Which condition prompts the operator to maintain control on the deadman switch during refueling?

Maintaining control of the deadman switch during refueling is critical for safety reasons, particularly in scenarios where high pressure could lead to a shut-off condition. The deadman switch serves as a safety feature that ensures the refueling operation can be immediately halted if the operator loses control or attention. In the context of high-pressure scenarios, the operator must be vigilant, as excessive pressure can lead to equipment failure or hazardous situations, prompting the need to keep the deadman switch engaged. This action prevents automatic shut-off mechanisms from being triggered prematurely due to rising pressure, ensuring that refueling can be conducted safely and without interruption until desired levels are achieved. Control over the deadman switch directly relates to managing operational safety and preventing mishaps associated with high-pressure conditions.