Based on flight levels, stratosphere refers to flying _______.

相关题目

• Before flight, pilots must have at least _______ hours rest time
• PAR is superior to ASR in that it can provide _______ .
• _______ radar service，the radar controller should inform the pil
• If an aircraft’s identification is lost before or during a hand-
• When an ASR procedure terminates at less than 2 miles from touch