01/2021

Question 1

RNAV

Answer 1

• Area Navigation (RNAV) is a key enabler of Performance Based Navigation (PBN). It is a family of navigation specifications which permit the operation of aircraft on any desired flight path; RNAV allows aircraft positions to be continuously determined wherever the aircraft are within the coverage of navigation aids.
• (GPS), brought a new opportunity to derive an accurate three-dimensional (VNAV) position as well as a highly accurate two-dimensional (LNAV) position over an area not restricted by the disposition of ground transmitters.
• RNAV of sufficient accuracy is seen as ultimately providing a replacement for all ground-based navigation aids.
• (ICAO) PBN Manual identifies four navigation specifications under the RNAV family: RNAV 10, RNAV 5, RNAV 2 and RNAV 1.
• RNAV 10, designated as RNP 10 in the ICAO’s PBN Manual, is an RNAV specification for oceanic and remote continental navigation applications.
• RNAV 5, also referred to as Basic Area Navigation (B-RNAV), has been in use In Europe since 1998 and is mandated for aircraft using higher level airspace. It requires a minimum navigational accuracy of +/- 5nm for 95% of the time and is not approved for use below MSA.
• RNAV 2 supports navigation in en-route continental airspace in the United States.
• RNAV 1 is the RNAV specification for Precision Area Navigation (P-RNAV). It requires a minimum navigational accuracy of +/- 1nm for 95% of the time.
• Under the PBN concept, in addition to RNAV navigation specifications there exists the required navigation performance (RNP) family of navigation specifications. RNAV and RNP navigation specifications are substantially very similar; they only differ in relation to the performance monitoring and alerting requirement which applies to RNP navigation specifications. This means that if the RNP system does not perform the way it should then an alert should be provided to the flight crew.

Question 2

PBN

Answer 2

• It is a new concept based on the use of Area Navigation (RNAV) systems.
• ICAO PBN Manual (Doc 9613) definition is: Area navigation based on performance requirements for aircraft operating along an ATS route, on an instrument approach procedure or in a designated airspace.
• PBN represents a fundamental shift from sensor-based to performance-based navigation and offers a number of advantages over the sensor-specific method of developing airspace and obstacle clearance criteria, i.e.:
  
  • reduces the need to maintain sensor-specific routes and procedures, and their associated costs;
  • avoids the need for developing sensor-specific operations with each new evolution of navigation systems, which would be cost-prohibitive;
  • allows for more efficient use of airspace (route placement, fuel efficiency and noise abatement);
  • clarifies how RNAV and RNP systems are used; and
  • facilitates the operational approval process for operators by providing a limited set of navigation specifications intended for global use.
• Currently, the PBN approach procedure naming convention is not standardised throughout the world and is inconsistent with the PBN navigation specifications.
• From 1 December 2022, only the term RNP will be permitted, e.g. RNP RWY XX or RNP RWY XX (AR) will be acceptable while RNAV, GPS and GNSS will not be.

Question 3

CVR

Answer 3

• A device used to record the audio environment in the flight deck for accidents and incident investigation purposes.
• Fixed-wing aeroplanes with a maximum take-off mass of more than 5 700 kg and for which the certificate of airworthiness is first issued after 1 January 2003 shall be equipped with a CVR with a recording duration of two hours.

Question 4

RVSM equipment

Answer 4

• An operator shall ensure that aeroplanes operated in RVSM airspace are equipped with:
  
  • Two independent altitude measurement systems;
  • An altitude alerting system;
  • An automatic altitude control system; and
  • A secondary surveillance radar (SSR) transponder with altitude reporting system that can be connected to the altitude measurement system in use for altitude keeping.

Question 5

MSA

Answer 5

• The Minimum Sector Altitude (MSA) is the lowest altitude which may be used which will provide a minimum clearance of (1 000 ft) above all objects located in the area contained within a sector of a circle of (25 NM) radius centred on a radio aid to navigation.

