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Mauritius DCA IR Theory study materials
Mauritius DCA IR Theory study resources

Mauritius DCA IR Theory practice questions

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Question 1Air Law and ATC Procedures (instrument flight rules)

Under ICAO Annex 2, an aircraft operating under IFR in controlled airspace must maintain a listening watch on the appropriate radio frequency and, unless otherwise authorised, must also comply with which requirement?

  1. Report position only when crossing a mandatory reporting point
  2. Establish radio contact with the destination aerodrome before departure
  3. Transmit a position report every fifteen minutes regardless of radar coverage
  4. Maintain continuous two-way radio communication with the controlling ATS unit Correct answer.

Explanation

Annex 2 requires IFR flights in controlled airspace to maintain continuous two-way radio communication with the ATS unit concerned, unless special arrangements such as radar monitoring have been authorised. Position reporting may be reduced when radar identification is maintained, so a fixed reporting interval is not the general rule.

Question 2Air Law and ATC Procedures (instrument flight rules)

In Mauritius-controlled airspace, an IFR aircraft is given the clearance 'cleared to the Mauritian FIR boundary via flight planned route, maintain FL150'. What does this clearance authorise the pilot to do?

  1. Descend to FL150 only after passing the FIR boundary
  2. Select any level above FL150 provided the FIR boundary is reached on time
  3. Fly the cleared route to the FIR boundary and maintain FL150 until further advised Correct answer.
  4. Deviate from the flight-planned route to avoid weather without informing ATC

Explanation

The clearance defines the route limit (the FIR boundary) and the assigned level (FL150). The pilot may fly the cleared route and must maintain FL150 until a further clearance is issued, since an assigned level remains binding until amended.

Question 3Air Law and ATC Procedures (instrument flight rules)

What is the standard minimum vertical separation applied by ATC between IFR aircraft in the cruise above FL290 in airspace where RVSM is implemented?

  1. 900 m (3000 ft)
  2. 300 m (1000 ft) Correct answer.
  3. 150 m (500 ft)
  4. 600 m (2000 ft)

Explanation

Within designated RVSM airspace, the standard vertical separation minimum between suitably equipped aircraft is 300 m (1000 ft) up to FL410. The older 600 m (2000 ft) minimum above FL290 no longer applies in RVSM airspace.

Question 4Air Law and ATC Procedures (instrument flight rules)

An IFR flight plan is submitted for a flight departing Mauritius. Which element is mandatory in the filed flight plan for the flight to be acceptable to ATS?

  1. The pilot's total flying hours and licence number
  2. The aircraft's last maintenance check date
  3. The cruising speed, cruising level and route to be followed Correct answer.
  4. The number of cabin crew on board

Explanation

A flight plan must contain the aircraft identification, flight rules, type of aircraft, and the route including cruising speed and cruising level. Pilot licensing and maintenance data are not flight plan items.

Question 5Air Law and ATC Procedures (instrument flight rules)

When may a pilot of an IFR aircraft in controlled airspace change from IFR to VFR flight?

  1. Only after informing ATC and receiving an explicit clearance to cancel the IFR flight plan Correct answer.
  2. At any time the pilot considers the meteorological conditions suitable
  3. After broadcasting the change on the distress frequency
  4. Immediately upon leaving cloud, provided visibility exceeds 5 km

Explanation

A change from IFR to VFR requires notification to ATC and an explicit clearance, because the controller must know the aircraft is no longer subject to IFR separation. The pilot's own assessment of weather alone does not authorise the change.

Question 6Air Law and ATC Procedures (instrument flight rules)

What does the term 'estimated time of arrival' (ETA) mean for an IFR flight plan?

  1. The time the aircraft enters the destination FIR
  2. The time the aircraft leaves the departure gate
  3. The estimated time at which the aircraft will arrive over the destination aerodrome Correct answer.
  4. The time the aircraft begins its descent

Explanation

In flight plan terminology, ETA refers to the estimated time the aircraft will arrive over the point of destination, normally the destination aerodrome. It is used by ATS for planning and for alerting services.

