I suppose anything is possible, but the most plausible theory I've heard is that the flight leader's instruments malfunctioned and they ran out of gas and crashed over the ocean.
The Bermuda Triangle is a just a superstition and not an entity that can cause crashes. There is surely a good explanation but we just don't have the evidence yet.
I believe in aliens. I think alien activity is the reason for the mishap of flight 19. I think that all ships and aircraft that crash in the Bermuda Triangle is due to an alien presence.