Question 6

RVSM contingency

Answer 6

• Contingency procedures when unable to maintain RVSM
  
  • The pilots shall notify ATC of any equipment failure, weather hazards such as severe turbulence etc., which may affect the ability to maintain the cleared level or the RVSM requirements. When an aircraft operating in RVSM Airspace encounters severe turbulence due to weather or wake vortex which the pilot believes will impact the aircraft’s capability to maintain its cleared flight level, the pilot shall inform ATC. ATC is required to establish either an appropriate horizontal separation minimum, or an increased vertical separation minimum of 2000ft;
  • Where a meteorological forecast is predicting severe turbulence within the RVSM Airspace, ATC shall determine whether RVSM should be suspended, and, if so, the period of time, and specific flight level(s) and/or area.
  • When notified by ATC of an assigned altitude deviation of more than 300ft (90 m), the pilot shall take action to return to the cleared level as quickly as possible.
  • In the event of a pilot advising that the aircraft is no longer capable of RVSM operations, it is particularly important that the first ATS unit made aware of the failure performs the necessary co-ordination with subsequent ATS units.

Question 7

RVSM

Answer 7

• A program was initiated by ICAO in 1982 involving worldwide studies to assess the feasibility of a reduction of the Vertical Separation Minima (VSM) above FL290 from 2,000 feet to 1,000 feet.
• The principal benefits which the implementation of the reduced VSM were expected to provide were:
  
  • A theoretical doubling of the airspace capacity, between FL290 and FL410; and
  • The opportunity for aircraft to operate at closer to the optimum flight levels with the resulting fuel economies.
• An operator shall ensure that aeroplanes operated in RVSM airspace are equipped with:
  
  • Two independent altitude measurement systems;
  • An altitude alerting system;
  • An automatic altitude control system; and
  • A secondary surveillance radar (SSR) transponder with altitude reporting system that can be connected to the altitude measurement system in use for altitude keeping.
• Contingency procedures when unable to maintain RVSM
  
  • The pilots shall notify ATC of any equipment failure, weather hazards such as severe turbulence etc., which may affect the ability to maintain the cleared level or the RVSM requirements. When an aircraft operating in RVSM Airspace encounters severe turbulence due to weather or wake vortex which the pilot believes will impact the aircraft’s capability to maintain its cleared flight level, the pilot shall inform ATC. ATC is required to establish either an appropriate horizontal separation minimum, or an increased vertical separation minimum of 2000ft;
  • Where a meteorological forecast is predicting severe turbulence within the RVSM Airspace, ATC shall determine whether RVSM should be suspended, and, if so, the period of time, and specific flight level(s) and/or area.
  • When notified by ATC of an assigned altitude deviation of more than 300ft (90 m), the pilot shall take action to return to the cleared level as quickly as possible.
  • In the event of a pilot advising that the aircraft is no longer capable of RVSM operations, it is particularly important that the first ATS unit made aware of the failure performs the necessary co-ordination with subsequent ATS units.
• RVSM related phraseology
  
  • Pilot reporting severe turbulence / weather affecting ability to maintain RVSM height keeping requirements - UNABLE RVSM DUE TURBULENCE
  • Pilot reporting equipment degradation below RVSM requirements - UNABLE RVSM DUE EQUIPMENT

Question 8

ILS

Answer 8

• Instrument Landing System (ILS) is defined as a precision runway approach aid based on two radio beams which together provide pilots with both vertical and horizontal guidance during an approach to land.
• An Instrument Landing System is a precision runway approach aid employing two radio beams to provide pilots with vertical and horizontal guidance during the landing approach.
• The ILS LOC aerials are normally located at the end of the runway.
• The GS aerials are usually located so that the glide-slope provides a runway threshold crossing height of about 50 ft.
• Typically, the first marker beacon (the Outer Marker) would be located about 5 NM from touch-down while the second marker beacon (the Middle Marker) would be located about 1 NM from touch-down.
• Special categories of ILS approach are defined which allow suitably qualified pilots flying suitably equipped aircraft to suitably equipped runways using appropriately qualified ILS systems to continue an ILS approach without acquiring visual reference to a lower DH than the Category I standard of 200 feet above runway threshold elevation and do so when a lower reported RVR than the 550 metres usually associated with Category I:
  
  • Category II permits a DH of not lower than 100 ft and an RVR not less than 300 m;
  • Category IIIA permits a DH below 100 ft and an RVR not below 200 m;
  • Category IIIB permits a DH below 50 ft and an RVR not less than 50 m;
  • Category IIIC is a full auto-land with roll out guidance along the runway centreline and no DH or RVR limitations apply. This Category is not currently available routinely primarily because of problems which arise with ground manoeuvring after landing.
• The special conditions which apply for Category II and III ILS operation cover aircraft equipment; pilot training and the airfield installations. In the latter case, both function, reliability and operating procedures are involved. An example of the latter is the designation of runway holding points displaced further back from the runway so as to ensure that aircraft on the ground do not interfere with signal propagation. Reliability requirements for Category II and III ILS include a secondary electrical power supply which should be fully independent of the primary one.

