What happens if the onboard foam pump is non-functional?

When the onboard foam pump is non-functional, the application of foam is indeed limited because most modern fire apparatus rely on these pumps to mix and dispense foam effectively. Without a functioning foam pump, the ability to deliver the foam at the required concentration and pressure diminishes significantly. This situation usually necessitates finding alternative methods to apply foam, which may not be as efficient or effective given the circumstances preventing the use of the onboard system.

While it might be possible to apply foam manually or use alternative foam sources, these options can complicate the firefighting effort and may not provide the same level of efficiency or coverage that a properly functioning foam system would. Therefore, the correct answer reflects the reality that the non-functionality of the onboard foam pump inherently constrains the operational capabilities regarding foam application.