The November 4th at 5.13pm (11.13 pm Italian time) a McDonnell Douglas MD-11 cargo plane crashed at the International Airport of Louisville, in Kentucky (USA), during take-off. The collision with an industrial area south of the airport hub caused a giant fireball and several explosions which in turn caused at least 12 victims. According to initial reconstructions, the left engine would have detached and that wing would have caught fire, causing the tragic end of the aircraft. The aircraft’s black boxes were recovered and sent to Washington for analysis by the National Transportation Safety Board. But what could be the causes from a technical point of view? To try to clarify, we interviewed Nicolò Fatai, airline pilot and popularizer.
Nicolò, from a technical point of view, what could be the causes behind the engine detaching from the plane during take-off? And was this what started the fire?
Hi Stefano, thanks for the invitation. Before answering questions, I would like to express my deepest condolences to the victims and their families involved in this tragic accident.
It’s still too early to know for sure what happened. An engine failure on takeoff is an event extremely rare and can be caused by several factors. And it doesn’t have to be something explosive or sudden: sometimes it can come from microfractures or material fatigue that goes undetected during inspections. Other times it can be the result of a human error in maintenance, as happened in theChicago accident of 1979when a DC-10 lost its left engine because it had been reassembled incorrectly. Then there are cases in which a foreign object or debris on the track, for example, can enter the engine or hit the structure that supports it, the so-called pylon.
If the engine has really detached, as it seems in this case, it is very likely that the fire started there: the wing contains the fuel and the detachment of the engine can break pipes and fuel lines, causing leaks of jet fuel which immediately catch fire. To find out exactly what happened, official investigations and black box data will be needed.
Then many people asked why the plane decided to take off even though one wing was on fire and one engine had come off. Because it seems paradoxical but in these cases you will confirm that once a certain speed is exceeded the plane can no longer cancel take-off, right?
That’s right, in fact before take-off, the pilots carry out the takeoff performance calculationswhich take into account various factors: aircraft weight, runway length, temperature, wind, altitude and aircraft configuration. From these calculations a fundamental parameter is obtained, the decision speed, called V1. Up until V1, pilots can still abort takeoff and brake safely on the runway. Once you pass V1, however, it is no longer possible to stop without risking going off the track. For this reason, if a failure — even a serious one, such as a fire or the loss of an engine — occurs after V1, the correct procedure is continue takeoffbecause the remaining runway is no longer enough to stop the plane.
In the case of the MD-11, it is very likely that the aircraft had already passed V1 when the problem occurred. At that point, even if it may seem like it counterintuitive, the safest decision remains take off And manage in-flight emergencies.
Finally I have one last question: is there a possibility that it was a human error?
Certain. As I said before, i engines they are among the most complex parts of an aircraft, and in aviation there are rigorous procedures both in the cockpit and in ground maintenance precisely to avoid and “intercept” errors first that they turn into something more serious. It should also be remembered that, unfortunately, the majority of aviation accidents originate from human error, be it related to the pilot, maintenance personnel or ground control procedures. This does not mean that it can be taken for granted that it happened in this case too, but it is a possibility that investigators always take into consideration from the beginning.
