Which phrase is NOT allowed when directing ground traffic?

The phrase "The field is yours" is not permitted when directing ground traffic because it is vague and could lead to misunderstandings or unsafe situations. Ground traffic control requires precise instructions that eliminate ambiguity. Clear and specific commands help ensure that pilots understand their movements and maintain safe distances from other aircraft and obstacles.

In contrast, the other phrases provide clarity regarding what actions pilots should take on the airport's surfaces. Statements like "Cleared on all surfaces," "Proceed on all runways/taxiways," and "Airport 1, proceed on runway #." give pilots clear directives that they can follow without confusion, thus promoting safe operation on the airport grounds.