Which is NOT a method for resupplying foam?

The correct choice indicates a method that is not typically used for resupplying foam. Using a hose to siphon is often impractical and inefficient for resupplying foam in an aircraft rescue and firefighting context. Siphoning requires a certain elevation difference and can lead to contamination or loss of foam properties during the transfer process.

In contrast, the other methods—overhead gravity, transfer from a tender using a pump, and refilling directly from a 5-gallon container—are established and effective techniques for ensuring a reliable and consistent supply of foam. Overhead gravity allows for a controlled and steady flow of foam, which is beneficial in maintaining operational readiness. Transferring foam from a tender using a pump ensures that the foam is delivered at pressure to meet the demands of the firefighting situation. Refilling directly from a 5-gallon container provides a straightforward and manageable way to replenish foam supplies.

These other methods emphasize the importance of functionality and reliability in foam resupply operations, critical for effective firefighting and rescue missions.