Which phrase indicates that an ATC clearance does not include the altitude?

When an ATC clearance is given as "cleared as filed," it refers to the pilot being authorized to proceed with the flight plan that has been filed, but it does not specify an altitude for the flight. This means that while the pilot is cleared to follow the route as planned, it is up to the pilot and ATC to determine the altitude, which may need to be coordinated separately.

In contrast, other phrases like "cleared for an approach," "cleared for takeoff," and "cleared to land" typically come with specific altitude instructions. For instance, "cleared for an approach" often includes altitude restrictions relevant to the final approach, while "cleared for takeoff" implies the pilot should follow predetermined climb out protocols, and "cleared to land" generally indicates that the aircraft should descend to the runway. Each of the latter phrases is accompanied by explicit instructions on altitude, making them unsuitable for indicating a lack of altitude information.