"No crew available" and "aircraft problems" are often airline code for "there are too few folk on this flight to make money." America West were notorious for it.
Flying stories:
1) When I came to the US in 1997 I was in what must have been the oldest 747 in the British Airways fleet. Everything behind the engines was filthy black like the thing ran on coal. It was only flying to DC but it lumbered down the runway with acceleration equivalent to a sloth on tranquilisers. The take off run was so long and the rate of climb so pathetic I would not have been surprised if we took some perimeter fence with us. Actually, go to Google Earth and look up "Membury Services" on the M4 West of London. We probably hit V2 about there. I nicknamed this crate "The Banana boat" because every time it hit turbulence the center mounted overhead bins sort of snaked to and fro. More than one passenger looked grumpy at me when I pointed it out to the kids running around at the back.

2) I had to fly in a small twin here in Nevada. On the way back to Vegas we had Mt Charleston to the West of us on a day with a strong wind from the West. Of yes, the mountain had created a big invisible swirl in the sky and we hit it, going straight down in no time flat with the dash going red from the pilot's side to mine.
3) On a 737 in a stack waiting to get into Vegas when there were storms about. Some joker in ATC thought it would be funny to put one side of the stack in big CuNim. I woke with a start to find my arms floating up off my lap in negative G.
4) In the back of a big and heavily laden transport taking off at night I noticed that although I thought we had left the ground, we seemed to be descending. After a couple of seconds we seemed to be climbing again so I figured the runway had a sizeable "up and over" we had crossed just before lift off. I had never flown from that location before so I had no real clue. Find out three years later that the kite "had a problem" shortly after take off and had enough rate of descent that folks in the ATC tower were reaching for phones.




Apparently the crew sorted it out and we flew on.
5) One from my buddy. He was going back to the UK and for some reason he took a red-eye from Vegas to O'Hare to catch the flight over the pond in the mid morning. Did I mention it was winter?

The 747 was almost empty when they closed the doors because so many connecting flights did not make it in. After deicing (he thinks) the plane taxis out and takes off in a snow storm. He said O'Hare must have good ground markers because when he looked out of the window he could not see any clear ground or asphalt anywhere. Apparently the plane came off the runway like a scaled cat because of the lack of passengers (13 in economy, he reckoned) and was likely the last flight out that day.
6) Somebody with a sense of humour routed me from Las Vegas to London via LAX. An hour into the flight out of LAX (another British Airways banana boat) an attendant asked my why I was looking so annoyed stood looking out of the window of a rear door. I pointed to a spot in the city below and said, "I've been traveling for six hours, and I can still see my bloody house".



