40 questions
Correct: B)
Explanation: The maximum take-off mass (MTOM) is a structural and aerodynamic certification limit. Exceeding it raises wing loading, increases the stall speed, degrades climb and glide performance, and overstresses the airframe beyond certified load factors. No pilot technique can compensate for the resulting structural and aerodynamic penalties. There is no regulatory tolerance for any excess, however small.
Correct: B)
Explanation: The approved C.G. envelope defines the range within which stability and controllability have been flight-tested and certified. A C.G. forward of the front limit may leave insufficient elevator authority for rotation or flare. A C.G. aft of the rear limit makes the aircraft statically unstable. The C.G. must remain within both limits throughout all phases of flight.
Correct: C)
Explanation: The C.G. position relative to the aerodynamic neutral point determines longitudinal static stability, while elevator authority provides controllability. If the C.G. falls outside the certified envelope, one of these two properties is compromised. Stall speed and VNE are governed by other parameters and are not the primary reasons for C.G. limits.
Correct: D)
Explanation: An aft C.G. beyond the rear limit reduces or eliminates longitudinal static stability. The aircraft may pitch up violently and uncontrollably because the restoring moment disappears. A forward C.G. is less dangerous because it merely increases stick forces and reduces performance; an aft C.G. can make the aircraft unflyable.
Correct: C)
Explanation: Each aircraft is physically weighed on calibrated scales to determine its actual empty mass and C.G. position. Manufacturing tolerances, installed equipment, and repairs cause differences between serial numbers of the same type, so manufacturer tables or other aircraft of the same type cannot be relied upon. The results are recorded in the weight and balance report and updated after any modification.
Correct: C)
Explanation: Unsecured cargo can shift suddenly in turbulence or manoeuvres, moving the C.G. outside limits faster than a pilot can react. A sudden aft shift can trigger an unrecoverable pitch-up. Loose items can become projectiles, injuring occupants or jamming controls. The structural risk from asymmetric or excessive local loading may exceed design limits.
Correct: D)
Explanation: By definition, the centre of gravity is the single point through which the resultant gravitational force (weight vector) acts on the entire aircraft. The centre of pressure is where the resultant aerodynamic force acts, the neutral point is the aerodynamic reference for stability analysis, and the stagnation point is where airflow velocity reaches zero on the leading edge.
Correct: B)
Explanation: The centre of gravity is the mass-weighted average position of all individual mass elements. It is the point through which the total weight force is considered to act. It is distinct from the neutral point (an aerodynamic stability concept), is not the heaviest single component, and has no fixed geometric relationship to the midpoint between neutral point and datum.
Correct: C)
Explanation: Moment = mass x balance arm (M = m x d), expressed in units such as kg-m or lb-in. The total C.G. position is found by dividing the sum of all moments by the total mass. Using a sum, difference, or quotient instead of a product would yield dimensionally incorrect results.
Correct: D)
Explanation: The balance arm (moment arm) is the horizontal distance measured from the aircraft's datum to the centre of gravity of a specific mass item. It determines the leverage that mass exerts about the datum. The datum itself is a fixed reference point, not the balance arm. Distances from the overall C.G. are not balance arms.
Correct: C)
Explanation: In mass and balance terminology, the balance arm is the horizontal distance from the datum to any point of interest, including the overall C.G. once calculated. Torque (or moment) is the product of mass and arm, not the distance itself. Span is a wing dimension unrelated to longitudinal mass and balance.
Correct: C)
Explanation: The datum is a fixed reference defined in the flight manual. The balance arm of any mass item is measured from this datum to the centre of gravity of that specific item. All moment calculations use the datum as a common reference so that moments can be summed algebraically to determine the total C.G. position.
Correct: D)
Explanation: The Pilot's Operating Handbook (POH) or Aircraft Flight Manual (AFM) contains a dedicated mass and balance section listing the empty mass, empty C.G., datum, C.G. limits, and approved loading configurations. The certificate of airworthiness certifies the type; annual inspection records document maintenance; the performance section covers speeds and glide data.
Correct: B)
Explanation: The Weight and Balance section (typically Section 6 in an EASA-standardised AFM) records the basic empty mass, empty C.G. location, allowable C.G. range, and loading instructions. The Limitations section covers speeds and load factors; Normal Procedures covers checklists; Performance covers climb, glide, and speed data.
