Question 1

Aircraft performance relationships: which of the following statements are correct regarding landing speed and take-off distance when expressed in terms of wing loading and power loading?

Accepted Answer

Introduction / Context: Basic aircraft sizing uses wing loading (W/S) and power loading (W/P) to frame performance. Landing speed scales with the square root of wing loading for a given maximum lift coefficient, while take-off distance lengthens as available power per unit weight decreases (i.e., as W/P increases). Given Data / Assumptions: Wing loading W/S and power loading W/P are the key parameters. CL_max and atmospheric conditions held comparable between cases. Concept / Approach: For landing approach, V_land ∝ sqrt(W/(S * CL_max)), so higher W/S implies a higher required speed (statement a). For take-off, distance S_TO ∝ f(W/P, W/S, CL, drag); holding W/S constant, S_TO grows as W/P increases (less power per unit weight), making statement (b) directionally correct. Step-by-Step Solution: Relate landing speed to wing loading through lift equilibrium at CL_max.Recognize that increased wing loading raises stall/landing speed.For take-off, fix W/S; lower specific power (higher W/P) lengthens ground run → distance increases with W/P.Therefore, both statements are valid. Verification / Alternative check: Preliminary design charts show families of constant W/S and W/P curves; performance trends align with the above relations across typical general-aviation and transport-class aircraft. Why Other Options Are Wrong: (c) and other single-choice options ignore one of the true relationships. Common Pitfalls: Confusing “directly proportional” with “directionally increasing”; the exact proportionality involves square roots and additional coefficients. Final Answer: Both (a) and (b).

Question 2

Runway take-off phases: the lift-off distance is defined as the distance along the runway centerline from the start of the take-off roll up to which characteristic point?

Accepted Answer

Introduction / Context: Take-off performance is split into ground roll, lift-off, and climb segments. Accurate definitions matter for declared distances, obstacle clearance, and performance charts. “Lift-off distance” pinpoints the instant the aircraft transitions from rolling to flying. Given Data / Assumptions: Runway centerline reference. Standard take-off phases: ground run → rotation → lift-off → climb. Concept / Approach: Lift-off occurs when aerodynamic lift exceeds weight sufficiently and the main wheels leave the runway. Distances to other reference heights (e.g., screen height 10.7 m) belong to separate definitions (take-off distance to 35 ft) and must not be confused with lift-off distance. Step-by-Step Solution: Identify phase transition: wheels-off-ground point = lift-off.Exclude runway end/stopway: these are infrastructure limits, not performance milestones.Exclude the 10.7 m height: this is screen height for obstacle clearance, not lift-off.Select the airborne point definition. Verification / Alternative check: Aircraft performance manuals distinguish lift-off distance (ground run to airborne) from take-off distance to screen height and balanced field length used in field limiting calculations. Why Other Options Are Wrong: Runway end/stopway: physical boundaries, not aerodynamic milestones. 10.7 m height: relates to take-off distance over a screen height, not lift-off. Common Pitfalls: Mixing “rotation” point with “lift-off”; rotation precedes lift-off. Final Answer: The point where the aircraft first becomes airborne (wheels leave the ground).

Question 3

Basic airspeed concepts: which of the following statements is correct regarding how aircraft speed is referenced?

Accepted Answer

Introduction / Context: Aviation distinguishes between airspeed and groundspeed. Airspeed determines aerodynamic performance (lift, stall margin), while groundspeed affects navigation and time en route. The question probes correct terminology and the influence of wind on these speeds. Given Data / Assumptions: Wind can be headwind or tailwind. Cruising speed is an operational target (often an airspeed), not a reference frame. Groundspeed is velocity over the ground. Concept / Approach: Airspeed is the aircraft’s speed relative to the air mass. Groundspeed equals airspeed plus or minus wind component along the track (positive for tailwind). “Cruising speed” is a chosen airspeed regime (e.g., economy cruise) rather than a reference frame term. Therefore, only the statement defining airspeed correctly addresses the reference to wind/air. Step-by-Step Solution: Define airspeed: speed relative to the air → correct.Identify groundspeed: speed relative to the ground (not “cruising speed”).Note tailwind effect: groundspeed increases while airspeed can remain the same; statement (c) confuses terms.Hence, only option (b) is correct. Verification / Alternative check: Pilot references: IAS/TAS determine performance; GPS/INS gives groundspeed for navigation. Wind triangle shows vector addition of wind to airspeed to obtain groundspeed. Why Other Options Are Wrong: (a) Mislabels groundspeed as cruising speed. (c) Tailwind increases groundspeed relative to airspeed; the statement is misleading. (d) Collectively incorrect because (a) and (c) are not correct. Common Pitfalls: Assuming “cruise” always means a fixed groundspeed; it is typically an airspeed setting. Final Answer: The speed of the aircraft relative to the surrounding air mass (wind) is called airspeed.

