AirplaneWhen airplanes crash, electrical or engine failure due to some mechanical problems is often the first thing that comes to mind. But in many cases, these accidents are caused by pilot errors — which even the pilots themselves are not aware they committed.

Here are three horrifying airplane crashes caused by human error:

  1. TransAsia Flight 235

On February 6, 2015, one of the engines of the TransAsia Flight 235 experienced a flameout. Though it seemed like a major problem, it’s one of those hitches that pilots could solve since airplanes can fly on one engine. However, the pilot on this flight accidentally shut off the functioning engine instead of the problematic one. He tried to restart both engines but failed. The plane plummeted into a Taiwanese river, killing 37 of the 53 passengers on board.

  1. United Airlines Flight 173

Running out of fuel is, unfortunately, one of the most common pilot errors, according to MyFlightSolutions.com. You would think it was impossible, as current passenger aircraft already have the technology to easily detect the level of fuel. In the case of United Airlines’ Flight 173 in 1978, the pilot and flight crew got distracted by a faulty landing gear. While assessing the problem and preparing for an emergency landing, they didn’t realize that their aircraft was about to run out of fuel. The plane crashed in a suburban neighborhood in Portland, leaving 10 of the 189 on board dead.

  1. Adam Air Flight 574

This is a similar case to the one above. The main culprit? Distraction. The crew of Adam Air Flight 574 became too focused on the malfunction of its inertial reference system that they didn’t notice the plane descending at a dangerously off-center angle. Flight 574 crashed into Indonesian waters, killing all 102 people on board.

Pilots are the kings of their aircraft. Passengers expect them to be efficient and to maintain control of their plane at all times. But pilots are humans, too, and may commit big errors that would cost the lives of hundreds or thousands of passengers. The abovementioned cases have become textbook examples for future pilots, to warn them to remain focused and maintain situational awareness in the cockpit.