There was a Belgian passenger plan that got lost on its way to Teheran and had to land in Grozny. Before GPS planes had literal human navigators with maps and sextants!
I would be more inclined to believe in the Bermuda triangle myth if it happened with modern planes and their transponders.
This story was why, since I was very young, I'd been fascinated by this scene:
There are better explanations than the vanilla call card of "conspiracy theory". One of them is that it is easy to get disorientated around there due a combination of many similar small islands in some areas and remote open ocean in another section, so it would be difficult to navigate by sight.
There are also widespread reports of magnetic anomalies which would mess with compasses, and it is within the hurricane zone providing another possible cause.
I sailed from Norfolk, Virginia, to St. Thomas, Virgin Islands. When we were in the Bermuda triangle, our ship's compass starting veering to one side, then made complete 360 degree turns, then started spinning. We were passing a magnetic anomaly marked on the chart. Fortunately, over time, the compass corrected itself. If we had been in an aircraft with limited time and fuel, I don't know if the compass correction would have occurred in time for the aircraft to resume course and land.