Has it ever happened?

Has there been any indication from any police department or any airline that it might happen?

Have you ever heard of the term, "Theft of Services"?

When I was at American, we had a passenger board and "just sit in an empty first class seat". The lead flight attendant realized soon enough he wasn't supposed to be there, and asked him his name. He replied, she checked the manifest, and explained to him his seat was in the main cabin. His response was a simplistic "well, this was open, so I'm gonna sit here instead". Instead of making a huge scene, the flight attendant walked away, and offered the passenger the same amenities throughout the flight as she did to the other first class passengers.

When they landed at our station, the police met the aircraft, and it was explained to the gentleman he could either pay the difference between his 21-day advance purchase coach and full fare First (if I remember correctly it was around $1400), or he would be arrested for "Theft of Services". He paid.

Granted this is an extreme example, and most likely, the flight attendant would "loudly" explain that you need to take your seat in coach.

We put up with enough these days, and contrary to popular belief, do not enjoy confrontations. Please just follow the rules, everybody else has to.

Oh, and btw, this topic has been discussed a thousand times before.

Travis

Given the reports we have read, people sneaking up into first class happens on flights quite regularly. I have observed it myself on several occasions, as have many of us. And yet, a search of the internet doesn't show up a single case of an airline doing anything other than sending them back. No arrests, no retroactive billing, nothing.

So what are these threats of dire consequences based on, other than a sense of superiority on the part of legitimate premium-cabin passengers?

You are the one that is playing "internet lawyer" by describing consequences that don't exist in reality.

I am answering the question based on actual experiences of passengers.

If no one has ever been prosecuted for this "crime", despite hundreds of people doing it every year, then that is a pretty good indication that it's not as big a deal as you think.

I was working as Purser several years ago on a 777 from Denver to IAD. About 2/3 of the way through, a FA from business came up and told me that two passengers sitting in business were not on the manifest. Apparently the psgrs were exceedingly nice, and the FA wanted to know their names to thank them.
They were premier-level psgrs booked in row 17 in economy. I confronted them and they admitted that they decided to upgrade themselves since business was only about half full. At this point we were about 30 min from landing. I told them they could stay were they were, but a CSR would meet them upon landing to deduct miles from their account for the upgrade.
They were escorted out to the podium, and a few minutes later the CSR came down to ask me what happened. Apparently they told the CSR that they "accidently sat down in the wrong seats".
Long story short they were each required to pay $630 and a police officer was there at the podium and would not let them leave until the credit cards were handed over! They did not look like happy campers when I walked by!

As we had many hours until arrival, the Purser told the pilots, who had time to coordinate with IAD customer service, law enforcement, and the immigration folks (she seemed to be Italian). When we arrived at IAD, those people came on and surrounded her. She claimed not to have a credit card, but was given the choice of either arrest or not being admitted into the U.S., or coughing up a credit card. A credit card appeared. The look on her face was priceless.

14 ARRESTED AFTER ECONOMY PASSENGERS STORM FIRST CLASS
By Pat Hurst, PA.
Angry economy passengers stormed first class on an international flight in a
mid-air upgrading mutiny, it was disclosed today.
The pilot of the packed Pakistan International Airlines jet radioed ahead, and
14 people were arrested on suspicion of endangering the aircraft after landing
at Manchester Airport.
Cabin crew lost control after the flight was delayed for four hours in searing
heat on the tarmac at Islamabad airport in Pakistan.
With economy packed, a number of passengers decided to upgrade themselves to the empty luxury section at the front of the Boeing 747.
It is believed the crew asked them to move but they refused, so police were
called in as the plane landed in the UK on Friday morning.