Manual

slow speeds. Think in terms of knots andnot mph.Airspeed is the velocity of an aircraftrelative to the surrounding air mass. It isnot an absolute indication of the aircraft’sspeed over ground. A reading of 450knots does not necessarily mean that theaircraft is travelling 450 nautical miles anhour between points on the ground.Your speed is displayed in KIAS (KnotsIndicated Air Speed). The primarydifference between IAS (indicatedairspeed) and TAS (true airspeed) is airdensity. Pilots use indicated airspeedbecause it is a constant as opposed totrue airspeed which is affected by bothambient temperature and altitudevariations. Because air density at higheraltitudes is less than that found at sealevel, an aircraft’s indicated airspeed willdecrease as altitude increases.Therefore, an aircraft flying at 30,000 feetwith an indicated airspeed of 350 knots istravelling much faster than an aircraft at5,000 feet with the same indicatedairspeed.A mach number is the speed of youraircraft in relation to the speed of sound.An aircraft flying at the speed of sound issaid to be travelling at mach 1. The sameaircraft flying at twice the speed of soundwould be travelling at mach 2. Above30,000 feet, pilots manoeuvre their aircraftusing mach numbers instead of indicatedairspeed.As you can see by the following chart, theindicated airspeed of an aircraft travellingat mach 1 varies considerably due toaltitude. An aircraft flying at sea level hasto be doing 661 KIAS to break the soundbarrier. The same aircraft at 60,000 feet,however, would only show an indicatedairspeed of 198 KIAS.You can also use the mach number to geta rough idea of your aircraft’s groundspeed. Simply multiply the mach numberALTITUDE KIAS AT MACH 1at 0 ft:661 KIASat 10,000 ft:548 KIASat 20,000 ft:450 KIASat 30,000 ft:360 KIASat 40,000 ft:312 KIASat 50,000 ft:251 KIASat 60,000 ft:198 KIASby 10. This is the approximate distanceyour aircraft is travelling in nautical milesper minute. For example, at mach 1 theaircraft is travelling 1 x 10 or 10 nauticalmiles per minute. At mach 2, this distancewould be doubled (2 x 10= 20).Angle of Attack (AOA)Angle of Attack is one of those conceptsthat flight instructors can describe, define,and demonstrate for hours. But a studentpilot will either grasp the concept withinthe first few minutes or he won’t get it nomatter how long his instructor raves. Thedefinition of Angle of Attack in its mostsimplistic form is: the angle (measured indegrees) at which the wing surface of anaircraft cuts into the relative wind. That’sall there is to it and yet it is one of themost difficult concepts for novice pilots tounderstand.Basically, AOA is the difference betweenthe aircraft’s flight path and the “chordline” of the wing. In level flight, the “chordline” of the wing is facing directly into theairflow. When climbing, the “chord line” ofthe wing is pitched upward relative to theairflow. With its nose and wing pitched up,the aircraft is said to have increased itsangle of attack. The reverse is true whendiving.Angle of Attack is not the same thing aspointing the nose at a certain tick mark onthe climb ladder and it has nothing to dowith the position of the horizon. (Pointingthe nose of the aircraft up or down iscalled aircraft attitude.) Aircraft attitude