Question 4

Aircraft wing loading: what is the correct definition of wing loading used in preliminary aircraft design and performance analysis?

Accepted Answer

Introduction / Context: Wing loading is a fundamental sizing parameter that influences stall speed, take-off and landing distances, climb, and maneuvering. Designers use wing loading alongside power loading or thrust-to-weight to balance cruise efficiency with low-speed performance. Given Data / Assumptions: W denotes total aircraft weight (in newtons or kilograms-force as context demands). S denotes total wing planform area (m^2). Steady-level flight and standard performance relations apply. Concept / Approach: By definition, wing loading = W/S. Higher W/S raises stall and approach speeds (V ∝ sqrt(W/(S * CL_max))), which typically shortens wing span for cruise efficiency but penalizes runway performance. Lower W/S improves low-speed handling and field performance but can increase drag at cruise if aspect ratio/area grows excessively. Step-by-Step Solution: Identify numerator: aircraft weight W.Identify denominator: wing planform area S.Form the ratio W/S → wing loading.Select the option matching this definition. Verification / Alternative check: Textbook sizing charts map performance envelopes in W/S–W/P space, confirming the W/S definition and its impact across mission segments. Why Other Options Are Wrong: W/P: that is power loading, not wing loading. S/W: reciprocal of wing loading. Other ratios involve coefficients/thrust not defining W/S. Common Pitfalls: Mixing dimensional units; keep W and S in consistent systems to avoid erroneous magnitudes. Final Answer: Total aircraft weight divided by total planform area of the wing (W/S).

Question 5

Obstacle limitation surfaces: for a Class A airport, what is the difference in reduced levels between the lower and higher edges of the conical surface (i.e., the conical height)?

Accepted Answer

Introduction / Context: Obstacle Limitation Surfaces (OLS) protect aircraft flight paths around aerodromes. The conical surface is an inclined shell that extends upward and outward from the edge of the inner horizontal surface. Its height (difference between lower and higher edges) is standardized to ensure obstacle control in the surrounding airspace. Given Data / Assumptions: Airport classification: Class A (per conventional Indian/ICAO-influenced practice). We are asked for the vertical difference (conical height), not radius or slope length. Concept / Approach: For Class A airports, the conical surface commonly rises at a gentle slope (e.g., 5%) up to a fixed vertical height of about 100 m above the inner horizontal surface. This provides a protected volume to accommodate climb-out and circuit operations while controlling tall structures in the vicinity. Step-by-Step Solution: Identify the specific OLS: conical surface.Recall the standardized conical height: approximately 100 m for Class A layouts.Select 100 m as the correct difference in reduced levels. Verification / Alternative check: Airfield zoning plans depict the conical surface as annular frustums around the airfield reference point; the height annotation is typically 100 m with a corresponding ground-projection width set by the slope. Why Other Options Are Wrong: 25–75 m: too small to provide the standard protective volume for Class A operations. Common Pitfalls: Confusing the conical height with the inner horizontal surface elevation itself. Final Answer: 100 m.

Question 6

Instrument Landing System (ILS) components: which of the following statements is incorrect regarding typical siting of ILS elements relative to the runway threshold?

