I'll walk you through the important ones — Page 632, Lesson 733

We're looking at a batch of practice questions and answers here, so let's work through the key techniques and concepts they're testing. I'll walk you through the important ones. First, question 46 and 52 both use the CRP-5 computer. The technique is: in the airspeed window, you set the ambient temperature against the Mach number index. Then, against a value on the inner scale—which is the CAS or Mach number scale—you read off the local speed of sound, the LSS, on the outer TAS scale. In question 46, with +5°C set against the Mach index, and 10 on the inner scale, you read 650 knots on the outer scale. That's the LSS at that temperature. Question 47 is a simple compass calculation. The formula is C ± D = M ± V = T. That means Compass plus or minus Deviation gives Magnetic, then plus or minus Variation gives True. Here, 244° plus 11° of deviation gives 255° magnetic, then minus 8° of variation gives 247° true. Question 48 combines two steps. First, calculate TAS from the given information—and don't forget compressibility! That gives 481 knots. Then, in the airspeed window, set -65°C against the Mach number index. Against the TAS of 481 on the outer scale, read the Mach number on the inner scale—M 0.855. Question 49 is about compass behavior during acceleration errors. During a deceleration, the direct reading compass shows an apparent turn towards the further pole. In the northern hemisphere, that's an apparent turn towards the south; in the southern hemisphere, towards the north. Accelerations are exactly opposite—they show apparent turns towards the nearer pole. Question 51 defines the magnetic terms. Variation is the angular difference between true north and magnetic north. Deviation is the angular difference between magnetic north and compass north. Dip is the angle between the horizontal component—called H, or the directive force—of the earth's magnetic field, and the total magnetic force, or intensity, of the field. An isoclinal is a line joining points of equal dip on a chart. The aclinic line indicates zero dip and is also called the magnetic equator. Question 53 explains why Mach number rises dramatically in a climb. Due to density error, TAS increases even at constant CAS. Meanwhile, the LSS—being temperature-controlled—decreases. Since Mach number equals TAS divided by LSS, an increase in TAS and a decrease in LSS must give a marked increase in Mach number. A descent reverses those speed changes. Question 54 covers basic magnetism: like poles repel, unlike poles attract, and lines of flux run from the red north-seeking pole to the blue south-seeking pole. Question 55: double integration means the second stage of integration—here, distance along the local meridian. Question 56: a solid-state gyro refers to the ring laser gyro used in inertial reference, or strapdown, systems. It's also called a rate sensor. Question 58: the ISA temperature at 40,000 feet is -56.5°C. Set that against the Mach number index in the airspeed window, then against a TAS of 450 knots on the outer scale, read the Mach number on the inner—0.783. Question 61: in an EFIS system, wind information can be displayed in every mode except PLAN. And question 64 gives the deflection scales: in NAV mode, 1 dot equals 2 nautical miles; in VOR mode, 1 dot equals 5 degrees; in ILS mode, 1 dot equals 1 degree. These are the book's practice questions—let's try them one at a time.