Abstract: Mobile platform units for separate selective engagement with the normal ground contact elements of aircraft undercarriage components (inclusive of wheels and tires, etc.) for distributing the usual highly concentrated loadings thereof over a greater ground contact area. The mobile units have a platform supported above ground level by rolling support components that may comprise a plurality of rotatably mounted rollers, or wheels, and/or endless belt tracks disposed thereabout to collectively provide a total ground contact area which is greater than that of the aircraft ground contact element being supported. Ramp components of resilient construction are hinged to the platform in a manner providing a downturned inwardly disposed leg that is adjacent to the rotatably mounted rollers, etc. when the ramp is in a down position whereby the weight of an aircraft on the resilient ramp moves the downwardly turned leg to an interfering position providing braking action for the units.