Question 7Air Law and ATC Procedures (instrument flight rules)

An IFR aircraft is cleared to descend to 4000 ft on the ILS approach to runway 14 at Mauritius. At what point must the pilot discontinue the approach if visual reference is not established?

  1. At 1000 ft above aerodrome elevation regardless of procedure
  2. Only after the aircraft has touched down
  3. Whenever the controller instructs, since the pilot cannot decide
  4. At the decision altitude or missed approach point specified for the procedure Correct answer.

Explanation

On a precision approach, the pilot must decide to continue or go around at the decision altitude; on a non-precision approach, at the missed approach point. If the required visual reference is not established by that point, a missed approach must be executed.

Question 8Air Law and ATC Procedures (instrument flight rules)

Under ICAO rules, what is the minimum IFR cruising altitude over high terrain unless a higher minimum is specified?

  1. 3000 ft above the highest obstacle within 16 km
  2. 500 ft above the highest obstacle within 3 km
  3. 1000 ft above the highest obstacle within 5 km
  4. 2000 ft above the highest obstacle within 8 km of the estimated position Correct answer.

Explanation

The general ICAO minimum for IFR flight over high terrain is 2000 ft (600 m) above the highest obstacle within a horizontal distance of 8 km from the estimated position. Lower minimums apply over terrain below specified elevations where published.

Question 9Air Law and ATC Procedures (instrument flight rules)

A controller issues the instruction 'descend now to FL120, cross the Mauritius VOR at or above FL150'. What must the pilot do?

  1. Continue descent to FL120 but ensure the aircraft is at or above FL150 when crossing the VOR Correct answer.
  2. Descend below FL120 to ensure crossing the VOR early
  3. Descend to FL150 and remain there until the VOR
  4. Ignore the crossing restriction because it conflicts with the descent

Explanation

A crossing restriction sets a vertical limit at a designated point, and the pilot must plan the descent so that the aircraft is at or above FL150 at the VOR while still complying with the cleared level of FL120. The two constraints are compatible if the descent is managed correctly.

Question 10Air Law and ATC Procedures (instrument flight rules)

What is the purpose of a standard instrument departure (SID) route in IFR operations?

  1. To replace the need for an IFR clearance
  2. To allow pilots to choose any route they prefer after takeoff
  3. To define only the noise-abatement procedure
  4. To provide a published route from the aerodrome to a specified point for ATC separation and obstacle clearance Correct answer.

Explanation

A SID provides a published IFR route from the aerodrome to a significant point, ensuring obstacle clearance and enabling ATC to separate traffic predictably. It does not remove the need for an ATC clearance.

Question 11Air Law and ATC Procedures (instrument flight rules)

In the event of a two-way radio communication failure in IMC, what level should an IFR aircraft normally maintain after the failure?

  1. An immediate descent to the minimum safe altitude
  2. The level assigned by the destination approach controller
  3. The last assigned level, then the level in the flight plan, following the published lost-communication procedure Correct answer.
  4. A climb to the highest available level

Explanation

The standard lost-communication procedure requires the aircraft to maintain the last assigned level for a specified period, then continue at the level in the current flight plan, and to follow the published route and timing to the destination. Descents are made only in accordance with the procedure.

Question 12Air Law and ATC Procedures (instrument flight rules)

What does a 'clearance limit' in an IFR clearance represent?

  1. The maximum altitude the aircraft may fly
  2. The boundary of the radar coverage
  3. The time by which the aircraft must land
  4. The point to which the aircraft is cleared to proceed Correct answer.

Explanation

The clearance limit is the point to which an IFR aircraft is authorised to proceed, often the destination aerodrome or a specified fix. It is distinct from the assigned level and from any time restriction.

Question 13Air Law and ATC Procedures (instrument flight rules)

During an IFR flight in Mauritius airspace, ATC issues a heading to the pilot for vectoring. What does accepting the heading imply?