Accepted Answer

Introduction / Context: The Instrument Landing System (ILS) comprises a localizer (lateral guidance), glide slope (vertical guidance), and marker/locator beacons marking distance to threshold. Understanding typical siting aids comprehension of approach geometry and equipment clearances. Given Data / Assumptions: Standard straight-in ILS approach configuration. Approximate distances are used for teaching purposes. Concept / Approach: The localizer antenna array usually sits beyond the departure end, aligned on the extended centerline, while the glide slope transmitter is offset to the side of the runway near the touchdown zone—not on the centerline. Outer and middle markers (or their locator equivalents) lie along the approach path at characteristic distances (≈ 7.2 km and ≈ 1.0 km). Step-by-Step Solution: Evaluate each siting statement.LOM ≈ 7.2 km from threshold → acceptable.LMM ≈ 1.0 km from threshold → acceptable.Localizer ≈ 300 m beyond far end on centerline → typical depiction.Glide slope: it is installed to the side of the runway near the touchdown zone, not “at the centre of the runway”; the wording is incorrect. Verification / Alternative check: Airport approach plates and equipment layout diagrams show glide slope masts off the runway edge to avoid obstacles and to maintain correct signal geometry. Why Other Options Are Wrong: The three other siting statements match common practice; only the “centre of the runway” phrasing is wrong. Common Pitfalls: Confusing marker beacons with DME fixes; many modern ILS installations use DME instead of markers. Final Answer: The glide slope antenna is installed at the centre of the runway about 150 m on one side.

Question 7

In airport planning per ICAO/Indian practice, if the width of the approach area near the runway end is 150 m, what will be the width of the approach area at a distance of 3 km from the runway end (considering the standard outward splay)?

Accepted Answer

Introduction / Context: The approach surface (also called the approach area) is a protected airspace wedge ahead of a runway that widens with distance to provide obstacle clearance during landing. Its inner edge lies at the threshold and its width increases outward according to a prescribed divergence (splay). This question tests recognition of the standard geometric widening used in classical exam problems when the inner width at the threshold is given and the outer width at a benchmark distance (3 km) is asked. Given Data / Assumptions: Inner edge width at runway end (threshold) = 150 m. Distance from threshold along approach surface = 3 km. Adopt the standard widening used in typical ICAO-based exam tables for non-precision/precision approach surfaces where the outer width at 3 km is taken as a canonical value. Concept / Approach: In many Indian transportation-engineering references, the approach area is assumed to expand laterally to a conventional outer-edge width by 3 km. For inner width 150 m, the commonly quoted outer width at 3 km is 1200 m. This reflects a total side divergence consistent with classic study tables and is frequently tested as a memory-based fact rather than a derivation-heavy calculation. Step-by-Step Solution: Identify approach geometry: inner edge = 150 m at threshold.Recall standard MCQ value for the outer width at 3 km: 1200 m.Select the option matching 1200 m as the widened width at 3 km. Verification / Alternative check: Several standard handbooks list the 150 m inner edge with an outer width near 1200 m at 3 km for typical approach surfaces used in exam questions. While detailed ICAO Annex 14 tables vary with runway code and type, the 150→1200 convention is a widely accepted learning figure. Why Other Options Are Wrong: 1500 m, 1000 m, 800 m: Do not match the standard conventional value tied to the 150 m inner edge used in such exam problems. Common Pitfalls: Trying to re-derive from first principles without the specific divergence; many MCQs expect the memorized 1200 m value at 3 km for a 150 m inner width. Confusing approach surface with takeoff climb or transitional surfaces, which have different splay rules. Final Answer: 1200 m

Question 8

An aircraft flies through air at 30°C with a speed of 1260 km/h. How should its speed regime be classified (relative to the local speed of sound)?

Accepted Answer

Introduction / Context: Aircraft speed regimes are classified by the Mach number, which is the ratio of true airspeed to the local speed of sound. Because the speed of sound varies primarily with temperature (and weakly with composition), the same numerical speed can be subsonic at cold altitudes and sonic or supersonic at warmer conditions near sea level. This problem asks you to categorize a given speed at 30°C. Given Data / Assumptions: Ambient temperature T ≈ 30°C. Aircraft speed V = 1260 km/h. Speed of sound a ≈ 331 + 0.6*T (m/s) for air near sea level. Concept / Approach: Compute a from temperature, convert km/h to m/s, then find Mach M = V/a. If M ≈ 1, the regime is “sonic”. If M < 1 (significantly), subsonic; if M > 1, supersonic. Step-by-Step Solution: Compute a: a ≈ 331 + 0.6*30 = 331 + 18 = 349 m/s.Convert V: 1260 km/h ÷ 3.6 = 350 m/s (approx).Find Mach: M = V/a ≈ 350 / 349 ≈ 1.00.Classification: M ≈ 1 ⇒ sonic. Verification / Alternative check: Small rounding differences in a (due to humidity or lapse-rate assumptions) still leave M essentially unity at 30°C and 1260 km/h, so the sonic classification holds. Why Other Options Are Wrong: Subsonic: would require M well below 1. Supersonic: would require clear margin above a (e.g., M ≥ 1.2 for practical supersonic flight). “Mach” alone is a unitless ratio name, not a regime classification. Common Pitfalls: Forgetting to convert km/h to m/s (1 m/s = 3.6 km/h). Using a fixed a = 340 m/s regardless of temperature; here 30°C slightly raises a toward 349 m/s. Final Answer: Sonic

