Aircraft Owners and Pilots Association, non-profit political organization serving the interests of its members to promote the economy, safety, utility, and popularity of flight in general aviation aircraft.Discovered back to the fifties, the rule mandates a constant crossectional area as measured at stations along the centerline of the aircraft.
The face is calibrated in 'feet MSL' and an adjustment ("Kollsman Window") that enables correcting for local atmospheric pressure, which is in turn given as 'inches of mercury' (29.92 being the so-call "Standard Atmosphere). The chord is simply the straight line that connects the leading edge of the wing with the trailing edge (longest dimension front-to-back).
The relative wind, not so simply, is the direction from which the air appears to be coming.
In level flight, the relative wind strikes the plane horizontally from straight ahead.
During ascent (or descent), the relative wind comes from above (or below) the plane.
At the radar scopes you have 'departure' controllers, 'enroute' controllers, and 'approach' controllers.
The vast majority of airports do not have control towers.Most use Unicom or CTAF (Common Traffic Advisory Frequency) to exchange information among the pilots flying in the pattern. ("Caldwell traffic, Cardinal Niner One Four, wing-up, turning right base for Runway Three Zero, behind the Cherokee.") Automatic Terminal Information Service (pronounced ATE-is), a transcribed radio message that gives up-to-date advisories about conditions and procedures at a particular airport.(Altitude) Above Ground Level, where all aircraft must fly. Distinguished from MSL, (above) Mean Sea Level, which is what an altimeter measures, and can indeed be negative. In 1980, a friend of mine set one of aviation's lesser known world records: Low-Altitude Endurance, flying at -200 feet MSL (+50 feet AGL) for over five hours, in Death Valley (now her husband plans to set the high-altitude submarine record with a one-man submersible in Peru's Lake Titicaca).To determine altitude AGL -- the most vital measurement aloft -- the pilot must know: (a) the plane's altitude MSL, (b) the plane's geographical position, and (c) the elevation (MSL) of the ground (the G in AGL) at that location.(statute miles per hour) same as automobiles and trains.Marketing psychology doubtless played a role: To say your sedan goes "100 mph" is more exciting than "87 kts" -- much as $100 is preferred for a prize, while $99.95 works better as a price.Alpha, Bravo, Charlie (shar-lee), Delta, Echo, Foxtrot (often shortened to Fox), Golf, Hotel, India, Juliet, Kilo, Lima (pronounced as the city not the bean), Mike, November, Oscar (oss-kah), Papa, Quebec (kay-beck), Romeo, Sierra, Tango, Uniform (oo-nee-form), Victor (vik-tah), Whiskey, X-ray, Yankee, Zulu.