Final answer:
The question deals with engineering, and more specifically, aviation engineering, inquiring about the airspeed limit for engaging the HVR VHLD mode in aircraft operation. Without the specific aircraft model, an exact airspeed value cannot be provided, but it would be detailed in the aircraft's operating handbook.
Step-by-step explanation:
The subject of the question is Engineering, specifically relating to aviation, as it refers to the High Velocity Retreat (HVR) Variable Helix Landing Deceleration (VHLD) mode, which is a term associated with the operation of certain aircraft systems. To engage the HVR VHLD mode, the airspeed must be below a certain threshold, which is specified in the aircraft's operating handbook or by the manufacturer. However, without specific information on the aircraft model, a precise airspeed value cannot be given. Generally, such operational limits are put in place to ensure that the aircraft can engage in certain maneuvers or modes of operation safely and without exceeding the structural limits of the airframe or the capabilities of the onboard systems.