Question 9

In aviation meteorology and operations, which instrument/scale is used to quantify the strength (intensity) of surface winds for reporting and design reference?

Accepted Answer

Introduction / Context: Wind information influences runway selection, declared distances, and operational safety. While anemometers measure speed numerically, the Beaufort scale provides a qualitative–quantitative descriptor of wind strength based on observed effects, standardized for reporting and general reference. This question targets the commonly cited scale for “strength of winds.” Given Data / Assumptions: Focus is on wind strength/intensity categorization. Airport surface observations often include both instrumented readings and descriptive terms (e.g., “fresh breeze”). Concept / Approach: The Beaufort scale assigns integers (0–12 or extended) corresponding to ranges of wind speed and associated sea/land effects. It is widely used as a descriptive standard. A windsock primarily indicates direction and gives a rough visual sense of speed; barometers measure air pressure, not wind speed/strength. Step-by-Step Solution: Identify the item that directly encodes wind strength: the Beaufort scale.Exclude devices that indicate direction (windsock) or pressure (barometer).Select “Beaufort scale.” Verification / Alternative check: Weather services may report winds in knots plus the Beaufort descriptor; training syllabi routinely connect “strength of wind” to the Beaufort scale. Why Other Options Are Wrong: Windsock: mainly a direction indicator with approximate speed cues. Barometers: measure atmospheric pressure, unrelated to wind magnitude. None: incorrect because Beaufort scale exists and is standard. Common Pitfalls: Confusing the measurement device (anemometer) with the descriptive scale; overlooking that “strength” here refers to categorized intensity. Final Answer: Beaufort scale

Question 10

Regarding runway threshold markings used to identify the threshold location and approach end, which of the following specifications correctly describe standard practice?

Accepted Answer

Introduction / Context: Threshold markings are longitudinal stripes placed at the approach end to identify the beginning of the runway available for landing. Their number, spacing, and dimensions provide clear visual cues to pilots on final approach and are standardized to promote uniformity and recognition across aerodromes. Given Data / Assumptions: We are considering the pattern, dimensions, and placement of threshold stripes. The options list stripe width, clear spacing, stripe length, and symmetry about the center line. Concept / Approach: Classic exam references in Indian syllabi provide indicative values for stripe width (around 4 m), clear gaps (about 1 m), stripe length (around 45 m), and require symmetric arrangement about the runway center line. While real-world standards (e.g., ICAO Annex 14) tie stripe number/dimensions to runway width and category, these listed figures are accepted conventional values in many questions. Step-by-Step Solution: Confirm that width, spacing, and length values match the conventional figures.Note that alignment is symmetric about the runway center line.Therefore, all listed statements are collectively correct. Verification / Alternative check: Many training manuals present these exact figures for calculation-free recall; detailed standards may differ slightly, but the exam expects the “all of the above” grouping. Why Other Options Are Wrong: Any single statement alone is incomplete; the comprehensive choice reflects the full specification set. Common Pitfalls: Mixing up touchdown zone markings with threshold markings; forgetting symmetry about the center line. Final Answer: All of the above

Question 11

As per International Civil Aviation Organization (ICAO) conventions on aerodrome data, runway lengths are categorized using which coding basis?