Question 9

FANS

Answer 9

• The Future Air Navigation System (FANS) is an avionics system which provides direct data link communication between the pilot and the air traffic controller. The communications include air traffic control clearances, pilot requests and position reporting.[1] In the FANS-B equipped Airbus A320 family aircraft, an Air Traffic Services Unit (ATSU) and a VHF Data Link radio (VDR3) in the avionics rack and two data link control and display units (DCDUs) in the cockpit enable the flight crew to read and answer the controller–pilot data link communications (CPDLC) messages received from the ground.[2]

Question 10

ADS-B outputs?

Answer 10

• A means by which aircraft, aerodrome vehicles and other objects can automatically transmit and/or receive data such as identification, position and additional data, as appropriate, in a broadcast mode via a data link.
• ADS-B is a Surveillance technique that relies on aircraft or airport vehicles broadcasting their identity, position and other information derived from on board systems (GNSS etc.). This signal (ADS-B Out) can be captured for surveillance purposes on the ground (ADS-B Out) or on board other aircraft in order to facilitate airborne traffic situational awareness, spacing, separation and self-separation (ADS-B In)
• ADS-B is automatic because no external stimulus is required; it is dependent because it relies on on-board systems to provide surveillance information to other parties. Finally, the data is broadcast, the originating source has no knowledge of who receives the data and there is no interrogation or two-way contract.
• The introduction of ADS-B in the Surveillance infrastructure provides important features which can be exploited by the ATM Network:
  
  • Full “Network-wide” Surveillance coverage
    
    • Surveillance “everywhere”, i.e. no gaps from gate-to-gate
    • Air-to-air Surveillance possible, i.e. traffic situational awareness picture available on board
    • The aircraft is integral part of the Network
    • Surveillance data provided directly from on-board systems
  • High performance
  • Improved safety
  • Increased capacity
  • Cost-efficiency
    
    • Reduced cost of the Surveillance infrastructure (ADS-B is cheaper than radar)
    • More efficient flight profiles (in areas where previously surveillance was not cost-effective)
    • Fuel savings etc.
  • Environmental sustainability (CO2 reduction)
  • Reduced RF pollution (leading to an increased viability of the 1090 MHz datalink)
  • Global Interoperability
  • Foundation for future ATC applications (spacing, separation, self-separation)
• The 1090 MHz Mode S Extended Squitter technology is used worldwide to ensure global interoperability. At local or regional level, other datalink technologies can be considered, e.g. the Universal Access Transceiver (UAT) system introduced in the USA.
• The “ADS-B Out” capability on board is enabled by transponders interfaced with the relevant avionics systems (such as GNSS, pressure altimeters etc.).
• The ADS-B data transmitted by the aircraft or airport vehicles are received by the ADS-B Ground stations.
• The ADS-B data transmitted are defined in the relevant standards and certification documents (e.g. EASA AMC 20-24 for ADS-B in Non-Radar Airspace or CS-ACNS for “ADS-B out”). They include (amongst others) the following:
  
  • Aircraft horizontal position (latitude/longitude)
  • Aircraft barometric altitude (will be the same as for the SSR)
  • Quality indicators
  • Aircraft identification:
    
    • Unique 24-bit aircraft address
    • Aircraft identification
    • Mode A code (in the case of CS ACNS for “ADS-B Out”)
  • Emergency status
  • SPI (special position indicator) when selected

Question 11

CMV

Answer 11

RVR (Runway Visual Range) is considered to be better representation of expected distance that the pilot may acquire visual cues on approach than meteorological office reported horizontal visibility. Effect of lighting intensities and background luminescence play a role when establishing an RVR.

Due to commercial or other reasons RVR may not be available at all the airports and in such cases pilot may derive RVR/CMV-Converted Meteorological Visibility by using mathematical conversions depending upon the type of approach lighting and day/night conditions.

