This Southwest came in as an emergency last month. I don't recall the specifics, but there were no injuries and the aircraft landed safely. Here we see the LAX ARFF trucks inspecting the aircraft with thermal cameras for a possible fire or, more likely, hot brakes, a probable scenario when an aircraft lands overweight or at a higher than usual speed. An overweight landing can occur when an aircraft has to return for landing shortly after departing for a long-distance flight and as a result still has a large fuel load onboard; many aircraft can actually take off at a higher weight than they can land, as they are designed with the expectation that they will burn off fuel during the flight, and not all aircraft have the ability to dump fuel. A high-speed landing may happen when the aircraft experiences difficulties with the wing flaps or leading edge slats. Both of these are aerodynamic devices on the wings that allow the aircraft to take off and land at slower speeds by increasing the amount of lift that the wings can produce. Because flaps and slats also increase the aerodynamic drag, they are retracted after take off to allow higher cruise speed and reduced fuel burn, and then extended again before landing. If the airplane takes off and they can't be retracted, the flight will usually return because the added drag will slow the plane down and increase the required fuel for the flight, likely to the extent that the fuel onboard will not be sufficient. The more common scenario that we see is a flight that is arriving and discovers that they are unable to extend the flaps and/or slats, perhaps due to a hydraulic failure. This will result in the aircraft landing at a higher speed than normal, which may lead to hot brakes. Hot brakes can be an issue because at sufficient temperatures the brakes can actually catch fire.