  1. The pilot must abandon the flight-planned route permanently
  2. The pilot is relieved of all responsibility for terrain clearance
  3. The heading overrides any published minimum altitude
  4. The pilot may fly the heading and is responsible for terrain clearance unless advised of radar terrain separation Correct answer.

Explanation

When vectored, the pilot flies the assigned heading but remains responsible for terrain clearance unless the controller has advised that radar terrain separation is being provided. A heading does not cancel minimum altitude requirements.

Question 14Air Law and ATC Procedures (instrument flight rules)

Which condition must be met for an aircraft to operate under IFR in controlled airspace without a filed flight plan?

  1. The pilot may proceed if the flight remains clear of cloud
  2. The pilot may proceed if the flight is under radar contact
  3. No such operation is permitted; an IFR flight plan must be filed and a clearance obtained Correct answer.
  4. The pilot may file after departure and proceed meanwhile

Explanation

IFR flight in controlled airspace requires a flight plan and an ATC clearance before entry. Filing after departure or relying on radar contact does not substitute for the required flight plan and clearance.

Question 15Air Law and ATC Procedures (instrument flight rules)

An IFR aircraft is at FL180 and ATC advises 'traffic, one o'clock, five miles, opposite direction, FL190'. What action is expected of the pilot?

  1. Climb immediately to FL190 to increase separation
  2. Turn right to avoid the traffic without ATC instruction
  3. Descend to FL170 without notifying ATC
  4. Maintain the assigned level and report the traffic in sight or advise negative contact Correct answer.

Explanation

Traffic information does not alter the clearance; the pilot maintains the assigned level and reports whether the traffic is in sight. Any avoiding action must be coordinated with ATC unless a collision hazard demands immediate action.

Question 16Air Law and ATC Procedures (instrument flight rules)

In which situation is a pilot of an IFR aircraft required to notify ATC immediately?

  1. When the flight is expected to arrive five minutes early
  2. When the pilot changes the destination alternate in the flight plan
  3. When the aircraft's navigation capability or minimum equipment required for the flight is degraded Correct answer.
  4. When the pilot wishes to request a different cruising speed

Explanation

Any failure or degradation of equipment essential for IFR flight, such as navigation or communication equipment, must be reported to ATC without delay. Routine items such as early arrival or speed requests are handled as normal requests.

Question 17Air Law and ATC Procedures (instrument flight rules)

An IFR aircraft is cleared for a VOR approach at a Mauritian aerodrome. The approach procedure specifies a final approach course of 145 degrees and a minimum descent altitude (MDA) of 620 ft. What does the MDA represent?

  1. The altitude at which the aircraft must be fully configured for landing
  2. The altitude at which the controller assumes responsibility for terrain clearance
  3. The altitude at which a go-around must always be initiated
  4. The lowest altitude to which descent is authorised until the required visual reference is established Correct answer.

Explanation

For a non-precision approach, the MDA is the lowest altitude to which descent is authorised until the required visual reference is established and the aircraft is positioned to land. The pilot may descend below MDA only when able to continue the approach visually.

Question 18Air Law and ATC Procedures (instrument flight rules)

Two IFR aircraft are on converging tracks at the same level in controlled airspace. Which separation standard must the controller apply when radar separation is used?

  1. A minimum of 10 NM at all times regardless of system
  2. The prescribed radar separation minimum appropriate to the radar system and airspace Correct answer.
  3. No separation is required once both aircraft are radar identified
  4. A minimum of 3 NM only inside the terminal area

Explanation

Where radar separation is applied, the controller uses the prescribed minimum appropriate to the radar system, the airspace and the position of the aircraft, commonly 5 NM in much en-route airspace and 3 NM in terminal areas where approved. A single fixed value for all situations is incorrect.

Question 19Air Law and ATC Procedures (instrument flight rules)

An IFR aircraft experiences a pressurisation failure and must descend immediately. What is the correct priority of action?