Following table is used to calculate CMV.

CMV

Note:

Conversion of meteorological visibility to RVR is not be used:

for takeoff,
for calculating any other requred RVR minimum less than 800 m,
for visual/circling approaches,
or when reported RVR is available

Question 12

TCAS

Answer 12

• ACAS II is an aircraft system based on Secondary Surveillance Radar (SSR) transponder signals. ACAS II interrogates the Mode C and Mode S transponders of nearby aircraft (‘intruders’) and from the replies tracks their altitude and range and issues alerts to the pilots, as appropriate. ACAS II will not detect non-transponder-equipped aircraft and will not issue any resolution advice for traffic without altitude reporting transponder.
• Currently, the only commercially available implementations of ICAO standard for ACAS II (Airborne Collision Avoidance System) is TCAS II version 7.1 (Traffic alert and Collision Avoidance System). ICAO Annex 10 vol. IV states that all ACAS II units must be complaint with version 7.1 as of 1 January 2017. In Europe version 7.1 has been mandatory since 1 December 2015.
• The maximum generation time for a TA is 48 seconds before the Closest Point of Approach (CPA). For an RA the time is 35 seconds. The time scales are shorter at lower altitudes (where aircraft typically fly slower).
• ACAS III Gives TAs and RAs in vertical and/or horizontal directions. Also referred to as TCAS III and TCAS IV. Not currently implemented and unlikely to be in the near future. ICAO SARPs for ACAS III have not been developed. Currently, there are no plans to proceed with such a development.
• ACAS X, a future collision avoidance system, is currently being developed.

Question 13

GC vs. RL

Answer 13

Great Circle: A circle on the surface of the earth whose centre and radius are
those of the earth itself. It is circle of the surface of the sphere whose centre and diameter are that of earth. A plane of the great circle divides the earth in two equal parts. Great circle distance is the shortest distance along the arc of the great circle however this is not constant.
Meridian and its anti-meridian make a great circle.
Rhumb Line: Rhumb line is a regularly curved line on the surface of the earth which cuts all the meridians on the earth at same angle. It is curve concaved to the nearer pole. Rhumb line track is constant between two positions but the distance is longer.
Equator and meridian are the only two examples on the surface of the earth which are great circles as well as rhumb line.

Question 14

IDL

Answer 14

The International Date Line (IDL) is an imaginary line of demarcation on the surface of Earth that runs from the North Pole to the South Pole and demarcates the boundary between one calendar day and the next. It passes through the middle of the Pacific Ocean, roughly following the 180° line of longitude but deviating to pass around some territories and island groups.

Question 15

why is RVSM not available above FL410?

Answer 15

For flights above FL410, 2000 feet of separation is used. Which makes all flight levels odd numbered, →410, ←430, →450, ←470, →490, ←510, …

So for each direction as indicated above by arrows, it’ll be 4000 feet.

The 2000 feet separation is because the higher up you go the less accurate an altimeter becomes, so it’s for safe separation.

Question 16

GPS, why are 6 satellites needed?

Answer 16

• GPS is a space-based positioning, velocity and time system, developed and operated by the U.S. Department of Defense and composed of space, control and user segments. The space segment is composed of 21 satellites (plus three operational spares) in six orbital planes. The control segment consists of five monitor stations, three ground antennas and a master control station. The user segment consists of antennas and receiver-processors that provide positioning, velocity, and precise timing to the user. The satellites broadcast two forms of clock information, the Coarse/Acquisition code, or C/A is freely available to the public, while the restricted Precise code, or P-code is usually reserved for military applications.
• Receiver autonomous integrity monitoring (RAIM) is a technology developed to assess the integrity of global positioning system (GPS) signals in a GPS receiver system. It is of special importance in safety-critical GPS applications, such as in aviation
• GPS does not include any internal information about the integrity of its signals. It is possible for a GPS satellite to broadcast slightly incorrect information that will cause navigation information to be incorrect, but there is no way for the receiver to determine this using the standard techniques. RAIM uses redundant signals to produce several GPS position fixes and compare them, and a statistical function determines whether or not a fault can be associated with any of the signals. RAIM is considered available if 24 GPS satellites or more are operative. If the number of GPS satellites is 23 or fewer, RAIM availability must be checked using approved ground-based prediction software.
• Because RAIM operates autonomously, that is without the assistance of external signals, it requires redundant pseudorange measurements. To obtain a 3D position solution, at least four measurements are required. To detect a fault, at least 5 measurements are required, and to isolate and exclude a fault, at least six measurements are required, however often more measurements are needed depending on the satellite geometry. Typically there are seven to 12 satellites in view.