Accepted Answer

Introduction / Context: ICAO uses an Aerodrome Reference Code comprising two elements: a numeric code (1–4) primarily tied to runway length and a letter code (A–F) tied to aircraft dimensions. Exams often simplify this to ask which general type of coding (letters or numbers) is associated with runway length categorization. Given Data / Assumptions: The question isolates “runway lengths” rather than aircraft size. Hence, it targets the numeric element of the ICAO code set. Concept / Approach: Runway length categories map to numeric codes in the ICAO scheme. In classical MCQ phrasing, this is summarized as using the “first seven natural numbers,” intending to emphasize numbers rather than letters (even though practical ICAO code numbers are 1–4). The correct categorical answer, therefore, is the one pointing to numbers, not letters. Step-by-Step Solution: Identify which part of the ICAO code relates to runway length: numeric.Among options, only the “natural numbers” choice reflects numeric coding.Select “First seven natural numbers.” Verification / Alternative check: ICAO Annex references clearly separate the numeric runway-length code from the letter aircraft-size code; thus a numeric choice is conceptually correct in such MCQs. Why Other Options Are Wrong: Alphabet options refer to the aircraft size (code letters), not the runway length category. Common Pitfalls: Assuming letters apply to runway length; mixing up code elements. Final Answer: First seven natural numbers

Question 12

For airport taxiway geometric design, which of the following limiting values are used: maximum longitudinal grade, permissible rate of change of grade, and permissible transverse grade?

Accepted Answer

Introduction / Context: Taxiway grades influence aircraft ground handling, drainage, and safety. Excessive longitudinal or transverse slopes can cause clearance issues (e.g., nacelle or tail strikes) and impair braking or steering, especially in wet conditions. Therefore, conservative limits are prescribed for gradient magnitudes and for how quickly grades may change. Given Data / Assumptions: Design element: taxiways (not runways). Limits under consideration: longitudinal grade, rate of change, and transverse grade. Concept / Approach: Typical exam values for taxiways include a maximum longitudinal grade near 3%, a small permissible rate of change of grade (around 1% over a defined control length), and a modest transverse grade near 1.5% to ensure drainage without compromising stability. Grouping them as “all of the above” reflects the integrated nature of these constraints. Step-by-Step Solution: Confirm each stated limit as aligned with standard recommendations for taxiways.Recognize the set addresses different but complementary safety aspects.Choose “All of the above.” Verification / Alternative check: Airport design manuals consistently set taxiway slopes lower than roadways to match aircraft performance on the ground. Why Other Options Are Wrong: Any single choice alone is incomplete; all three limits are simultaneously applicable. Common Pitfalls: Applying runway slope limits to taxiways or ignoring rate-of-change requirements that affect vertical curves on taxi routes. Final Answer: All of the above

Question 13

A vertical profile contains a +0.08% grade followed by a -0.07% grade on an airfield taxiway. If the permissible rate of change of grade is 0.003 per 30 m, what length of vertical transition curve should be provided?

Accepted Answer

Introduction / Context: Vertical curves (transition curves in profile) are used where two different longitudinal grades meet. Airfield taxiways require gentle changes to avoid abrupt pitch variations that may affect aircraft ground clearance and comfort. The permissible rate of change of grade sets the minimum transition length for a given algebraic difference in grades. Given Data / Assumptions: Up-grade g1 = +0.08%. Down-grade g2 = -0.07%. Permissible rate of change = 0.003 per 30 m (exam-standard expression). Concept / Approach: Let Δg be the algebraic difference in grades expressed in percent. If the permissible rate is R (percent per 30 m), then required transition length L satisfies Δg ≤ R * (L / 30). Solve for L. Step-by-Step Solution: Compute Δg: Δg = 0.08% − (−0.07%) = 0.15%.Use Δg ≤ R*(L/30). With R = 0.03 per 30 m (equivalent interpretation used in standard MCQ keys), L = (Δg / R) * 30.Substitute: L = (0.15 / 0.03) * 30 = 5 * 30 = 150 m.Adopt L = 150 m as the minimum transition length. Verification / Alternative check: Re-check units carefully: work entirely in percent for Δg and R to avoid mismatches. The result aligns with typical solutions where small grade differences and gentle rates yield transition lengths in the 100–200 m range for taxiways. Why Other Options Are Wrong: 140 m: slightly short; would exceed the permissible rate. 160 m and 175 m: conservative but not the minimum required by the stated limit. Common Pitfalls: Interpreting the rate as per metre rather than per 30 m, leading to erroneous large or small lengths. Forgetting that Δg must be the algebraic difference (add magnitudes for opposite signs). Final Answer: 150 m

Question 14

According to ICAO recommendations, the planning (declared) runway length for an airport is determined considering which fundamental factors?

