Hydraulic gear systems frequently have gear levers with a third “off” position that mechanically locks the gear in the up position without providing hydraulic pressure to keep it up. While various plugins or scripts have been used to animate this type of lever in the cockpit, interaction with X-Plane was always clumsy and did not necessarily work with commands.

The goal of the new gear datarefs is to enable a consistent user experience both with VR and traditional hardware

Gear lever with “off” position

To enable the new behavior, check the “hydraulic LDG gear with Up/Off” option in Plane Maker on the hydraulic systems settings.

The following datarefs are new:
sim/cockpit2/controls/gear_handle_animation float y ratio
Gear handle position as float for lever animation. 0 is up, 1 is down, 0.5 is off (for planes that have that).
sim/cockpit2/controls/gear_handle_request int y enum
Gear handle request. 0 is up, 1 is down, -1 is off.
sim/cockpit2/controls/gear_handle_downlock_release int y boolean
Gear handle downlock release. If this is 1, the gear handle can be moved to up even if the squat switch reports weight on wheels

The commands sim/flight_controls/landing_gear_off and sim/flight_controls/landing_gear_downlock_release are also new.

You can use the animation dataref directly, and it will update the request enum if you are close enough to 0, 0.5 or 1 position. This is especially useful for large handles that have to act naturally in VR.

If you use the commands, the animation dataref is smoothly driven to the 0, 0.5 or 1 position. This is important if external cockpit hardware is used.

If you use the old int dataref, it will update the status to 0 or 1 (no way to achieve off with the old dataref) and the animation dataref will follow smoothly. This ensures that all legacy aircraft and also all new aircraft with no “Off” position work correctly.

Gear lever mechanical lock

Almost all retractable gear systems employ squat switches, that prevent gear retraction on the ground. This corresponds to the “gear can retract on ground” setting in Plane Maker, which would be unchecked for most aircraft.

The new setting “LDG gear lever dnlock” can be checked to configure the behavior of the gear lever in the cockpit. With this option checked, the gear lever in the cockpit is physically arrested in the down position and cannot be moved while the squat circuit is open. This can be overridden with the downlink release command sim/flight_controls/landing_gear_downlock_release.
With this option not checked, the landing gear lever can be moved, but simply won’t actuate the gear when the squat circuit is open. That is the same behavior as X-Plane 11, and appropriate for most small general aviation planes.



  • Aircraft Development

Article type:

  • Tech Note


  • X-Plane 12