Correct: C)
Explanation: Initial moment = 610 x 80.0 = 48,800. Removed moment = 10 x 150 = 1,500. New moment = 48,800 - 1,500 = 47,300. New mass = 600 kg. New C.G. = 47,300 / 600 = 78.833. Since the removed item was aft of the original C.G. (150 > 80), removing it shifts the C.G. forward, which is consistent with the result.
Correct: C)
Explanation: Moving mass x from the current C.G. (arm 80) to arm 150 shifts the C.G. aft. The new C.G. = (6400 x 80 + x x (150 - 80)) / 6400 must not exceed 80.5. Solving: x x 70 / 6400 = 0.5, so x = 6400 x 0.5 / 70 = 45.71 lbs. This is the maximum mass that can be relocated without violating the aft limit.
Correct: C)
Explanation: Safe loading demands that both the total mass stays within MTOM and the payload is distributed so the C.G. remains within limits. Exceeding either the mass limit or the C.G. envelope independently compromises safety. Checking only one condition is insufficient.
Correct: D)
Explanation: The maximum pilot seat load is a structural certification limit. Trim adjustments do not change the actual mass and do not make the aircraft compliant. Reducing water ballast does not address a cockpit overload. The only correct action is to reduce the payload (remove equipment, lighter pilot parachute, etc.) until the certified limit is respected.
Correct: C)
Explanation: When the aft C.G. limit is exceeded, the load must be redistributed so that more mass is placed forward. Trim changes do not alter the physical mass distribution and cannot solve a structural C.G. problem. Flying with the C.G. beyond the aft limit is dangerous regardless of total mass.
Correct: C)
Explanation: A motorless glider converts potential energy (height) into kinetic energy. The component of the weight vector projected along the descending flight path balances drag and maintains airspeed. Ascending air can reduce or reverse the descent but does not propel the aircraft forward. A tailwind changes groundspeed but does not generate a propulsive force along the flight path.
Correct: C)
Explanation: A headwind reduces groundspeed at touchdown while airspeed remains normal, so less kinetic energy must be dissipated during the ground roll. High density altitude and high pressure altitude increase true airspeed for a given IAS, lengthening the ground roll. Heavy rain can degrade braking effectiveness and increase landing distance.
Correct: A)
Explanation: A headwind reduces groundspeed while the sink rate remains unchanged. Since the aircraft covers less horizontal distance per unit of height lost, the descent angle relative to the ground increases (steepens). Conversely, a tailwind reduces the glide angle over the ground. The air-mass glide angle is unaffected by wind.
Correct: B)
Explanation: On sloping terrain, landing uphill shortens the ground roll because gravity assists deceleration. A slightly higher approach speed provides a safety margin against turbulence and wind shear near unfamiliar terrain. Landing downhill would drastically increase the stopping distance and is extremely dangerous.
Correct: D)
Explanation: Rain on the wing surface degrades aerodynamic characteristics by increasing surface roughness and altering the effective aerofoil profile. The stall speed may rise slightly and control effectiveness may be reduced. A higher approach speed provides the necessary safety margin. A shallower approach would reduce obstacle clearance and extend the final segment.
Correct: C)
Explanation: A waterlogged grass surface increases rolling resistance due to soft ground deformation and water drag. Rain-flattened grass adds further resistance. The take-off run is therefore longer compared with a dry grass runway. Aquaplaning is a concern on hard surfaces with standing water but does not apply in the same way to soft grass.
Correct: B)
Explanation: On landing, wet grass reduces friction between the skid or wheel and the surface, causing the glider to slide more easily and decelerate over a shorter distance than on dry grass. This is the opposite effect to take-off, where the soft ground increases resistance during acceleration.
Correct: B)
Explanation: In strong thermal conditions, the glider flies fast between thermals to optimise average cross-country speed (MacCready theory). Higher wing loading shifts the speed polar to higher speeds, improving the achievable glide ratio at those speeds. The trade-off is a higher stall speed and higher best-glide speed, which is acceptable when thermals are strong enough to compensate for the increased sink rate during climbs.
