It happened to me last year while "attempting" to fly
ADD to
NBO. There are many factors that contributed to it including my lack of sleep over three days of continuous flying and the chaos that is
ADD. I am in my twenties and an experienced flyer so no excuses there.
I arrived in
ADD on a Tuesday morning coming off a delayed flight from
BOM-
ADD and was mostly awake overnight in
BOM. This was the last leg of my three day journey which started the previous Saturday before
BOS-
ORD-
IAH-
DME-
SIN-
BOM-
ADD. Now if anyone has ever been to
ADD, the ground level gates where passengers are bussed to aircraft is simply chaos. Multiple flights leave through the same door, no indication on the FIDS when a flight is actually boarding, and they look at your boarding pass but don't scan (not that it would help but they should look at your boarding pass before letting you board the bus). I know I'm flying a 737-800 which I board. The purser looks at my boarding pass and waves me in. I find my seat and see someone sitting in it. We have the exact same seat number. The
FA said just take another seat as the flight was empty and I thought no more of it as I had asked the agent in
BOM to change my seat and figured the change hadn't gone through or something (really should have been my first clue). Having not slept except for the 3 hours on the previous flight I fall asleep almost immediately. I wake up when were descending and overhear the captain announcing we will be landing shortly in some city. I didn't sound like she said Nairobi. I was a little worried but there was no way I was on the wrong plane. It seemed so ridiculous. Then I thought about the seats. A reasonable explanation for two passengers having the exact same seat was that someone was on the wrong flight. I jump out of my seat and ask a crew member "where did the captain say we were landing?" to which she replied "Librevillle." I had gotten on the wrong bus. Now I honestly was not really panicked about this, just surprised. She seemed more horrified when I told her I was supposed to go to Nairobi. She took my
BP and spoke to the purser and came back and told me since the aircraft was turning around in LBV I could just come back with them. Upon landing in LBV the station manager already had new
BP for LBV-
ADD-
NBO. They handled it very well. The plane departed back an hour later, and I once again faced the chaos that is
ADD. This time there was a flight to
PVG and
CAI departing out the same door (imagine getting that one mixed up). But once again it was not made clear by the ground staff or the FIDS when the
NBO flight was boarding as there was also another flight out of the same gate that multiple went up to confirm which flight was in fact being boarded at a particular time. This time I was far more careful but just as confused throughout. I did confirm with the people on the bus that they too were going to
NBO and listened for the onboard announcement. I arrived in
NBO 12 hours later than planned but I wasn't upset per se, just tired. I mean I got to fly two more flights than I had planned, logged a new airport and route, and visited West Africa for the first time. My biggest regret is that I didn't get miles for it

My family were far more strung out about the whole thing and they could not believe that this could happen to me of all people as like many of us here, I am an aviation nut.