Performance — Single-Engine AeroplanesAir Navigation — DGCA CPL practice questions
Question 1 of 10
Density altitude is defined as:
All 10 questions — Performance — Single-Engine Aeroplanes
Air Navigation · DGCA CPL. The correct option is marked on each.
Q1. Density altitude is defined as:
- A.Altitude shown on the altimeter with 1013 set
- B.Altitude in the ISA at which air density equals actual density✓
- C.True altitude corrected for temperature
- D.Altitude above the aerodrome elevation
Why: Density altitude is the altitude in the International Standard Atmosphere (ISA) at which the air density equals the actual density. High density altitude = reduced engine and aerodynamic performance.
Q2. Which combination gives the highest density altitude?
- A.High elevation, low temperature, low humidity
- B.Low elevation, high temperature, high humidity
- C.High elevation, high temperature, high humidity✓
- D.Sea level, standard temperature, dry air
Why: Density altitude increases with elevation, high temperature, and high humidity (water vapour displaces denser air). Hot, high, humid conditions give the worst (highest) density altitude.
Q3. Vx (best angle of climb speed) gives:
- A.Maximum altitude gain per unit time
- B.Maximum altitude gain per unit distance (steepest climb angle)✓
- C.Minimum fuel burn per hour
- D.Maximum range at climb power
Why: Vx provides the greatest altitude gain per horizontal distance flown — used to clear obstacles after takeoff. Vy gives maximum altitude per unit time (best rate).
Q4. On a single-engine aircraft, increasing aircraft weight will:
- A.Reduce stall speed
- B.Have no effect on stall speed
- C.Increase stall speed✓
- D.Only affect cruise performance
Why: Stall speed increases with weight because more lift (higher speed) is needed to support the greater mass. VS ∝ √W.
Q5. Takeoff distance required will be LONGEST under which conditions?
- A.Sea level, cold temperature, dry hard runway
- B.High elevation, hot temperature, soft grass runway, uphill slope✓
- C.Sea level, cold temperature, into-wind
- D.Short grass, downslope, standard temperature
Why: TODR increases with: high altitude/density altitude, high temperature, wet/soft/grass surface, uphill slope, and tailwind. The worst case combines all factors.
Q6. The effect of a 10 kt headwind on takeoff distance is approximately:
- A.5% reduction
- B.10% reduction✓
- C.20% reduction
- D.No effect
Why: A 10 kt headwind (roughly 10% of a typical light aircraft rotation speed) reduces takeoff distance by approximately 10%. Tailwind has the opposite and more severe effect.
Q7. Best Glide Speed (Vbg) provides:
- A.Minimum sink rate
- B.Maximum distance over the ground per unit altitude lost✓
- C.Maximum time aloft after engine failure
- D.Best altitude gain in still air
Why: Vbg = best L/D ratio speed, giving maximum glide distance per unit height loss. At Vbg the aircraft travels farthest from altitude — critical for engine-failure glide to a landing area.
Q8. As altitude increases, the indicated airspeed for best range (Carson's speed / LRC) in a piston aircraft:
- A.Increases
- B.Decreases significantly
- C.Remains approximately the same indicated airspeed✓
- D.Becomes equal to Vmo
Why: For a piston aircraft, best-range IAS remains approximately constant with altitude because the aerodynamic relationship is the same — although TAS and true air range both increase with altitude.
Q9. Flap extension during takeoff generally:
- A.Increases both lift and drag equally
- B.Increases lift and reduces stall speed — allowing shorter ground roll — but increases drag, reducing climb gradient✓
- C.Reduces lift at all settings
- D.Has no significant effect below 15° deflection
Why: Partial flap on takeoff increases lift coefficient, lowering rotation speed (shorter ground roll). However, the drag penalty reduces climb gradient — so obstacle clearance may be worse despite shorter ground roll.
Q10. TORA, TODA, and ASDA are defined distances on a runway. TODA is:
- A.Same as TORA
- B.TORA + stopway
- C.TORA + clearway✓
- D.TORA + stopway + clearway
Why: TODA (Takeoff Distance Available) = TORA + any clearway. ASDA = TORA + any stopway. Clearway can only be used for the airborne phase; stopway is for rejected takeoff.