  1. Continue to the destination at the assigned level
  2. Squawk 7700 only after landing
  3. Advise ATC of the emergency and descend to a safe level, obtaining a revised clearance as soon as practicable Correct answer.
  4. Maintain the assigned level until a written clearance is received

Explanation

In an emergency the pilot may deviate from the clearance to the extent necessary, must inform ATC as soon as practicable, and should obtain a revised clearance when able. Declaring the emergency and descending takes precedence over waiting for a written clearance.

Question 20Air Law and ATC Procedures (instrument flight rules)

A pilot flying IFR in Mauritius airspace is instructed to 'hold at the Flic en Flac VOR, maintain FL140, inbound track 270, right-hand pattern, one-minute legs'. Which statement correctly describes the holding pattern to be flown?

  1. The aircraft holds on the 270-degree inbound track, turns right, with one-minute legs at FL140 Correct answer.
  2. The aircraft holds at FL140 with legs of two minutes
  3. The aircraft holds on the 270-degree outbound track with left turns
  4. The aircraft holds on the 090-degree inbound track with left turns

Explanation

The instruction specifies the inbound track (270 degrees), the direction of turns (right-hand), the leg length (one minute) and the level (FL140). The pilot must join and fly the pattern exactly as cleared, adjusting for wind to remain on the inbound track.

Question 21Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

In a light twin-engine aeroplane certified for IFR operations, the primary purpose of the constant-speed propeller feathering system is to:

  1. Maintain a fixed RPM during descent without pilot input
  2. Reduce drag from a windmilling propeller after an engine failure Correct answer.
  3. Provide reverse thrust for landing rollout
  4. Increase take-off thrust by raising blade angle

Explanation

Feathering rotates the blades to approximately the flight line so the propeller stops rotating and presents minimum drag. This is critical for single-engine performance after an engine failure in IFR flight, where climb gradient and drift-down capability depend on reducing asymmetric drag.

Question 22Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

During an IFR climb in icing conditions, the pitot-static system's static ports begin to ice over. The most immediate indication in the cockpit will be:

  1. Altimeter and vertical speed indications becoming erroneous Correct answer.
  2. Airspeed reading increasing toward the never-exceed speed
  3. Airspeed dropping to zero
  4. Turn coordinator showing a constant rate of turn

Explanation

Blocked static ports trap pressure in the static line, so the altimeter, vertical speed indicator and airspeed indicator all receive a false static reference. The airspeed indicator behaves like an altimeter, and the altitude and VSI readings become unreliable, which is hazardous in IFR without a standby static source.

Question 23Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

An aircraft's altimeter is set to the standard pressure setting of 1013.25 hPa. When flying at a constant indicated altitude from a high-pressure area toward a low-pressure area, the true altitude will:

  1. Remain constant because indicated altitude is unchanged
  2. Oscillate depending on the outside air temperature
  3. Increase gradually as the aircraft flies toward the low
  4. Decrease below the indicated altitude Correct answer.

Explanation

With a fixed subscale setting, the altimeter indicates the pressure altitude of the air it samples. Flying toward lower pressure at a constant indicated altitude means the aircraft is descending in real terms, so true altitude decreases. This is the basis of the rule 'high to low, look out below'.

Question 24Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

In a turbocharged piston engine, the function of the waste gate is to:

  1. Limit fuel flow at high altitude
  2. Prevent propeller overspeed during descent
  3. Regulate exhaust gas flow through the turbine to control manifold pressure Correct answer.
  4. Cool the induction air before it enters the cylinders

Explanation

The waste gate bypasses exhaust gas around the turbocharger turbine. By modulating exhaust flow, it controls turbine speed and therefore compressor output, which sets manifold pressure. Proper waste gate operation is essential for maintaining engine power at altitude in IFR cruise.

