12 free practice questions from the 330 in this chapter of StudyWren Aviation. Pick an answer and check it to see the explanation and its FAA source. Part of the free Private Pilot practice test.
Density AltitudePAR-10-022
At an airport with a pressure altitude of 2,000 ft, what outside air temperature would produce a density altitude of 5,000 ft (use DA ≈ PA + 120 × (OAT − ISA))?
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The answer is C: 36°C
Required increase = 5,000 − 2,000 = 3,000 ft; 3,000 ÷ 120 = 25°C above standard. ISA at 2,000 ft = 15 − 4 = 11°C, so OAT = 11 + 25 = 36°C. The 25°C figure is only the deviation, and 11°C is the standard temperature itself, which would give a density altitude equal to pressure altitude.
Required increase = 5,000 − 2,000 = 3,000 ft; 3,000 ÷ 120 = 25°C above standard. ISA at 2,000 ft = 15 − 4 = 11°C, so OAT = 11 + 25 = 36°C. The 25°C figure is only the deviation, and 11°C is the standard temperature itself, which would give a density altitude equal to pressure altitude.
Why does takeoff distance increase at a high density altitude?
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The answer is A: The airplane must reach a higher true airspeed with less power available
Liftoff occurs at the same indicated airspeed, which corresponds to a higher true airspeed in thin air. At the same time a normally aspirated engine and the propeller produce less thrust, so acceleration is slower and the higher speed takes more runway to reach.
The answer is A: The airplane must reach a higher true airspeed with less power available
Liftoff occurs at the same indicated airspeed, which corresponds to a higher true airspeed in thin air. At the same time a normally aspirated engine and the propeller produce less thrust, so acceleration is slower and the higher speed takes more runway to reach.
Short-field takeoff, 2,400 lb, flaps 10°, paved level dry runway, zero wind (ground roll / total distance to clear a 50-ft obstacle, ft):
Pressure alt | 0°C | 10°C | 20°C | 30°C
Sea level | 820 / 1,450 | 885 / 1,560 | 955 / 1,675 | 1,025 / 1,795
Additional note: Increase the ground roll 7% for each 1% of uphill runway gradient. Pressure altitude is sea level, the OAT is 20°C, the wind is calm, and the runway has a 2% uphill gradient. What is the ground roll, to the nearest 10 ft?
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The answer is B: 1,090 ft
The chart ground roll at sea level and 20°C is 955 ft. A 2% uphill gradient × 7% per 1% = a 14% increase: 955 × 1.14 = 1,088.7 ≈ 1,090 ft. Adding only 7% treats it as a 1% gradient (1,020 ft), and taking 14% off (820 ft) treats the upslope as a benefit.
The chart ground roll at sea level and 20°C is 955 ft. A 2% uphill gradient × 7% per 1% = a 14% increase: 955 × 1.14 = 1,088.7 ≈ 1,090 ft. Adding only 7% treats it as a 1% gradient (1,020 ft), and taking 14% off (820 ft) treats the upslope as a benefit.
Short-field landing, 2,550 lb, flaps 30°, paved level dry runway, zero wind (ground roll / total distance over a 50-ft obstacle, ft):
Pressure alt | 10°C | 20°C
2,000 ft | 605 / 1,385 | 630 / 1,420
4,000 ft | 655 / 1,460 | 675 / 1,495
Notes: Decrease distances 10% for each 9 kt of headwind. For tailwinds up to 10 kt, increase distances 10% for each 2 kt. On a dry grass runway, increase the ground roll 45%.
Pressure altitude is 4,000 ft, the OAT is 10°C, the wind is calm, and the runway is dry grass. What is the landing ground roll, to the nearest 10 ft?
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The answer is A: 950 ft
Read the ground roll (the first figure) for 4,000 ft at 10°C: 655 ft on pavement. Dry grass adds 45% to the ground roll: 655 × 1.45 = 949.75 ≈ 950 ft. 2,120 ft applies the 45% to the total distance over 50 ft instead, and 655 ft leaves out the grass correction.
Read the ground roll (the first figure) for 4,000 ft at 10°C: 655 ft on pavement. Dry grass adds 45% to the ground roll: 655 × 1.45 = 949.75 ≈ 950 ft. 2,120 ft applies the 45% to the total distance over 50 ft instead, and 655 ft leaves out the grass correction.
