What is hold mode?
The hold mode is a control state in which a system preserves its current condition—such as altitude, heading, position, or torque—until a new command arrives. It acts as a deliberate pause that prevents automatic changes and allows for safe, orderly transitions.
Basic concept of hold mode
Hold mode describes a deliberate stabilizing state used across various technologies. By maintaining a fixed value or pose, it reduces drift, simplifies sequencing, and gives operators time to assess and adjust before proceeding.
Aviation: hold mode in the skies
In aviation, hold mode helps manage flight paths and delays, both in the cockpit and on the ground. Autopilots provide hold functions, and published holding patterns let aircraft wait for clearance without looping uncontrollably.
Here are the common hold-mode functions pilots rely on.
- Altitude hold (ALT HOLD): The autopilot maintains the aircraft at a specified altitude.
- Heading hold (HDG HOLD): The autopilot preserves a selected magnetic heading or track.
- Localizer/glideslope hold (LOC/GS HOLD): The system trims to follow the localizer or glideslope during instrument approaches.
- Holding pattern: A racetrack maneuver used to delay descent or align with the runway while awaiting clearance.
Together, these hold modes enable stable flight, reduce pilot workload during busy phases of flight, and help ensure safe sequencing for landings and departures.
Common misunderstandings about hold mode
Hold mode is sometimes mistaken for a complete stop or a manual “freeze” of all activity. In reality, hold mode is a controlled state where specific parameters are preserved while other systems may remain active or be commanded to resume when conditions allow.
Medical, industrial and robotics hold modes
Beyond aviation, hold mode appears in medicine, manufacturing, and robotics to pause processes, prevent drift, and ensure safety and precision. It provides a predictable transition point between actions and helps prevent unintended changes during alarms or disturbances.
Examples include:
- Infusion pumps: Hold or pause mode temporarily stops drug delivery during alarms, repositioning, or changes in patient status.
- Robotics and automation: Position hold or torque hold maintains the end-effector’s pose or joint torque when disturbances occur.
- Industrial control systems: A hold state preserves a sensor value or actuator position until a deliberate command updates the value.
In these domains, hold mode reduces risk, protects patients and equipment, and provides safe opportunities to review and adjust before resuming normal operation.
Exiting hold mode
To resume active control, operators typically issue a new target, switch back to normal operation, or release the hold control. The exact steps vary by system, but the goal is the same: re-establish a defined, controllable state.
Common steps across domains include:
- Command a new target or re-engage automatic control
- Confirm safety and readiness for the change
- Monitor feedback and adjust as necessary
Always consult the device or system manual for model-specific hold mode behavior and exit procedures, as details can differ between equipment and industries.
Summary
Hold mode is a versatile concept that functions as a stabilizing pause across aviation, medicine, manufacturing, and robotics. By preserving current values or poses, it helps ensure safety, improve predictability, and enable smooth transitions back to active control when conditions allow.
