What type of aircraft incidents may involve fuel spills?

Fuel spills can occur in a variety of aircraft incidents, making the most comprehensive answer "All of the above."

In the case of taxiway collisions, aircraft may be damaged, leading to ruptures in fuel tanks or fuel lines, which can result in spills on the airport surface. Aircraft crashes present a similar risk, as the impact can cause significant structural damage, leading to fuel leakage from the fuel system of the aircraft. In-flight emergencies can also lead to fuel spills; for example, if an aircraft encounters a serious issue that requires it to return to the airport, it may need to dump fuel to reduce weight for landing, which can spread fuel over the ground near the airport.

Therefore, each incident type mentioned has the potential to involve fuel spills, highlighting the importance of comprehensive fire safety measures and emergency response protocols in airport firefighting.