To remain airborne for the longest time (maximum endurance) in a piston airplane, the pilot should fly at
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The answer is B: the airspeed that requires the least power
Fuel flow in a piston airplane is roughly proportional to power, so maximum endurance occurs at the airspeed for minimum power required. Maximum range in a propeller airplane occurs at the higher L/D max speed.
The answer is B: the airspeed that requires the least power
Fuel flow in a piston airplane is roughly proportional to power, so maximum endurance occurs at the airspeed for minimum power required. Maximum range in a propeller airplane occurs at the higher L/D max speed.
Which wind report gives the wind direction relative to magnetic north?
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The answer is A: The wind given by the tower or the ATIS
Winds in printed or written reports and forecasts, such as the METAR and TAF, are referenced to true north. Winds spoken by the tower or broadcast on ATIS are magnetic, so they match the runway numbers.
The answer is A: The wind given by the tower or the ATIS
Winds in printed or written reports and forecasts, such as the METAR and TAF, are referenced to true north. Winds spoken by the tower or broadcast on ATIS are magnetic, so they match the runway numbers.
The difference between standard empty weight and basic empty weight is the weight of
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The answer is A: installed optional and special equipment
Basic empty weight = standard empty weight + optional and special equipment installed. Standard empty weight already includes unusable fuel and full engine oil.
The answer is A: installed optional and special equipment
Basic empty weight = standard empty weight + optional and special equipment installed. Standard empty weight already includes unusable fuel and full engine oil.
Airplane data: Basic empty weight 1,680 lb, moment 65,520 lb-in (arm 39.0 in). Station arms (in aft of datum): front seats 37.0; rear seats 73.0; fuel 48.0 (53 gal usable, 6 lb/gal); baggage area A 95.0 (max 100 lb); baggage area B 123.0 (max 50 lb). Maximum takeoff weight 2,550 lb. CG limits: forward 35.0 in at 1,950 lb or less, increasing linearly to 41.0 in at 2,550 lb; aft 47.3 in at all weights.
Loading: pilot 190 lb (front), 20 gal of fuel, 100 lb in baggage area A, 50 lb in baggage area B (2,140 lb, moment 93,960 lb-in). What is the maximum total rear-seat passenger weight that keeps both weight and CG within limits?
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The answer is B: About 280 lb
By weight: 2,550 − 2,140 = 410 lb. By aft CG: (93,960 + 73x) ÷ (2,140 + x) = 47.3 → 25.7x = 7,262 → x ≈ 282 lb. The CG limit governs, so about 280 lb. 250 lb results from dividing by (73 − old CG) instead of (73 − 47.3).
An airplane weighs 2,300 lb. A 180-lb rear-seat passenger (arm 73.0 in) moves to the empty front passenger seat (arm 37.0 in). How far does the CG move?
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The answer is B: 2.8 in forward
ΔCG = (180 × 36.0) ÷ 2,300 = 2.8 in. The weight moved forward, so the CG moves forward. 5.7 in uses the rear-seat arm (73.0 in) instead of the 36.0-in distance moved.
ΔCG = (180 × 36.0) ÷ 2,300 = 2.8 in. The weight moved forward, so the CG moves forward. 5.7 in uses the rear-seat arm (73.0 in) instead of the 36.0-in distance moved.
What is the most hazardous effect of loading an airplane with the CG aft of the aft limit?
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The answer is A: Reduced stability and possible inability to recover from a stall or spin
An aft CG reduces longitudinal stability and leaves less nose-down elevator authority. If the CG is too far aft, the pilot may be unable to lower the nose for stall recovery, and spins may become flat and unrecoverable.
The answer is A: Reduced stability and possible inability to recover from a stall or spin
An aft CG reduces longitudinal stability and leaves less nose-down elevator authority. If the CG is too far aft, the pilot may be unable to lower the nose for stall recovery, and spins may become flat and unrecoverable.
Why should a pilot add a safety margin to POH performance figures?
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The answer is B: The data came from a new airplane flown by test pilots in ideal conditions
Manufacturers obtain performance data from flight tests of new airplanes with new engines, flown by experienced test pilots under carefully controlled conditions. A typical airplane and pilot may not achieve those numbers, so a margin should be added.
The answer is B: The data came from a new airplane flown by test pilots in ideal conditions
Manufacturers obtain performance data from flight tests of new airplanes with new engines, flown by experienced test pilots under carefully controlled conditions. A typical airplane and pilot may not achieve those numbers, so a margin should be added.