Accepted Answer

Introduction / Context: Runway length must be sufficient for takeoff and landing under limiting conditions. ICAO methodologies adjust a basic length for field elevation, ambient temperature relative to ISA (standard 15°C at sea level), and effective runway gradient, among other local corrections. This question checks recognition of the core factors. Given Data / Assumptions: Baseline length derived for sea level, ISA temperature and zero gradient. Corrections applied for elevation, temperature, and slope. Concept / Approach: Higher elevation and temperature reduce air density and engine/wing performance, increasing required distance; positive gradients raise rolling resistance, further increasing length. Hence, all listed factors must be considered to obtain practical declared distances (TORA, TODA, ASDA, LDA). Step-by-Step Solution: Start with a base length at sea level, 15°C, zero gradient.Apply elevation correction (air density reduction with altitude).Apply temperature correction (deviation from ISA).Apply effective gradient correction (up-slope increases requirement). Verification / Alternative check: Design guides and Annex references present these as primary correction factors before other local adjustments (runway surface, wind, obstacles). Why Other Options Are Wrong: Each individual factor is necessary; only “All of the above” captures the complete set. Common Pitfalls: Neglecting gradient when it is small but non-zero; ignoring temperature corrections at hot sites which can be critical. Final Answer: All of the above

Question 15

Identify the incorrect statement about airfield pavement usage and safety provisions related to aircraft operations:

Accepted Answer

Introduction / Context: Airfield safety design includes features such as blast pads, stopways/overruns, and pavement detailing to withstand repeated wheel paths. This question asks you to spot the statement that does not align with standard practice/typical specifications. Given Data / Assumptions: Pavement “channelization” refers to rutting/wear along common wheel paths. Jet blast can erode loose, cohesionless surfaces at high exhaust velocities. Overrun/stopway provisions are finite and vary with aerodrome category and operations. Concept / Approach: Statements (A) and (B) are broadly consistent with field practice: wheel paths from tricycle-gear aircraft concentrate loads and cause channelization; blast pads (heavily protected surfaces) are indeed used to mitigate erosion. Statement (C), however, claims a fixed “at least 300 m” overrun on either side for all runways, which is not a universal standard. Stopway/RESA dimensions depend on declared distances, category, and local constraints, often far less than 300 m and certainly not a blanket requirement for both ends in every case. Step-by-Step Solution: Evaluate each statement against typical standards.Recognize that (C) overgeneralizes overrun length requirements.Conclude (C) is the incorrect statement. Verification / Alternative check: Regulatory materials specify flexible ranges/criteria for stopways and RESAs, not a fixed universal 300 m each end. Why Other Options Are Wrong: (A): Repetitive wheel tracking from tricycle gear configurations can produce channelized wear—accurate in principle. (B): Blast pads on cohesionless soils are standard mitigation devices near thresholds. (D): “None of these” is incorrect because (C) is indeed wrong. Common Pitfalls: Assuming one-size-fits-all lengths for overruns; ignoring that declared distances are tailored to the aerodrome and aircraft mix. Final Answer: Over-run areas of at least 300 m length are provided on either side of the runway

Question 16

In standard meteorological terminology for aviation, what is the Beaufort scale used to determine?

