biofuel initiative. KLM has made the first commercial flight with biofuel in 2009. There are projects on electric aircraft, and some of which are fully operational as of 2013. Call signs Each operator of a scheduled or charter flight uses an airline call sign when communicating with airports or air traffic control. Most of these call-signs are derived from the airline's trade name, but for reasons of history, marketing, or the need to reduce ambiguity in spoken English (so that pilots do not mistakenly make navigational decisions based on instructions issued to a different aircraft), some airlines and air forces use call-signs less obviously connected with their trading name. For example, British Airways uses a Speedbird call-sign, named after the logo of one of its predecessors, BOAC, while SkyEurope used Relax. Personnel The various types of airline personnel include flight crew, responsible for the operation of the aircraft. Flight crew members include: pilots (captain and first officer: some older aircraft also required a flight engineer and/or a navigator); flight attendants (led by a purser on larger aircraft); In-flight security personnel on some airlines (most notably El Al) Groundcrew, responsible for operations at airports, include Aerospace and avionics engineers responsible for certifying the aircraft for flight and management of aircraft maintenance; Aerospace engineers, responsible for airframe, powerplant and electrical systems maintenance; Avionics engineers responsible for avionics and instruments maintenance; Airframe and powerplant technicians; Electric System technicians, responsible for maintenance of electrical systems; Flight dispatchers; Baggage handlers; Ramp Agents; Remote centralized weight and balancing; Gate agents; Ticket agents; Passenger service agents (such as airline lounge employees); Reservation agents, usually (but not always) at facilities outside the airport; Crew schedulers. Airlines follow a corporate structure where each broad area of operations (such as maintenance, flight operations (including flight safety), and passenger service) is supervised by a vice president. Larger airlines often appoint vice presidents to oversee each of the airline's hubs as well. Airlines employ lawyers to deal with regulatory procedures and other administrative tasks. Trends The pattern of ownership has been privatized since the mid-1980s, that is, the ownership has gradually changed from governments to private and individual sectors or organizations. This occurs as regulators permit greater freedom and non-government ownership, in steps that are usually decades apart. This pattern is not seen for all airlines in all regions. Many major airlines operating between the 1940s and 1980s were government-owned or government-established.