Aviation law provides rules for operating airplanes and other aircraft, and regulates airline flights. Airport construction, operation, and maintenance are also governed by aviation law. If you are a pilot, aviation law tells you the proper take-off and landing procedures, what to include in flight plans and where to file them, what altitudes to fly at, and whether instrument-only flight is possible. If there is an aviation accident, the person responsible—whether it's the baggage handler, the airplane mechanic, the flight controller, or the pilot—is often easily identified by their failure to follow specified flight procedures. There can be many factors in an aviation accident, so an aviation lawyer is often very helpful.