I like your example about skydiving, but your reasoning is flawed. Hijacking a skydiving plane and crashing it into a building isn't likely to cause a lot of damage. More importantly, it's not likely to cause a lot of terror. The planes are relatively small, passengers are well equipped to simply jump out (therefore, no hostages), or some would happily make a fight of it, knowing they'd probably be safe getting out of the plane anyway.
Nevertheless, your point is important. There are a lot of potential "terrorist tools" that are not protected. How about a terrorist taking over a subway/train and running full speed until it crashes or derails? I can't be the only one who's noticed operators are almost always alone. Even during a shift/operator change, overpowering 2 of them wouldn't be difficult. Same goes for most other type of public transportation (commuter trains, busses, trolley, ferry, etc.)
There are a LOT of terrorist plot/targets that scare me more than a commercial airliner today. Lots of things that keep me awake at night and wonder about the world our kids will inherit. I'll be completely shocked if a commercial airliner type of plot happens again in my lifetime. At least in that environment people would be far more aggressive towards an attack during a flight. The US government is well behind the curve with TSA and it seems clear they are simply attempting to justify the TSA's existence.
Even less than fully fueled that thing could put a pretty big hole in a building and the cockpit doesn't even HAVE a door separating it from the main cabin. Yes, it might prove tricky to take over a flight full of instructors and students in the air, but given that legitimate customers have easy access to the airfield at ground level before and after a jump and there's no real security there it's not hard to imagine ways a sufficiently motivated and unscrupulous person could take over such a plane at relatively minimal risk to themselves and weaponize it.
But yeah, that's just one of a zillion possible threats anybody with half a brain can come up with. The current airport security model assumes the existence of terrorists who have a really weird set of characteristics such that they are simultaneously:
(1) sufficiently driven and resourceful to successfully bring down a plane via a bomb or weapons if there were no security (this is pretty hard)
(2) NOT sufficiently driven and resourceful to find a way AROUND the current security measures (even though this is easy)
(3) also NOT sufficiently driven and resourceful as to find some OTHER way of causing a similar amount of terror and damage, such as blowing up 5 busses or funding a half-dozen "DC snipers" around the country or blowing up the security line itself.
Nevertheless, your point is important. There are a lot of potential "terrorist tools" that are not protected. How about a terrorist taking over a subway/train and running full speed until it crashes or derails? I can't be the only one who's noticed operators are almost always alone. Even during a shift/operator change, overpowering 2 of them wouldn't be difficult. Same goes for most other type of public transportation (commuter trains, busses, trolley, ferry, etc.)
There are a LOT of terrorist plot/targets that scare me more than a commercial airliner today. Lots of things that keep me awake at night and wonder about the world our kids will inherit. I'll be completely shocked if a commercial airliner type of plot happens again in my lifetime. At least in that environment people would be far more aggressive towards an attack during a flight. The US government is well behind the curve with TSA and it seems clear they are simply attempting to justify the TSA's existence.