Unless you hit a critical component, it is very unlikely it would cause the airliner to crash.
You could be on the plane, and fire bullets all around you, and not cause the plane to crash.
Hitting an airliner with a .50 from the ground and causing it to crash, would deserve the TERRORIST OF THE YEAR AWARD.
Ducks have caused more crashes than .50 armor piercing bullets.
Mythbusters did some experimentation in a pressurized arirliner cabin. They shot holes in the fuselage, they shot holes in the windows and even blew windows out without any structural damage to the plane. It wasn't until they used actual explosives that they did real damage.
A few years ago we had an airplane hit a flock of geese. One of them hit just below the Captain's window, dislodging the windshield wiper. The windshield wiper flew into the propeller, which sent it lenghwise through the fuselage and into the thigh of the passenger seated in seat 2D. The NTSB narrative follows:
On November 8, 2000, at 1800 central standard time, a SAAB-340-B, N402XJ, operated by Mesaba Aviation, Inc., was substantially damaged when the airplane impacted a flock of geese during an approach for landing. The windshield wiper was torn from the airplane. The left composite propeller exhibited impact marks and chordwise scratching on the face of a propeller blade. Metal fragments punctured the left side of the fuselage and one of the fragments hit a passenger in the leg. The airplane landed without incident. The passenger was taken to a local hospital for medical treatment for minor injuries. The pilot, copilot, flight attendant, and the remaining 21 passengers were not injured. The 14 CFR Part 121 Mesaba flight 2831 had departed Minneapolis-St. Paul International Airport (MSP), Minneapolis, Minnesota, and landed at the Aberdeen Regional Airport (ABR), Aberdeen, South Dakota. Visual meteorological conditions prevailed and an instrument flight plan was filed.
The Captain reported the airplane was on the ABR ILS Rwy 31 approach at 600 feet above ground level when the airplane impacted a flock of snow geese. The Captain reported he decided to continue the approach for landing. Once on the ground the flight attendant informed the Captain there was a hole in the side of the airplane and that a passenger was injured. The Captain reported a doctor on board the airplane removed a piece of metal from the passenger's leg and administered first aid prior to the ambulance arriving.
The Captain reported, "When we looked at aircraft 402 it was pretty messed up. There were geese in both intakes, three holes in the side, prop blades with pieces missing out of them, a side window busted, both front windows hit and one wiper gone, the other broke off to the side, one gear was hit and one flap."
Anyway apparently the passenger's only request was that he be allowed to keep the windshield wiper as a souvenir.
>>Unless you hit a critical component, it is very unlikely >>it would cause the airliner to crash.
>>You could be on the plane, and fire bullets all around >>you, and not cause the plane to crash.
!!!WRONG!!! DEPENDS ON THE ALTITUDE OF THE AIRCRAFT.
Physics 101: the higher the altitude, the lower the
atmospheric pressure. That is why aircraft cabins are
PRESSURIZED. A typical 737 flies at 30,000+ ft, you need
oxygen masks at 15,000 ft. If the fuselage is punctured
while pressurized at altitude, everybody inside the cabin
will be killed either by lack of oxygen, or most likely,
by being extruded through the decompression hole.
Same reason shaving cream shoots out of a can, it's
pressurized....
Well, excluding the damage our fighter pilots did in WWII, that is. ;^)