Can a handgun shot take down a commercial airliner?
shooting at it with a handgun


That's really going to depend on the handgun.

James Bond carries a Walther PPK - this is a .32 calibre popgun with rather limited use outside of a small office. Direct hits on people are usually survivable unless you take a round in the heart or brain. Chances of even hitting an airliner during takeoff or approach are zero - it simply doesn't have the range, and that tiny subsonic projectile will get deflected by the aircraft's wake.

Skipping the middle range and going straight for the hand-cannons, we might get somewhere with a Desert Eagle or a Smith &amp; Wesson 500. Remember the posters for the first Terminator movie? The one where The Ah-nuld is wearing sunglasses and holding up some light artillery? These are bigger. At close range, both guns can crack an aluminum engine block1 and are one-shot kills on most things smaller than a rhino. Hitting an approaching widebody isn't all that difficult - it's coming toward you, the angle isn't changing, and it's a rather big target. 

But aircraft are large, complex systems with a lot of redundancy, so in order to actually take it down we have to hit something critical. Hitting a 767 right in the nose will destroy the weather radar and (maybe, if it has enough energy left) poke a 1/2 inch hole in the forward bulkhead. No one will notice. The flight-deck windows are rather strong, apparently a police sniper tried to take out a hijacker on the flight deck way back in the 1970s and the rifle round (far more powerful) just pock-marked the window. Several hostages were promptly shot as a result.

The best shot (ha!) is the engines. They don't like ingesting bits of metal but just hitting the fan won't do much. You would have to get very lucky to get the round into the engine itself, where it will promptly do a lot of very expensive damage.

But even if one engine literally goes boom it still won't crash the plane. Pilots practice for an engine failure on takeoff all the time, and an engine failure on landing is almost a non-event.

Hydraulic lines for control surfaces are certainly sensitive, but they are well buried in the structure and there are several independent systems. You won't get them all.

So, in conclusion, handguns are sufficiently ineffective at bringing down large aircraft that we really don't need to be concerned about them. There's a reason air forces around the world prefer missiles or 20mm cannon2 for this sort of thing. Geese, however, are quite effective if released in sufficient numbers along the takeoff path. Rather noisy though - you won't hide 500 of them anywhere near an airport without someone noticing. 




Internet legends of a .50 cal being able to kill a truck refer to the MUCH larger .50 BMG round, available in explosive and armour-piercing and rightfully categorized as a first-class military weapon.
The projectile's the size of your thumb, and the gun fires 6,000 rounds per minute. It'll do your plane like a chainsaw.