Answer C — Page 624, Lesson 729

I want to walk you through the answers to these practice questions, because each one carries a solid piece of instrument knowledge you'll need. Let's take them in order. Question 9 gives us the formula for angle of bank in a rate one turn. The rule of thumb is: angle of bank equals true airspeed divided by 10, plus 7 degrees. So for a true airspeed of 120 knots, we take 120 divided by 10, which is 12, then add 7, giving us 19 degrees of bank. That's the standard rate one turn bank angle for that speed. Question 10 deals with rate of descent. The rule of thumb here is: rate of descent in feet per minute equals 5 times the aircraft's ground speed. So if ground speed is 100 knots, we multiply by 5 and get 500 feet per minute rate of descent. Note it's ground speed, not airspeed — that's an important distinction. Question 11 is about TCAS, the Traffic Collision Avoidance System. There are three generations. TCAS I issues only a Traffic Advisory — that's an alert to the pilot, but manoeuvre of the aircraft is prohibited. TCAS II issues a Corrective Resolution Advisory, which instructs the pilot to take corrective action in the vertical plane only. TCAS III issues a Corrective Resolution Advisory that instructs corrective action in the vertical and/or horizontal planes. Now, there's a critical distinction here. Do not confuse a Corrective Resolution Advisory with a Preventative Resolution Advisory. A Preventative one only provides limitations on aircraft manoeuvres — it tells you what you must not do. A Corrective one actually issues corrective aircraft manoeuvres — it tells you what to do. That contrast is exam gold. Question 12 is about the pitot static system. A leak in the total, or pitot, pressure line will exhaust a percentage of that pressure to atmosphere. The result is that both the Airspeed Indicator and the Machmeter will under-read. Why? Because the loss of pressure causes the airspeed capsules in both instruments to under-expand. The capsule is the sensing element, and if it doesn't get full pressure, it doesn't expand fully, so the reading is low. Question 13 is about the classic attitude indicator — that's the air driven artificial horizon. During a standard 360 degree turn, there are characteristic errors. Let me walk through the table. At roll in, at 360 degrees, pitch is normal and roll is normal. At 90 degrees into the turn, pitch reads high, nose up, and roll reads too low. At 180 degrees, pitch is still high, nose up, but roll is now normal. At 270 degrees, pitch is still high, nose up, and roll reads too high. Then at roll out, back at 360 degrees, everything returns to normal. This error is corrected by the application of compensation tilt — that's the mechanism built into the instrument to counter this precession effect. Question 14 simply refers back to the answer for question 6, so there's nothing new there. Question 15 is a neat proof you can do on the navigation computer. Set all parameters for ISA — International Standard Atmosphere — at mean sea level. Then read off CAS, calibrated airspeed, on the inner scale against TAS, true airspeed, on the outer scale. They will be the same. That makes sense because at ISA mean sea level, with no compressibility or density altitude effects, calibrated and true airspeed coincide. So the key takeaways: rate one turn bank formula, the 5 times ground speed descent rule, the TCAS generations and the corrective versus preventative distinction, the pitot leak effect on ASI and Machmeter, the classic attitude indicator error pattern with compensation tilt, and the CAS equals TAS condition at ISA sea level.