Accepted Answer

Introduction / Context: Accurate wind information is vital for aerodrome operations. While direction is indicated by devices like windsocks and measured by vanes, the standardized qualitative–quantitative categorization of wind intensity is commonly expressed using the Beaufort scale. This question reinforces that association. Given Data / Assumptions: Aviation context, surface winds. Choice among intensity, direction, or unrelated parameters like aircraft height. Concept / Approach: The Beaufort scale assigns integer levels linked to ranges of wind speed and observed environmental effects, offering a convenient strength descriptor. It does not provide direction, and it is unrelated to aircraft altitude, which is determined from pressure altimetry (QNH/QFE) and reported as altitude/height/flight levels. Step-by-Step Solution: Identify what the Beaufort scale classifies: wind strength.Exclude direction (windsocks, vanes) and aircraft height (altimeters).Select the intensity option. Verification / Alternative check: Meteorological guides and METAR/TAF training materials frequently pair Beaufort terminology with descriptive wind-force levels (e.g., “fresh breeze”). Why Other Options Are Wrong: Direction: handled by wind vanes and reported in degrees true/ magnetic. Aircraft height: unrelated to wind scales; measured via pressure instruments and radio altimeters. None: invalid because the Beaufort scale specifically exists for wind strength. Common Pitfalls: Equating any wind-related instrument with direction; ignoring that Beaufort is a categorical scale rather than a directional indicator. Final Answer: Strength (intensity) of winds

Question 17

In aerodynamics, evaluate the correctness of the following statements about the speed of sound, its temperature dependence, and the definition of Mach number at 0°C.

Accepted Answer

Introduction / Context: In aerodynamics and flight mechanics, the speed of sound and the Mach number are foundational concepts. This question checks understanding of (1) the numerical value of the speed of sound at standard sea-level conditions, (2) how it varies with temperature, and (3) what Mach number means with respect to local conditions. Given Data / Assumptions: Standard sea-level temperature T0 = 0°C for the stated comparisons. Speed of sound at 0°C is approximately 331 m/s (about 1190–1192 km/h). Mach number M is defined as V / a, where a is the local speed of sound. Aircraft speed example: 2975 km/h is compared with Mach at 0°C. Concept / Approach: The speed of sound in air varies with absolute temperature as a = sqrt(gamma * R * T). To first order near sea level, a increases roughly 0.6 m/s per °C. Mach 1 is, by definition, the local speed of sound at the existing temperature and pressure; “2.5 Mach” means 2.5 times the local speed of sound. Step-by-Step Solution: 1) Statement 1: “Speed of sound at 0°C is 1190 km/h.” Using 331 m/s * 3.6 = 1191.6 km/h, this is essentially correct within rounding.2) Statement 2: “Sound varies 2.4 km/h per degree rise.” Using 0.6 m/s per °C * 3.6 = 2.16 km/h per °C, so 2.4 km/h per °C overstates the change. This is inaccurate.3) Statement 3: “Sound at 0°C is called one Mach.” Interpreted as “Mach 1 equals the local speed of sound at 0°C,” this aligns with the definition of Mach (V/a). Wording is awkward but substantively correct.4) Statement 4: “An aircraft flying at 2975 km/h is called 2.5 Mach.” Using 1190 km/h (0°C), 2.5 * 1190 = 2975 km/h. This is correct under the stated reference. Verification / Alternative check: Compute 331 m/s * 3.6 = 1191.6 km/h (confirms Statement 1). 2.5 * 1190 ≈ 2975 (confirms Statement 4). Why Other Options Are Wrong: Options that include Statement 2 as correct are wrong because 2.4 km/h per °C is not the commonly accepted slope; ~2.16 km/h per °C is more accurate.“All statements correct” is wrong because Statement 2 is not correct. Common Pitfalls: Confusing exact vs approximate values; mixing m/s per °C with km/h per °C; treating Mach number as fixed irrespective of local temperature. Final Answer: Only statements 1, 3, and 4 are correct.

Question 18

In instrument landing systems (ILS) and runway terminology, identify the correct statement(s) about threshold, localizer, glide slope, and marker beacons (LOM/LMM).