Question 25Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

A pilot flying IFR in a pressurised aircraft notices the cabin altitude climbing steadily while cabin vertical speed shows a climb, with no change in aircraft altitude. The most likely cause is:

  1. A failed airspeed indicator
  2. A jammed cabin altitude selector at the selected altitude
  3. A failed cabin pressure controller allowing the outflow valve to open Correct answer.
  4. An increase in bleed air temperature

Explanation

Cabin altitude is maintained by controlling the outflow valve to balance bleed-air inflow against outflow. If the valve opens or the controller fails, cabin pressure leaks away and cabin altitude climbs even though aircraft altitude is constant. Recognising this early allows the crew to descend or use oxygen before hypoxia develops.

Question 26Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

The attitude indicator in a light aircraft is typically driven by:

  1. An electrically driven gyroscope with three degrees of freedom
  2. A vacuum-driven gyroscope with two degrees of freedom Correct answer.
  3. A magnetic flux valve sensing the earth's field
  4. A pitot-static pressure differential

Explanation

The attitude indicator uses a gyroscope that is free to move in pitch and roll (two degrees of freedom) while spinning about its vertical axis, and it is normally spun by vacuum or pressure air. This allows it to display pitch and bank relative to the horizon regardless of aircraft attitude.

Question 27Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

During an IFR approach in a reciprocating-engine aircraft, the pilot selects full carburettor heat. The expected effect on the engine is:

  1. A decrease in manifold pressure and a slight enrichment of the mixture Correct answer.
  2. An increase in manifold pressure and a leaner mixture
  3. No change in manifold pressure but an increase in RPM
  4. A rise in oil temperature with no change in mixture

Explanation

Carburettor heat routes warm air from around the exhaust into the induction system. The less dense warm air reduces manifold pressure, and because the carburettor meters fuel by mass airflow, the mixture becomes slightly richer. Pilots must anticipate this power loss during approach and go-around planning.

Question 28Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

A pilot is flying IFR with the autopilot engaged in altitude hold. The autopilot's altitude hold function primarily uses input from:

  1. The attitude indicator's roll axis
  2. The static pressure source and the altitude selector Correct answer.
  3. The turn coordinator's rate of turn
  4. The magnetic heading indicator

Explanation

Altitude hold compares the selected altitude with the actual pressure altitude derived from the static system, then commands pitch changes to reduce the error. It relies on a reliable static source, so a static blockage can cause the autopilot to fly an incorrect altitude.

Question 29Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

In a multi-engine aeroplane, the critical engine is the engine whose failure most adversely affects performance. For a conventional twin with both propellers rotating clockwise when viewed from the cockpit, the critical engine is:

  1. The right engine
  2. The engine with the higher oil temperature
  3. Either engine, because the effect is symmetrical
  4. The left engine Correct answer.

Explanation

With clockwise rotation, the downward-moving blade of the right engine is closer to the fuselage, so the right engine's P-factor arm is longer. When the left engine fails, the asymmetric thrust moment from the right engine is greater, making the left engine the critical one.

Question 30Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

A pilot notices that the fuel pressure gauge is reading low in cruise while the fuel flow gauge reads normal and the engine runs smoothly. The most appropriate initial action is to:

  1. Immediately shut down the engine and feather the propeller
  2. Switch off the electric fuel pump to reduce pressure
  3. Assume the gauge is faulty and continue without further checks
  4. Cross-check the fuel pressure gauge against fuel flow, engine parameters and tank quantity before acting Correct answer.

Explanation

A single anomalous indication should be verified against related parameters before corrective action. Normal fuel flow, smooth running and stable tank quantity suggest a gauge or sensor fault rather than an actual supply problem, but the cross-check confirms this. Premature shutdown in IFR flight introduces greater risk than a confirmed gauge discrepancy.

Question 31Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

The purpose of the alternate static source in an IFR-equipped aircraft is to:

  1. Allow the pilot to select a second altimeter setting
  2. Supply backup electrical power to the gyroscopic instruments
  3. Provide a static pressure reference if the primary static ports become blocked Correct answer.
  4. Bypass the pitot heat system

Explanation

The alternate static source opens a valve to cabin pressure so that the altimeter, airspeed indicator and VSI continue to operate if the external static ports are blocked. Because cabin pressure is usually slightly lower than ambient, the indications are subject to small errors that the pilot must allow for.

