I haven't had any horrible experiences stuck on an aircraft (worst was a couple hours waiting to deplane on arrival in KEF due to high winds), but I did have a dog of a time on recent trip due to cascading delays.

Original flight was supposed to be LAX-AMS-BLQ on KLM. LAX-AMS got cancelled T-24 due to mechanical on the incoming plane (not a huge deal) and I was rebooked to LAX-SLC-CDG-BLQ with an earlier LAX departure. Made it to SLC, boarded a 2-week old DL A330neo, pushed back, then immediately towed back in reporting engine issues. We sat on the plane for about 90 minutes until they finally decided to deplane, and then had a couple more hours of rolling delays at the gate until the flight was finally cancelled to the next day. One moment of comedy where one of the mechanics working on the engine visibly threw up his hands in frustration. They strung along the cancellation long enough that it was impossible to make any other TATL that day, even connecting via the east coast. A night in a SLC motel later, finally departed via a replacement A330ceo after another 75 minutes of tech delays. That delay caused me to miss my connecting flight in CDG, resulting in yet another rebooking CDG-FRA-BLQ with last leg on Lufthansa.

I finally arrived in Italy sans-luggage ~30 hours after I was scheduled to get there - bag of course got lost on the inter-alliance transfer in FRA and would take another 3 days to make it to my hotel. Total transit time was 48hrs across 5 different aircraft when it was supposed to be an easy 14hr 1-stop. In hindsight I absolutely should have fought to keep the transatlantic flight ex-LAX rather than accepting the original rerouting, or worst case pushed for a domestic connection via a bigger SkyTeam intl hub like JFK or ATL.

I was once stuck in Heathrow because of weather, eventually missing a connection in Amsterdam. I believe that the delay was about six hours, from a faulty memory. I think it was just that flights were taking off with additional gap between them, and this built up over time. Because of the missed connection, I spent a day in Amsterdam and headed off (to Japan) on the same flight next day.

I got stuck in (error fixed) Jeddah overnight, as a plane was faulty and they had no replacement. From memory, the flight was meant to depart in the afternoon or early evening, but it departed maybe 9am the next day. They didn't seem very well set up for the problem. There was a huge queue to assign people hotel rooms. When they asked if anyone would like to overnight in the lounge there, I went for that. Only about three of us did. I claimed one of the tiny rooms with a lay down couch and could sleep. There was free food and drink and generally it was comfortable. I heard from other passengers that the queue for hotel rooms lasted for hours and they assigned more people to rooms than there were beds in the room, expecting people to share beds with strangers. Even worse, anyone who had entered Saudi Arabia on a visa (as I had) was taken to a hotel downtown, and then they didn't turn up to collect them on time, causing ... stress. Also, when I had a look at the lounge film theatre the next morning, there were a lot of people in there asleep. I guess they were from my plane. I definitely think that for once I made the best choice to be an early adopter of the lounge solution.

If the airline itself arranged the hotel pick up, why would those people be stressed about timelines?

Because the passengers believed that they might miss the replacement plane. It doesn't take long in (error fixed) Jeddah airport before concerns about ... things not being done properly ... start to set in. Fortunately for me, because even though a Saudia employee told me that my flight would leave in the afternoon, I had lost faith and went and checked. Admittedly, she did come and find me later to correct that, but I'd already found out by then.

Because of Brexit, no compensation for late flight or compensation for additional costs once in the UK. So, even if the airline would have helped them if they had missed the morning flight, there quite easily could have been additional consequences for passengers stuck in Saudi Arabia for an extra day.

Late morning flight to MCO, all day delay due to thunderstorms.

We sat on the plane at the gate for hours and hours, watching the sky turn angry and purple. They finally took us off, as there were tornado watches everywhere.

We landed six hours late and didn't arrive to our resort till 9:30pm. Missing a day at the park, and an anniversary dinner reservation at a fine dining restaurant.

The resort was a 5 star resort and they upgraded us, as we were frazzled and so disappointed at arriving so late...to a $2100 a night room on club level which included all food.. So yeah, no complaints from us!

