To create a multi-leg movement using air transport, what is the first step?

In the context of creating a multi-leg movement using air transport, initiating the process with a house bill is fundamental. A house bill is a critical document that outlines the details of the shipment, including its identification, the origin and destination, and the specifics about the consignor and consignee. By starting with the house bill, you ensure that all necessary information is captured, which lays the groundwork for creating subsequent legs of the transport.

Once the house bill is generated, it facilitates the execution of the air leg, allowing for a structured and traceable transport operation. This step is essential as it signifies the beginning of the transportation process and aligns all stakeholders involved in the air transport logistics.

The other options, while related to aspects of logistical processes, do not represent the initial step in creating a multi-leg air movement. Filling out an execution report refers to documenting actions that have already been taken, whereas creating a route template and notifying the airline would normally follow the creation of the house bill and be dependent on the information contained within it. Thus, the house bill serves as the kickoff point for planning and executing air transport movements effectively.