Pronunciation: [ˈe͡ə spˈiːd] (IPA) 
The correct way to write "air speed" is /ɛr spid/. The first part, "air", is pronounced with the vowel sound /ɛr/, which is written with the letters "e" followed by "r". The second part, "speed", is pronounced with the vowel sound /iː/, which is written with the letters "ee". Remembering the correct spelling of "air speed" is important in aviation as it measures the speed at which an aircraft is moving through the air.
Air speed refers to the speed at which an object or a vehicle is moving through the air. It is the rate at which an aircraft or any other airborne object is traveling relative to the air mass in which it is flying. This measure is essential in aviation as it helps pilots determine their velocity in relation to the air surrounding them, which in turn aids in various aspects of flight control and navigation.
Air speed is typically measured in knots, with one knot being equivalent to one nautical mile per hour. It is distinct from ground speed, which is the actual velocity of the aircraft relative to the Earth's surface. The difference between air speed and ground speed lies in the presence of wind. If there is no wind, the air speed and ground speed will be identical, but when winds exist, the two speeds can vary significantly.
Pilots need to pay close attention to air speed as it directly influences the performance and safety of an aircraft. It affects factors such as takeoff and landing distances, fuel consumption, stall speeds, and maneuverability. Accurate air speed measurements are crucial for determining critical parameters like Mach number, indicated airspeed, equivalent airspeed, and true airspeed. Air speed indicators, instruments installed in aircraft, display the current air speed to pilots, allowing them to make informed decisions and adjustments during flight to ensure a smooth and efficient journey.
The etymology of the term "air speed" can be traced back to its individual components: "air" and "speed".
The word "air" comes from the Old English word "ær", which ultimately derives from the Proto-Germanic language. It is related to the Old High German word "ār" and the Dutch word "lucht", all of which refer to the substance that surrounds the Earth and is predominantly composed of nitrogen, oxygen, and other gases.
The term "speed" has its roots in the Old English word "spēd", which is related to the Old Norse word "spjar" meaning "success" and the German word "spöten" meaning "to advance quickly". The word "speed" in English refers to the rate at which something moves or operates.
