Final answer:
Aerospace engineering is the field related to the elements that solely support flightline activities, encompassing aspects of mechanical engineering, avionics, and specialized ground support.
Step-by-step explanation:
The element that supports flightline activities solely is typically related to the field of aerospace engineering. Flightline activities refer to the operations that take place on the flight line, which is the area of an airfield where aircraft are parked, serviced, and ultimately prepared for takeoff and landing. Specialists responsible for ensuring that this area operates smoothly might be concerned with aspects of mechanical engineering, avionics, aircraft maintenance, and ground support. Due to the specificity of the activities and the equipment involved, such as tugs, fuel trucks, and other specialized vehicles, the support for flightline would be dependent on personnel trained in how to use and maintain these various systems and machines tailored to aviation requirements.
Helium is a lighter-than-air gas, which means it is less dense than the surrounding air. When it is filled in large balloons or airships, it provides the necessary buoyancy to make them float and enables air travel.
Helium is commonly used for flightline activities such as hot air balloons, blimps, and helium-filled weather balloons for atmospheric research and data collection.