Question 32Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

During a climb in a light aircraft, the pilot observes that the turn coordinator shows a standard-rate turn to the left while the attitude indicator shows wings level. An independent standby attitude indicator confirms a steady left bank, and an independent heading reference confirms a sustained left turn. The most likely explanation is:

  1. The turn coordinator has failed electrically
  2. The attitude indicator is giving an erroneous wings-level indication Correct answer.
  3. The magnetic heading indicator is misaligned
  4. The aircraft is in a slip

Explanation

The independent bank and heading references confirm that the aircraft is banked and turning left, so the wings-level attitude indication is unreliable. Use reliable instruments and the applicable failure procedure. Caging or resetting is appropriate only when permitted by the instrument's design and the aircraft's operating procedures.

Question 33Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

In a turbine-engine aircraft, the primary purpose of the engine anti-ice system is to:

  1. De-ice the propeller blades
  2. Increase fuel flow during icing conditions
  3. Cool the engine bleed air before it enters the cabin
  4. Prevent ice build-up on the engine intake and compressor front frame Correct answer.

Explanation

Engine anti-ice uses hot bleed air to keep the intake lip and front frame above freezing, preventing ice ingestion and compressor damage. Ice shedding into the engine can cause surge or damage, so anti-ice is used whenever icing conditions are likely in IFR flight.

Question 34Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

The manifold pressure gauge in a normally aspirated piston engine is essentially measuring:

  1. The absolute pressure in the induction manifold Correct answer.
  2. The fuel pressure at the carburettor inlet
  3. The exhaust back pressure at the turbocharger
  4. The pressure difference between the pitot and static sources

Explanation

Manifold pressure is an absolute pressure reading of the air in the induction manifold downstream of the throttle. With the engine stopped it reads ambient pressure, and it falls as the throttle closes or altitude increases, which is why it is a key power reference in IFR cruise and approach planning.

Question 35Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

An aircraft is flying IFR at FL180 with the cabin pressurised to 8,000 ft. The cabin altitude warning activates. The crew's immediate priority is to:

  1. Don oxygen masks, establish communications and descend to a safe cabin altitude Correct answer.
  2. Turn off all bleed air sources
  3. Increase cabin pressure selection to maximum
  4. Reduce airspeed to minimise cabin leak rate

Explanation

A cabin altitude warning indicates that cabin pressure is being lost, and hypoxia is an immediate threat. The crew must don oxygen, establish crew communication, and initiate a descent to a cabin altitude where oxygen is not required, following the emergency descent procedure.

Question 36Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

In a light aircraft, the heading indicator must be periodically realigned with the magnetic compass because:

  1. The heading indicator is driven by the pitot-static system
  2. The gyroscope precesses over time and does not sense the earth's magnetic field Correct answer.
  3. The gyroscope is affected by engine RPM
  4. The magnetic compass is more accurate in turns

Explanation

The heading indicator uses a gyroscope that maintains its orientation in space but is subject to real and apparent precession. It has no magnetic sensing element, so it must be reset to the magnetic compass at intervals during straight and level flight.

Question 37Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

A turbocharged aircraft is climbing through FL200 when the pilot observes that manifold pressure cannot be maintained at the selected value despite full throttle. The most likely explanation is:

  1. The waste gate is stuck fully closed
  2. The fuel mixture is too rich
  3. The turbocharger has reached its critical altitude and cannot provide further boost Correct answer.
  4. The propeller governor is malfunctioning

Explanation

Critical altitude is the highest altitude at which the turbocharger can maintain the selected manifold pressure at full throttle. Above it, the compressor cannot deliver the required density, so manifold pressure falls. This is a normal limitation that must be anticipated in climb and cruise planning.

