the Army has developed just such a weapon. The EMP devices I am referring to needs a fairly large truck to transport. The reason the terrorist have not used these weapons is probably the reason you discussed earlier. Not enough bodies, blood and graphic gore. But I dont think you can count on that to remain their on going strategy.
Much of the airports and airplanes are shielded,
At the very least an airport is going to loose its radios and radars which by necessity of operations can not be shielded. They could be hardened but at this point I dont believe they are.
Terrorists’ love of blood isn’t part of their strategy, it’s part of their identity.
The airports can shutdown. And the planes that are in pattern can figure it out themselves. I’ve been to untowered airfields, a fairly busy one even, everybody talks to each other. It’s a little scary at first but it can be done.