Maybe the terrorists aren't as fixated on planes as the westerners are after 9/11? I've noticed that when you add "...on a plane" or "...at an airport" to things that people otherwise wouldn't care about, suddenly it's a huge issue. While there are certainly special considerations that need to be made for safety in the context of air travel, there's many easier ways for terrorists to make a statement and kill a bunch of people. Fill a U-Haul with a couple tons of explosive. Fill smaller containers with explosive and distribute them around a city. Walk into a crowd and open fire. Let out poisonous gas in a subway or other enclosed space. Car bombs in particular happen on an almost monthly basis in the middle east, and there have been quite a few high-profile terrorist attacks in the west since 9/11, none of them have involved planes. Boston bombing, Madrid bombing, London bombing, Charlie Hebdo, Ft. Hood. Terrorists aren't looking at planes.