Planes never crash because of just one reason. Almost always, an accident is caused by a number of different things. Even though flying is very safe, planes crash because of several things happening at the same time. Many layers of defence have to give way to trigger a crash.
In 1990, James Reason, Professor Emeritus of Psychology at the University of Manchester, England, shared the Swiss Cheese model of how accidents happen. Picture many distinct Swiss cheese slices cut from various blockslined up next to one another. It’s likely that you won't be able to see through one of the holes as they are all located differently. Each piece of cheese stands in for a distinct element, such as exhaustion, bad weather, or inadequate training. Accidents happen when all the holes line up simultaneously, and the probability of such an occurrence is rare.
But, according to various surveys, the chances of such an occurrence are high during the following phases: It is the highest when the aircraft is about to land, followed by when it is taking off. The most common type of mistake done would be carelessness, like forgetting to check the hydraulic pressure for the landing gear and flaps during a pre-landing checklist or caused by bad decisions, like coming in too high to the airport. Forces acting on the plane were miscalculated 21.2 per cent of the time, and crew members didn't work well together 11.4 per cent of the time. 7.2 per cent of the time, the wind or runway conditions were not handled well. Yet, the possibility of a crash is one per 2.52 million flights. If panic does strike you during a flight, cling to your seat hard.