Question 38Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

The function of the fuel/air mixture control in an aircraft operating at high altitude is to:

  1. Regulate cabin pressure
  2. Maintain the correct fuel-to-air ratio as air density decreases Correct answer.
  3. Control the turbocharger waste gate
  4. Set the propeller blade angle

Explanation

As altitude increases, air density falls while fuel flow remains metered by volume, so the mixture becomes richer. The mixture control allows the pilot to lean the mixture to restore the correct fuel-to-air ratio, which improves combustion efficiency and prevents fouling in IFR cruise.

Question 39Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

During an IFR flight, the pilot observes that the ammeter shows a continuous discharge with the alternator switch on. The most appropriate action is to:

  1. Reduce electrical load, check the alternator circuit breaker and plan for a diversion or landing Correct answer.
  2. Increase engine RPM to maximum and continue the flight
  3. Ignore the indication because the battery will recharge
  4. Turn off all avionics immediately

Explanation

A continuous discharge indicates that the alternator is not supplying the bus, and the battery is depleting. Reducing load conserves battery capacity for essential equipment, while checking the circuit breaker and planning to land reduces the risk of losing electrical power in IMC.

Question 40Instrument Flight: Aircraft General Knowledge (systems relevant to IFR flight)

The standby attitude indicator in an IFR-equipped aircraft is typically powered by:

  1. A dedicated electrical source independent of the main electrical system Correct answer.
  2. The main alternator bus only
  3. The vacuum system shared with the main attitude indicator
  4. The pitot-static system

Explanation

Standby instruments must remain available if the main electrical or vacuum systems fail, so the standby attitude indicator is powered by a separate source such as a dedicated battery or independent inverter. This ensures attitude information is available for partial-panel flight.

Question 41Instrument Flight: Flight Performance and Planning

Under ISA conditions, what is the standard atmospheric pressure and temperature at mean sea level, the datum used for aircraft performance planning?

  1. 1013.25 hPa and 15 °C Correct answer.
  2. 1000 hPa and 15 °C
  3. 1013.25 hPa and 0 °C
  4. 1013.25 hPa and 20 °C

Explanation

The International Standard Atmosphere fixes mean sea level pressure at 1013.25 hPa and temperature at 15 °C, with a lapse rate of about 1.98 °C per 1000 ft up to the tropopause. All pressure-altitude and density-altitude computations in performance planning start from these datum values.

Question 42Instrument Flight: Flight Performance and Planning

An aerodrome has an elevation of 4000 ft and the QNH is 1013 hPa. With the ISA temperature at that level being about 7 °C, what is the density altitude when the actual temperature is 27 °C?

  1. About 5400 ft
  2. About 4000 ft
  3. About 8000 ft
  4. About 6800 ft Correct answer.

Explanation

With QNH at the standard value, pressure altitude equals aerodrome elevation, 4000 ft. The temperature is 20 °C above ISA, and the rule of thumb adds roughly 120 ft of density altitude per degree Celsius above ISA, giving about 2400 ft on top of 4000 ft, or approximately 6400–6800 ft.

Question 43Instrument Flight: Flight Performance and Planning

Compared with a cold day, what is the effect of a high outside air temperature on take-off ground roll and on engine power output for a normally aspirated piston engine?

  1. Ground roll increases and power output increases
  2. Ground roll increases and power output decreases Correct answer.
  3. Ground roll decreases and power output decreases
  4. Ground roll decreases and power output increases

Explanation

Warm air is less dense, so the engine inducts fewer kilograms of air per cycle and produces less power, while the wing and propeller are also less effective. The combination of reduced thrust and higher true airspeed for the same indicated lift means a longer ground roll.

Question 44Instrument Flight: Flight Performance and Planning

When planning a departure from a runway where the reported wind is a direct tailwind, how should the take-off distance be obtained?

  1. Enter the chart with the tailwind component and read the increased distance Correct answer.
  2. Subtract 10 per cent from the headwind chart value
  3. Divide the still-air distance by the tailwind component in knots
  4. Use the still-air chart value without correction

Explanation

Approved take-off charts include a tailwind section, and the tailwind component must be entered directly to obtain the increased ground roll and screen height distance. Tailwind increases ground roll significantly, and many operators impose a maximum permitted tailwind limit.