4 days , due to the Manchester power outage last Sunday our flight from Gibraltar to Manchester was cancelled, the funny part was Easyjet checked everyone into the flight knowing that it was cancelled and then left the mess for the Gibraltar ground staff to clean up!! Then easy jet said the next available flight was four days later on Thursday, we ended up going from Malaga which is two hours drive away on the Tuesday as did not want to wait so long!!!!

When BA introduced the 747-400 in to its LHR-SIN-Syd/Mel routes, they had a lot of teething problems. I used this route quite a lot, and had
1. 24 hour delay at LHR
2. Flight diverted to Athens. Some technical fault.
3. Transferred to an SQ flight from Sin to MCR
4. Flight diverted to AMS. (Crew ran out of time)

Of these, the time in Athens was the best. BA had 4 very senior guys from their then biggest customer on board, 3 in F. The Station Manager at Athens gave us some Greek money, and 2 of us took a taxi to a Bar by the sea near Athens somewhere. We drank rather a lot of Metaxa. And a modest amount of coffee.

In late May 1997 my father, myself and my friend were booked on the Thursday Cathay Pacific 747 flight from Perth to Hong Kong (PER-HKG). I remember this one clearly because of the series of events that cascaded in to the longest delay I've ever experienced.

After take off around midday, an engine issue occured, and after dumping fuel over the ocean we landed back at PER with emergency vehicles on the ground. Disembarked back to the lounge (my father had Qantas status allowing lounge access). Mid afternoon back on board, sat on the aircraft for a while, eventually offloaded and told the aircraft would not be departing that day.

My father went home, but my friend and I weren't going to pass up the opportunity of a free overnight hotel with meals, so off the Hyatt Perth we went.

Back to the airport the next morning (now Friday). Boarded late morning, taxied and commenced take off roll, but aborted soon after and returned to gate. Back to the lounge for many hours.

Eventually senior ground staff explained there was an issue with one of the engines and they were unable to get the part sent over - and Qantas didn't have one at their maintenance base in SYD. So we were stuck.

Now this is where it gets interesting, and explains why this delay kept snowballing. That same week in late May 1997, Cathay Pacific grounded it's entire fleet of A330-300s, due to an engine issue with the Trent 700's. Meaning that they had a large and sudden shortage of aircraft on their routes, and they weren't able to send a replacement aircraft (any aircraft type) down to collect all of us.

CX's PER-HKG schedule wasn't daily, and the next scheduled flight was on the Saturday (48 hours after our original flight first departed) but was fully booked, and we were told that they wouldn't be bumping anyone from there flight to accommodate us as it would mean affecting a second load of passengers (makes sense).

We spent the day in the lounge again, and around late afternoon we were shuttled back to the Hyatt. A reporter from the local newspaper came to the hotel, my friend and I were interviewed and our quotes were in the next morning's West Australian Saturday edition.

Now by Friday evening the novelty of free hotels, meals and drinks allowances were starting to wain. I had started a new job in the Philippines and was heading back to work after my first break at home in Perth. The Hong Kong trip was something for my father and I to do as it was one month before the handover and he wanted to see it again (my reasons were more avgeek related - to spend time plane watching at Kai Tak). I only had the weekend in Hong Kong before heading back to Manila on the Monday, and time was running out.

Cathay Pacific's Perth station manager agreed to meet us at the hotel, and after some protests from us, came up with a solution. They would put myself, my Dad and my friend on the late night red eye Qantas service from Perth to Tokyo Narita arriving the next morning (Saturday). My dad and I would transit on to a CX flight from NRT-HKG, while my friend would fly from Tokyo to London (his intended destination, Hong Kong had only been a transit for him.

We were upgraded to business class on the QF PER-NRT flight. My friend had some hilarious photos of the 3 of us clowning around which I'd love to dig out again.

Transit in Tokyo, Dad and I finally got on to Cathay metal for the flight to Hong Kong and arrived later afternoon on the Saturday, some 40? hours AFTER our original ETA on the Thursday.