Correct: C)
Explanation: Stall speed (and thus minimum speed) is proportional to the square root of wing loading. With a 40% increase: new Vs = Vs x sqrt(1.40) = Vs x 1.183, an increase of approximately 18%. The relationship is non-linear, so doubling wing loading does not double the stall speed.
Correct: D)
Explanation: The maximum glide ratio (best L/D) is essentially independent of mass because both lift and drag scale with mass in the same proportion. What changes: the speed for best L/D increases, the sink rate at any given speed increases, wing loading increases, and the minimum speed rises. Only the achievable L/D ratio itself remains virtually constant.
Correct: D)
Explanation: Speed polar curves for different masses show that the tangent from the origin (which determines best L/D) touches each curve at the same slope. The maximum glide ratio is therefore the same regardless of mass. However, the speed at which best L/D occurs is higher for heavier configurations, and minimum speed increases with mass.
Correct: D)
Explanation: Glide distance = glide ratio x height = 30 x 1,500 m = 45,000 m = 45 km. Note that 45 NM would equal approximately 83 km, requiring a glide ratio of about 1:55. Always verify units: mixing nautical miles and metres is a common source of error.
Correct: D)
Explanation: Ground speed = distance / time = 150 km / 1.25 h = 120 km/h. Convert 1 hour 15 minutes to decimal: 15 min = 0.25 h, so total = 1.25 h. A common error is to write 1.15 instead of 1.25.
Correct: C)
Explanation: The airspeed indicator measures dynamic pressure, which depends on air density. At 6,000 m the air density is significantly lower than at sea level, so a higher true speed is needed to produce the same dynamic pressure. In practice, TAS exceeds IAS by roughly 2% per 300 m of altitude. At 6,000 m, TAS is approximately 20-25% higher than IAS.
Correct: C)
Explanation: The VNE on the ASI is set for low altitude. At high altitude, the same IAS corresponds to a much higher TAS, which can approach or exceed the structural flutter speed. Glider flight manuals provide a speed-altitude table giving the reduced IAS limit for each altitude. At 6,000 m the permissible IAS is significantly lower than the sea-level VNE marking.
Correct: B)
Explanation: Aerodynamic forces depend on dynamic pressure, which is what the airspeed indicator measures. The correct approach IAS is the same regardless of aerodrome elevation. The TAS will be higher at altitude due to lower air density, but the pilot reads and flies the same indicated speed on the ASI.
Correct: B)
Explanation: The angle of descent (glide angle) is the geometric angle between the horizontal plane and the flight path vector, measured in degrees. The glide ratio is the inverse tangent relationship: glide ratio = 1 / tan(glide angle). A glide ratio of 1:30 corresponds to a glide angle of approximately 1.9 degrees. Expressing it as a percentage would make it a gradient, not an angle.
Correct: D)
Explanation: Moist ground, water bodies, and marshes have high thermal inertia and absorb solar radiation without heating up quickly, suppressing thermal development above them. Flying over large stretches of such terrain means less lift and a higher risk of a forced landing in unsuitable terrain. Dry fields, rocky areas, and built-up surfaces generate stronger thermals.
Correct: D)
Explanation: After rounding a downwind turning point, the glider loses its tailwind advantage and faces a headwind that reduces groundspeed and shortens glide distance over the ground. Arriving high provides maximum altitude reserve for the upwind leg. Arriving low with an immediate turn into headwind leaves no margin for finding lift or selecting a landing field.
Correct: C)
Explanation: When the glider turns through 90 or 180 degrees at a waypoint, the pilot's perspective of the sky shifts dramatically. The sun appears to have moved relative to the aircraft heading, and cumulus clouds that were behind or to one side now appear ahead. This perceptual change can make the sky look completely different even though objective conditions have not changed. Pilots must re-orient their thermal assessment to the new heading.
Correct: D)
Explanation: Interception lines are prominent linear ground features -- rivers, coastlines, railways, motorways -- selected during pre-flight planning that run roughly perpendicular to the planned route. If a pilot becomes disoriented, flying towards the nearest interception line produces an unmistakable landmark for position recovery. They do not extend VFR permissions, are not range indicators, and are not airport markers.
