What has been the absolute scariest airplane flight you’ve ever experienced? ~

For the flight itself we took off from Pittsburgh but stopped climbing at about 1000 ft. Slowly we turned around, heading back, when the pilot said on the PA "Sorry folks, we are having a problem with our hydraulics system and need to return.". After we landed and got to the end of the runway, he said we had just enough hydraulics to get there, but not enough to get to the gate. It wasn't that scary to me, but I saw others white-knuckling.

A flight over the Atlantic, halfway through, they said they ran out of booze. 

Flight was from Gatwick in London to Atlanta, GA.  I had prearranged a shuttle to get home from Atlanta.  The flight was fine, almost pleasant.  My seat buddy was a commercial pilot from Norway.  I hate to fly which he picked up on right away.  We talked about all kinds of situations pilots face.  I asked him why the engines revved (seemingly) right before landing.  He explained the need to have the power necessary in case something happened which made is necessary to abort the landing and ascend.  Well, when we were landing.....I mean we were almost on the ground, the plane shot (what felt like) straight up.  Many people on the plane screamed, including me.  I also grabbed the pilot's leg as well as the guy's on the other side of me.  He was reassuring that the pilot had to make a split-second decision because of one of several things.  He also said it uses a whole lot of fuel when they have to do that.  After circling the airport a couple of times we safely landed.  After I got off the plane I started crying I was so glad to be off the plane.  Amazingly my flight landed five minutes early.  I went and got my luggage and then went to the designated pick up door for the shuttle.  They weren't there.  I called the office and I was told they left me 30 minutes prior because another rider on the shuttle was a doctor and insisted they leave because he had an emergency.  I went to war with those people and got a whole more than the $100 shuttle fare back.  The airport people were so nice tried to put me on a flight to get the rest of the way home.  No way in hell.  I rented a car and drove home.

A flight from Trenton RCAF base to Winnipeg in an ancient twin engine prop aircraft. An engine conked out and the pilot announced that we had about a half hour flying time to find a safe place to land before the other engine blew up. An SAC US air base in Michigan responded to our MAYDAY and it seemed, reluctantly gave us permission to land there. The landing was a bit shaky (we were slightly overloaded) but very nicely down to earth. Our ancient old beat-up Dakota aircraft looked kind of raggy against those state-of-the-art SAC bombers.

I've been on many flights with severe turbulence, but I'm not easily scared.  I've been on turbulent flights where most of the passengers were scared.