War and peace aren't that simple. Russia already shot a passenger plane down and nothing happened.

They already shot down a civilian plane in 2014, killing hundreds of people, including many citizens of NATO countries

Possibly, but also keep in mind article five doesn't say that any hostile act leads to automatic full scale war in response:

The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognized by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.

Emphasis on "such action as it deems necessary," meaning a country can individually respond with its own discretion on what it thinks is a proportional response. Though in practice any response and individual contributions would be heavily negotiated within NATO. Theoretically a country could say it deems no action necessary even if article five was invoked. Just another reason why electing pro Russian leaders like Trump, Orban, or now Fico in Slovakia are dangerous and threaten the existence of NATO, even if they don't technically leave NATO.

https://www.nato.int/cps/en/natohq/topics_110496.htm

MH17 was shot down by a Russian Buk system given to the separatists, and likely with polite green ‘advisors’ nearby to set up and operate the SAM. Once they realized their fuckup they rushed it across the Donbas and back to Russia, but it was spotted several times en route both ways.

If that didn’t count, why would much harder to prove jamming trigger A5? NATO forces (yes, even Poland) are not risking escalation on their territory, even if that means Russian helicopters and cruise missiles can ‘temporarily get lost’ in NATO airspace.

So, first off. There is no reason for GPS jamming to cause a crash. Modern airliners have other ways to navigate.

Now it is possible to target a single aircraft with GPS "spoofing" potentially, but both GPS and Galileo have ways round this (Navigation Message Authentication). I would like to think aircraft navigation systems should be using this system. But, even if not, I'd bet it's still quite hard to reliably spoof a specific location to a moving aircraft.

What are you expecting NATO to do? Going to War^tm^ over one measly airliner and a few 10's of random people isn't an option here and all the parties understand that. Are you willing to see and be a part of the millions of deaths that the War^tm^ would bring? Because you know SOMEONE would push the Button^tm^ and Armageddon would happen.

Obligatory Tom Lehrer: [(https://www.youtube.com/watch?v=yrbv40ENU_o)]

if one of these crashes, wouldn’t that be considered an act of war and trigger Article 5?

Article 5 is, ultimately, triggered by action within the EU. If Europeans want to treat this as another Boeing nosedive rather than a military action, they'll wave it away.

As it stands, Vlad has been growing support within Southern European parliaments - Italy, Greece, France, Spain - and that might make invoking Article 5 more difficult than pointing at a downed airliner and proclaiming "Russia did this".