This morning local time, a South Korean passenger plane carrying 181 people collided and caught fire. According to South Korea's Ministry of Land, Infrastructure, Transport and Tourism, the accident was caused by the plane hitting a flock of birds. How did the plane hit the birds? When is it most dangerous for a plane to hit a flock of birds? Let’s listen to the analysis of Wang Yanan, an aviation expert at Beihang University. According to Wang Yanan, aircraft collisions with birds are a type of accident that has seriously threatened commercial aviation safety in recent years.
However, in recent years, bird collisions with aircraft rarely directly lead to tragic flight accidents and heavy casualties, because modern civil aircraft are designed for bird collisions.
For example, the cockpit of the aircraft and the leading edge of the wings are designed to be anti-collision; even if the engine loses thrust in a collision, it can still rely on the power of another engine to maintain a considerable flight time. Therefore, it is difficult for a bird to collide with an airplane directly cause major casualties.
However, there is one type of situation that is more demanding for pilots to deal with, that is, when the aircraft is about to land or has just taken off, it is at a low altitude and low speed.
When the aircraft lowered its landing gear and prepared to land this time, the speed and altitude of the aircraft were probably very low. A sudden impact with the birds was likely to cause some parts of the landing gear to malfunction or deform, making it impossible to lower them. At this point, the aircraft can only touch the runway without landing gear. This means that after the aircraft touches the runway and has relatively large kinetic energy, the pilot cannot control the direction of the aircraft through the landing gear and brakes.
The aircraft fuselage and engines are in direct contact with the runway
Engine thrust reverse may not work properly
Experts said that in the video, the plane's spoilers, including the wings, were not fully deployed for deceleration, which is also a problem worthy of attention. Was it due to some kind of malfunction caused by hitting the birds, or was it because the pilot's control did not allow these deceleration systems to work, which caused the aircraft's speed to remain high and eventually overshot the runway and hit an obstacle. This will need to be clarified later in the investigation.
An airplane without landing gear
Direct contact with the runway is extremely dangerous
It is very dangerous for an aircraft to directly contact the runway without landing gear. At this time, the pilot should try to reduce the speed of the aircraft to a reasonable level, and at the same time, try to control the corresponding position of the contact point between the aircraft and the runway, so as to leave sufficient space for the aircraft to decelerate and buffer. From the video, it was not confirmed whether the plane landed on the runway or a taxiway. All in all, the space in front of the plane is very limited.
Plane hits birds
Will leave very obvious traces
Wang Yanan said that when birds hit an aircraft, they usually leave obvious traces, and parts will be deformed at the point of impact, such as dents. Around the impact point, there will be remains of bird carcasses, blood stains, feathers, etc. Even after the plane has disintegrated, traces will still remain. Investigators can easily determine whether the aircraft was struck by a bird through traces left at the scene.
The aircraft's attitude changes after landing
Paving the way for impact
Experts said that according to the video, when the plane was about to touch down, the engine on one side suddenly spurted out flames. This may indicate that the point where the plane was hit by the birds was not only the landing gear, but also the engine on one side. In this case, the thrust of one engine suddenly decreases sharply, which will cause the aircraft's attitude to change drastically at low speed. After the aircraft touched the runway, its attitude was extremely complicated. This paved the way for the plane behind to overshoot the runway and cause a violent impact.
In the accident investigation, there are two directions of greatest concern.
The first is what kind of danger did the plane encounter when it was about to land? Is it the collision of a flock of birds, or the collision of a few flying birds? What was the location of the impact? How is the intensity? What kind of failure caused it?
In addition, when the aircraft encountered such a serious situation, whether the pilot handled it appropriately. Whether pilots can achieve better results through correct and appropriate handling.