Although some helicopters have wheels, most have skid type landing gear. One of the biggest problems with skids is how to easily move the helicopter around on the ground. Attaching ground handling wheels to the skids is an option that works well for a small helicopter like the Robinson R22. However, for larger turbine helicopters the wheels are bigger and not very convenient to carry with the helicopter. Moreover, it normally requires more than one person to maneuver a heavy helicopter on wheels. As such, the helicopter dolly is a common option.
A helicopter dolly is a wooden, sometimes metal, platform with wheels that a helicopter can land on. Once the helicopter is on the dolly it can be towed with a tractor or tug. Landing on a dolly can be hazardous and there are some pilots that do not think it’s worth the risk. The danger comes from the difficulty seeing the skid gear while having to precisely set the helicopter on the platform. Some dollies do not have a lot of extra room so even a little drift at the last minute can cause one skid to miss the platform and the helicopter to roll over. Even if the pilot realizes this and attempts to abort there is the possibility that the skid will get caught on the edge, also causing a roll over. These types of accidents have all happened. There was even a case where the pilot did a nice dolly landing, rolled the engine to idle and then realized the dolly wheels were not chocked. The dolly started rolling and stopped when the helicopter’s nose hit a parked tug.
The pilots that support dolly landings say that with the proper mindset and approach, dolly landings are safe. For example, taking your time with the set down, not being nervous and getting instruction. Additionally, the dolly should be into the wind and large enough to accommodate the helicopter while allowing room for error.