Can small arms fire bring down a commercial jet?

Factual Questions
21

Thanks, Hail Ants, for the supporting opinion. I’ll also agree with Bosda’s assertion that a lot of small arms firing together might do it.

I note that initial speculationis focusing on the engines. The Airworthiness Directive in question is, again, addressing “uncontained engine failure” due to “cracks which can cause separation of the HPCR stage 3-9 spool”(can’t post a link, but if you go to the FAA’s web pageand search for “2000-NE-31-AD” you’ll find it). Basically, a crack from metal fatigue is suspected of being able to cause a failure some stages of the high-pressure compressor. For more information on the CF6, you can check out GE’s web site on the engine.

22

True, but not for the reason you state.

At the muzzle, a typical shotgun slug has between 2300 and 3300 foot-pounds force of energy, depending on load and other factors. Compare that to a typical .308Win load producing around 2800 ft-lbf at the muzzle, or a .30-06, ranging from about 2600 to 3200 ft-lbf at the muzzle. All are fairly comperable, at the muzzle (differing loads will produce differing energy levels, and I use these numbers for illustration only. Depending on load characteristics, YM Will V).

The real issue is that shotgun slugs lose about 50% of their energy after the first 75 or so yards, and so are short ranged ammo, at best.

As for small-arms vs. large aircraft, well, as some of y’all may recall, my father is a aeronautical and mechanical engineer (something of a ballistician and mathematician too :wink: ) who has been called out on aircraft crash investigations. One was a Navy P-3 that suffered a catastrophic fuelcell explosion in a wing in mid-flight. At the end of the investigation, it was determined that the aircraft had been hit by a single high-powered bullet, fired from the ground. This bullet, likely fired by a hunter ('twas deer season, and the fly-out path was right over prime hunting grounds), struck a fuelcell and punctured it, releasing fuel. It also ignighted a supposedly fire resistant rubber grommet. The burning grommet acted as a pilot light, and when the fuel tank had bled down sufficiently to create a stochiometric mixture of vapor and fuel, the cell exploded. The proverbial “Golden BB”. It is believed that the flight crew was unaware of the leaking fuel, although no one knows why they missed this information.

By the time the cell exploded, the aircraft was well away from the airfield, and no one intitially connected the hunting season and the crash. It wasn’t until midway through the investigation that my father noticed the characteristic tear that bullets cause in in aircraft skin (being a combat veteran comes in handy in the oddest places), and the team began to put things together. Subsequnt investigation identified the hunters in the area the day of the flight, and interviews turned up a hunter that admitted to “firing in the general direction of a airplane that scared off his deer”. It appears that his frustrated shot had precisely the correct lead and elevation, all unknowning. No charges were filed.

So: Given a string of highly improbable coincidences, a random shot can fell a large aircraft. At least once.