QNH altimeter setting: This means indicated altitude above mean sea level or the al timeter reads the elevation of the airport when the aircraft is on the ground. QNH is given to aircraft prior to takeoff as was the case for many aircraft. It is also given in flight so that the pilot may determine whether given flight levels provide adequate terrain clearance. In most areas, these are added to weather broadcasts. QNH altimeter settings are also given to air craft on approach clearances or on entering the traffic circuit. QFE altimeter setting: This setting indicates the height above the station, that is, the altimeter will read0when the aircraft lands at the station. These are normally made avail able in the landing instructions on request from the aircraft. QNE altimeter setting: QNE is always set with 29.92 inches of mercury hg (1013.25 millibars), and results in the altimeter indicating height above a standard datum plane or pressure altitude. In the United States it is used for all flight above 18,000ft MSL. This altitude is called a transition altitude. Many nations use the 29.92 inches hg/10l3.25mb altimeter setting for all flights above the transition altitude of the departure or arrival airport. However, many countries also have different altitudes where the setting may be changed. For example, the transition altitude for Frankfurt, Germany, is 5000ft (QNH), and for Nice/Cote D＇ Azure, France, it is 2000 ft. When an aircraft＇s vertical position is at or below the transition altitude, ICAO re quires altitude to be expressed QNH. When the aircraft is at or above the transition level, the plane＇s altitude is expressed in terms of flight levels (QNE). A pilot flies an aircraft at the flight levels specified for the various airways (or flight levels corresponding to the mag netic track if it is off the airway system) as shown in the en-route aeronautical publications. Of course, a pilot never accepts a flight level which does not allow for adequate terrain clearance.5.According to the passage, we can safely say （ ） .