Aftermath: both my father and I wrote to Cathay Pacific (old school - pen and paper through the post in those days!). Cathay Pacific duly came back with a compensation of AUD$1,100 each by way of a travel credit. I transferred mine to him, he and his wife eventually put it towards flights to Canada for a conference.

That's my longest ever flight delay. Above information is correct to the best of my memory - I'm sure the newspaper article survives in an article somewhere still.

1 week in Dublin in 2010 - caused by the Iceland Volcano eruption that shutdown air travel for 6 days. Worse places to get stuck, especially as was there for work :-)

About 24 hours, give or take. A few years back was flying CO (not yet UA) GRU-EWR. Plane loses electricals over the Amazon, more or less glided into Manaus, which was not designed to handle a widebody (at the time). Had to disembark via stairs and into tarmac. Plane cannot be repaired, off to a local hotel. CO flew a small jet from GRU with parts and a repair team next day, plane fixed. Off to EWR 24 hours delayed. Fun time, got to do some sightseeing in Manaus, see the Amazon and the spider monkeys. Manaus is definitely something out of a magical realism novel, really no reason for the place to exist.

On the last day of the 2000 Winter Olympics, I'm flying home from Anchorage, connecting in Salt Lake City (the host city for the Olympics). My Anchorage flight left at 0630, arriving in SLC around 1000, I knew. flight operations for the entire airport were going to be closed during the closing ceremonies, so I knew I would be spending the day and most of the evening in the airport. Bonus: I got to talk to Adam West in the Delta Sky Club or Crown Club, whatever it was then. 2200 rolls around, and we're lining up at the gate for our outbound flight, in my case to Atlanta. Gate agent comes out to tell us that airport security got around to noticing that the metal detectors were unplugged and no one knew how long they had been that way.

The decision was made to "flush" the terminal, with everyone required to go outside and come in again through the security checkpoint. This was especially distressing for me, as not only had I already been in the airport for a long time, but I had gone through security in Anchorage and never left the sterile area in SLC. I and 5,000 or so of my closest friends exited the terminal and went through the metal detectors to get back into the terminal.

By the time I got back to my gate, my flight had departed. The Delta gate agent told me there would be no flight for me until about noon the next day, and there were no hotel rooms to be had because of the Olympics. So, I spent a cold, sleepless night wandering around the SLC terminal. I spent about 26 hours at SLC, and total transit time, ANC-ATL was around 36 hours.

On ground delay
 

I sat on a plane from 7:30PM to approximately 4AM next day. Flight was Shanghai to Hong Kong.

Ultimately arrived at lunchtime.

I had a delay of around 30 hours. AKL-IAH-MIA around 2019 for work. We arrived at AKL , went to check in and were told that the jet normally used had been sent to one of the Pacific Islands to help with a jet shortage. It was supposed to be back in time but then we were told there would be a 5 hour wait, so we went home. We came back later and checked in, then waited and waited. About 7 hours later we finally got to board. Luckily we were J, and were met with a pre flight drink.Unfortunately, while we were waiting for the flight a storm had come in and closed the airport due to cross winds. This isnt usually a long issue, so I had another pre flight bubbly and started to watch a movie. An hour later and the wind was still ferocious. This was around midnight, so I asked the crew if we could have our meal on the ground and then after takeoff we could sleep uninterrupted by service. They thought this was a good idea and started our meals. One unusual aspect was wine. We were allowed champagne as pre departure drinks, but the alcohol licence prevented them from serving anything else. We finished the meal, I was way past the movie, then started thinking when the crew would time out. And about 2.am they called the flight. Everyone had to get off and wait for an announcement at the gate. There was more bad news. Due to the wind, no staff were allowed outside to get the luggage. About 10 pax had carry on, so we were allowed to leave, clear immigration ( yes, we left the NZ border, no we did not travel) and go home. It got even weirder as the storm had taken out the power and there were no lights.
The next day, I checked the re-scheduled flight, got to AKL and found another 3 hour delay. But the flight finally left. Unfortunately, we missed the IAH connection and had to wait there for another few hours.
It was more an interesting experience than some of the traumatic flight experiences we hear about