Question 45Instrument Flight: Flight Performance and Planning

What is the primary reason for applying a 1.15 factor to the demonstrated landing distance when calculating the landing distance required at a destination aerodrome?

  1. To compensate for a downslope on the runway
  2. To allow for a touchdown before the threshold
  3. To account for pilot technique and braking variations on a dry runway Correct answer.
  4. To convert pressure altitude into density altitude

Explanation

The certified landing distance is multiplied by 1.15 to cover normal variations in approach speed, touchdown point and braking technique on a dry runway. Wet or contaminated runways require a further factor of 1.15 in many regulatory schemes, giving 1.43 overall.

Question 46Instrument Flight: Flight Performance and Planning

An aircraft must clear a 50 ft obstacle at the end of the take-off distance available. What does the term 'take-off distance required' normally include?

  1. Ground roll only
  2. Ground roll plus the distance to reach 35 ft
  3. The balanced field length only
  4. Ground roll plus the distance to reach 50 ft Correct answer.

Explanation

Take-off distance required is measured from the start of the roll to the point where the aircraft reaches 50 ft above the runway surface, so it includes both the ground roll and the airborne segment. Ground roll alone is the take-off run, which is a different chart value.

Question 47Instrument Flight: Flight Performance and Planning

During a climb at a constant indicated airspeed, what happens to the true airspeed and the rate of climb as the aircraft climbs into less dense air?

  1. True airspeed increases and rate of climb increases
  2. True airspeed stays constant and rate of climb stays constant
  3. True airspeed increases and rate of climb decreases Correct answer.
  4. True airspeed decreases and rate of climb increases

Explanation

Holding a constant indicated airspeed means true airspeed rises as density falls, because the same dynamic pressure corresponds to a higher true speed. Excess thrust available for climbing reduces with altitude, so the rate of climb decreases until the absolute ceiling is reached.

Question 48Instrument Flight: Flight Performance and Planning

How does an increase in aircraft mass affect the best angle of climb speed (Vx) and the best rate of climb speed (Vy) for a light twin?

  1. Vx decreases and Vy increases
  2. Vx increases and Vy decreases
  3. Both Vx and Vy decrease
  4. Both Vx and Vy increase Correct answer.

Explanation

A heavier aircraft needs more lift and therefore a higher speed for any given angle of attack, so both the best-angle and best-rate speeds increase with mass. The excess thrust available is also reduced, so the actual climb gradient and rate deteriorate even though the speeds are higher.

Question 49Instrument Flight: Flight Performance and Planning

A flight is planned along a route of 480 NM at a true airspeed of 160 kt with a direct headwind of 40 kt. What is the required flight time in still-air terms and with the wind?

  1. 3 h 30 min still air and 4 h 00 min with wind
  2. 2 h 40 min still air and 3 h 00 min with wind
  3. 3 h 00 min still air and 4 h 00 min with wind Correct answer.
  4. 3 h 00 min still air and 3 h 20 min with wind

Explanation

Still-air time is 480 divided by 160, which equals 3 hours. With a 40 kt headwind the ground speed is 120 kt, and 480 divided by 120 equals 4 hours, so the wind adds a full hour.

Question 50Instrument Flight: Flight Performance and Planning

What is the purpose of the point of no return (PNR) in flight planning?

  1. The point at which the aircraft reaches its cruising level
  2. The point at which the aircraft must start its descent
  3. The point beyond which the aircraft cannot return to the departure aerodrome with the fuel remaining Correct answer.
  4. The point at which the alternate aerodrome becomes the destination

Explanation

The PNR is computed so that the fuel needed to fly from that point back to the departure aerodrome equals the fuel available, accounting for the outbound and inbound wind components. Beyond it, a return is no longer possible and the flight must continue to another suitable aerodrome.