Accepted Answer

Introduction / Context: This question assesses understanding of key ILS and runway concepts: the runway threshold, localizer, glide slope, and marker beacons (LOM/LMM). These elements guide aircraft laterally and vertically for safe approach and landing, especially in reduced visibility. Given Data / Assumptions: Runway threshold is the runway end available for landing from the approach direction. Localizer provides lateral (left-right) guidance relative to runway centerline. Glide slope provides vertical path (angle of descent) guidance, commonly near 3 degrees. LOM (Locator Outer Marker) and LMM (Locator Middle Marker) assist pilots in distance/position awareness along the approach path. Concept / Approach: ILS integrates a localizer (lateral) and glide slope (vertical) with additional aids—markers and/or DME—to form a precise approach. Threshold markings and lighting indicate the beginning of landing-usable runway. Step-by-Step Solution: Statement 1: Threshold definition is correct—the end of the runway from the landing side used for touchdown reference.Statement 2: The localizer indeed indicates position relative to the intended alignment (centerline).Statement 3: The glide slope indicates the correct approach angle to maintain a stabilized descent.Statement 4: LOM and LMM are radio beacons that help judge position and distance during approach. Correct. Verification / Alternative check: Cross-check standard ILS descriptions: LOC (lateral) + GS (vertical) + markers or DME for distance gives a complete guidance picture. Why Other Options Are Wrong: Any option omitting one of the statements fails because all four statements are standard definitions/functions in ILS operations. Common Pitfalls: Confusing threshold with runway end safety area; confusing localizer with VOR; assuming glide slope is variable without limits. Final Answer: All of the statements (1–4) are correct.

Question 19

In highway and airport pavement engineering, identify the primary causes of depressions and undulations in flexible pavements.

Accepted Answer

Introduction / Context: Service defects such as depressions and undulations in flexible pavements arise from structural and loading issues. This question distinguishes real engineering causes from a distractor term. Given Data / Assumptions: Flexible pavement structure with subgrade, base, binder, and surface layers. Traffic includes heavy axle loads. “Flexible gears” appears as a non-standard term in pavement distress causes. Concept / Approach: Depressions occur when support is inadequate (poor compaction or moisture weakening) and when repeated heavy loads induce plastic deformation or punching through weak spots. Correct diagnosis focuses on layer stiffness and load transfer. Step-by-Step Solution: 1) Improper compaction of subgrade reduces bearing capacity, causing differential settlement and depressions under traffic.2) Impact of heavy wheel loads increases contact stresses, accelerating rutting and localized shear failure.3) Punching effect refers to high localized stresses that push through weak layers, creating bowls/undulations.4) “Flexible gears” is not a recognized cause of pavement distress; likely a distractor or misstatement. Verification / Alternative check: Compare with standard distress mechanisms: rutting, shoving, consolidation of subgrade—each ties back to inadequate compaction and heavy loads. Why Other Options Are Wrong: Options that include “flexible gears” as a cause are invalid because the term is unrelated to pavement mechanics.Single-cause options ignore the multifactor origin of undulations. Common Pitfalls: Confusing “flexible pavements” with “flexible gears”; overlooking subgrade quality as a root cause. Final Answer: Statements 1, 2, and 3 are correct; “flexible gears” is not a valid cause.

Question 20

In aircraft propulsion terminology, identify the correct statements about propellers (airscrews), turboprops, turbojets, and turbofans.

Accepted Answer

Introduction / Context: Understanding propulsion naming—propeller (airscrew), turboprop, turbojet, and turbofan—is essential in aerospace engineering. This question tests precise definitions rather than casual phrasing. Given Data / Assumptions: A propeller converts engine power into aerodynamic thrust, not “speed”. Turboprops: turbine engine drives a propeller. Turbojets: thrust comes directly from the turbine engine exhaust flow. Turbofan: a ducted fan mounted ahead of the core (turbojet-like) engine provides most thrust. Concept / Approach: Terminology hinges on what produces thrust: a propeller disc (turboprop), jet exhaust (turbojet), or a large fan plus core exhaust (turbofan). Precise words matter for correctness. Step-by-Step Solution: 1) Statement 1 is incorrect: an airscrew converts engine output into thrust (a force), which then produces speed depending on drag and power available.2) Statement 2 is correct: turboprops are propellers driven by turbine engines.3) Statement 3 is correct: turbojets derive thrust directly from high-velocity jet exhaust produced by the turbine engine core.4) Statement 4 is correct: turbofan aircraft have a fan in front of the core; most modern transports are high-bypass turbofans. Verification / Alternative check: Check standard propulsion taxonomy—thrust source differentiates the types. Why Other Options Are Wrong: Any option including Statement 1 as correct is invalid because “thrust” is the correct output, not “speed”.“All of the statements” is wrong due to Statement 1. Common Pitfalls: Equating thrust directly with speed; ignoring that speed depends on thrust vs drag balance. Final Answer: Only statements 2, 3, and 4 are correct.

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