I was just delayed for six hours at JFK. Technically, this was not a "tarmac delay", because we were at the gate with the door open rather than "on the tarmac". However, the captain told us that the plane was about to take off (although in fact it was delayed three more hours), and that if we left the plane, the doors would immediately close with no warning, and the plane would fly off without us. Of course, that would leave us stranded in the airport with no flight and no luggage, so everybody stayed on the plane, so it might as well have been on the tarmac. But would they really have just taken off without you with no warning, with your luggage still on the plane? Was the captain just bluffing?

You've got a lot of variables in that scenario - but the short answer is yes - planes take off every day with passengers standing outside the jetway (usually upset).

In your situation, I would interpret the message to be that the delay is indeterminate and that if the captain gets clearance to push back he will immediately do so and those who have stepped off the plane may not be able to get back on. Whether that clearance will come in 3 minutes or 3 hours remained to be seen. But the captain wanted folks to know that there were no promises and that those who chose to step off took their chances.

Though, of course, if you had a checked bag in the hold, that would need to be found and offloaded; this has been standard since Lockerbie. More than likely the Captain was doing his best to deter people from stepping off the plane for this reason.

Most certainly they will leave you if they need to get moving fast and you are not around. Which can mean the difference in getting airborne in 25min vs 3hrs.

Yesterday I had one going to KEWR that had a 2hr EDCT that got shortened to 20min which if missed would turn into a ground stop. They were boarded at the gate and just needed to close up and push back, which took 10min, then a 7min taxi and 2 min for the runway to clear, take off and tag up ment they barely made it.

I thought passengers aren't allowed to get out of the plane after you've boarded the plane?

Different rules for international versus domestic flights.

Happens often enough. I've been that person at least once. And US DoT rules require that you're given the option for such if there is a delay that will exceed 3 hours.

Not true.

I've had the "stay close to the gate, we could have at any time" version and once when seated in F the crew pretended to not notice when we took our PDBs with us.

OP was at JFK. If this was a US carrier, that silliness was stopped in 2003 for domestic departures and it would not likely occur in this situation for an international departures. This occurred when the US moved to 100% screening of checked luggage.

While this would have been an issue for BA or on departure from the UK, that is all due to antiquated rules and lack of technology.

It is fairly routine for rolling departure delays to occur. It would be interesting for OP to post the carrier and flight. Most often, the Captain will advise passengers that they may deplane but do so at their own risk. For a smallish aircraft, it may be possible to push in <5 minutes so if the Captain obtains clearance, it is easily possible to depart with passengers standing around. For larger aircraft, it would be normal to advise that passengers should not leave the gate area and that while every effort will be made to make announcements in the gate area, there are no guarantees.

AA has a "we are headed to XXX, if that's not your final destination now is the last chance to deplane" announcement on every flight.

No, and No.

Since at least 2011, but I believe it was much earlier than that.

14 CFR Parts 244, 250, 253, 259, and 399
Docket No. DOT-OST-2010-0140
RIN No. 2105-AD92
Enhancing Airline Passenger Protections
AGENCY: Office of the Secretary (OST), Department of Transportation (DOT).
ACTION: Final rule.

Yeah, I recall a flight some years ago. We weren't at the gate so there was no issue of getting off but we were on a weather hold, estimated 2 hours (this after already boarding way late.) Not a good thing for us as that guaranteed a misconnect.

An hour into the hold the pilot comes on, "We have a window if we take off now, flight attendants take your seats." The engines were spooling up as he said that. We got in 20 minutes before our next bird was scheduled to fly, we got there and nobody around except the GAs but the door was still open. Our seats had been given away but they found us new ones in business (three-class airplane, they were nice.)

I was on a delayed flight the other day that was then delayed an extra hour while they searched for and removed luggage of people who weren't on it. Nobody got onto the plane after it was announced that this was happening. So, someone got left behind. Or perhaps they had made their own way to Europe. (There was a FlyerTalk thread where someone was being advised to do this.)

PS: It appears that banging on windows and asking a pilot to 'Please come back' doesn't work: https://www.youtube.com/watch?v=Bk_G1Df0_qg

In theory its different for international but when I got delayed in Chicago in July beyond the point where I was going to be able to make my international flight in LA I had my flights changed to the next day my checked bag still flew to LAX on united then made the American flight to AKL that I was supposedly going to miss and arrived in Auckland 24hrs before me

Happened to me again yesterday. They held the plane while passenger's luggage was removed.

Happens the whole time, just not in the USA for domestic flights where the security is less tight. It seems guns rather than bombs is their preferred choice.

More likely that simply enough time had passed since the last bomb in hold mid-air explosion scenario that the airlines' lobbying to make life easier for them was successful.

If it ever happens again involving a U.S. plane or on a flight to/from the U.S. expect that to be changed again.