What is the least desirable method of resupplying an apparatus with foam?

The method of resupplying an apparatus with foam using 5-gallon containers is considered the least desirable due to several factors. Firstly, this method is labor-intensive and time-consuming, as it requires manual handling of multiple heavy containers, which can lead to fatigue during emergency operations. The process can be inefficient, as each transfer takes time away from active firefighting efforts.

Additionally, filling from small containers may not provide the necessary volume of foam needed for larger fires or incidents, limiting the effectiveness of the firefighting operation. In contrast, other methods such as vehicle to vehicle or utilizing mechanical pumps offer more rapid replenishment of foam, allowing for sustained firefighting efforts without significant downtime.

Overhead gravity filling may also be more efficient than using small containers, enabling quicker replenishment without the need for extensive manual labor. Therefore, while resupplying with 5-gallon containers is feasible, it lacks the efficiency and speed required during critical fire suppression situations, making it the least desirable method in the context of airport firefighting operations.