Flameout is jet engine failure when the flame that normally burns continuously during operation goes out. Without heat from the flame, the engine can no longer provide propulsion. Aircraft will not fall out of the sky immediately when a flameout occurs, but it can pose a risk if not addressed. It is usually possible to restart the engine and restore functionality.
Aircraft powered by jet engines typically have multiple engines to create not only more power, but some redundancy. In the event one engine experiences a flameout, a situation that can occur in a variety of circumstances, the other engines can compensate. Once the pilot restores function to the failed engine, the plane can stabilize and continue flight. Autopilot systems monitor engine functions and can alert pilots to problems as well as performing the necessary calculations to keep a plane under control when one or more engines fails.
Jets rely on a continuously burning flame to function as air and fuel move through the engine. In a flameout, it dies, and the pilot must restart the engine to get the flame going again. One possible reason for this is mechanical obstruction in the engine, usually caused by contact with a foreign object like a bird or volcanic ash. The air/fuel mixture can also be a culprit, as too much fuel can douse the flame. Physical damage can be another issue, as can inadequate oxygen supplies.
Inclement weather is a common cause of flameouts. Severe rain, snow, and ice can potentially put out the flame in an engine, even with protective covering and other measures intended to limit exposure to the elements. This is a particularly high risk when engines operate at low speeds, as may occur during descent or once a plane gets to cruising altitude. During these periods of the flight, pilots remain alert to early warning signs of problems with their engines so they can take appropriate evasive action if necessary.
In the event of a flameout, safety systems kick in to stabilize the plane as much as possible. Sometimes it is not possible to restart the engine and the plane may need to make an emergency landing with the remaining engines. Other instances, like those involving multiple engine failures or problems with other systems in the plane, can result in crashes. After a crash investigators carefully evaluate all available material to determine what happened and search for possible methods to avoid such incidents in the future.