Question 17

ILS, critical vs. sensitive areas?

Answer 17

• The ILS critical area is an area of defined dimensions about the localizer and glide path antennas where vehicles, including aircraft, are excluded during all ILS operations. The critical area is protected because the presence of vehicles and/or aircraft inside its boundaries will cause unacceptable disturbance to the ILS signal-in-space
• The ILS sensitive area is an area extending beyond the critical area where the parking and/or movement of vehicles, including aircraft, is controlled to prevent the possibility of unacceptable interference to the ILS signal during ILS operations. The sensitive area is protected against interference caused by large moving objects outside the critical area but still normally within the airfield boundary.
• The main difference appears between the critical and sensitive areas appear to be that the size of the critical area is fixed (for a localizer and glide path antenna in an airport) while that of the sensitive area varies with the category of ILS and the aircraft type. In fact, the introduction of A380 led to a reassesment of ILS protection areas.

Question 18

AIRPORT, suitable vs. adequate?

Answer 18

The definition of a suitable aerodrome is where the weather is above alternate minima. An acceptable aerodrome (adequate, whatever you want to call it) is one where the weather conditions are below the alternate minima but above the landing minima.

Question 19

Balanced Field

Answer 19

Balanced Field Length (for a given takeoff weight) is defined as the distance required to accelerate to V1 and safely stop the aircraft on the remaining runway or continue the takeoff so as to reach V2 by 35 feet above the takeoff surface at the end of the runway. (reference from ISBN: 978-0-470-74077-4)

Another way to describe BFL is that TODA = ASDA, the end of the clearway is the stopway.

Question 20

TORA, TODA & ASDA

Answer 20

• CLEARWAY
  Clearway is the area beyond the runway not less than 152 meters wide, centrally located about the extended centerline of the runway and under the control of airport authorities. It is expressed as a plane extending from the end of runway with up slop not exceeding 1.25% above which no object or terrain protrudes with exception of threshold lights.
• STOPWAY
  Stopway is the area at the end of take-off runway no less wide than the runway and centered upon extended centerline of runway. This area is able to support the aircraft during an aborted take-off without causing structural damage to the aircraft.
• TORA (Take off Run Available)
  TORA is defined as length of runway suitable for takeoff run of an aircraft. If there exists a displaced threshold TORA is not equal to LDA (Landing Distance Available). On the other hand, TORA doesn’t include Stopway or Clearway.
• TODA (Take off Distance Available)
  TODA is the length of runway plus any clearway if exists. In case no clearway exists, TODA is same as TORA. In detail, TODA includes ground as well as air segments.
• ASDA (Accelerate-Stop Distance Available)
  ASDA a distance and is defined as sum of LDA/TORA (as applicable) and Stopway. In case take off is aborted the aircraft can be brought to a stop either on the runway or on Stopway. ASDA must not be used as TORA because of the structure of the Clearway area.
• LDA (Landing Distance Available)
  LDA is the portion of runway length declared available and suitable for landing of an aircraft. If there exists a displaced threshold LDA starts from beginning of displaced threshold. Otherwise beginning of the threshold is the beginning point of LDA.

Question 21

Take Off Segments

Answer 21

The Net Takeoff Flight Path for the engine failure case is divided into four segments. Three of these are climbing segments with specified minimum gradients which are dependent upon the number of engines installed on the aircraft and one is a level acceleration segment. A brief description of the four segments is as follows:

• First Segment - depending upon the regulations under which the aircraft is certified, the first segment begins either at lift-off or at the end of the takeoff distance at a screen height of 35’ and a speed of V2. On a wet runway, the screen height is reduced to 15’. Operating engines are at takeoff thrust, the flaps/slats are in takeoff configuration and landing gear retraction is initiated once safely airborne with positive climb. The first segment ends when the landing gear is fully retracted.
• Second Segment - begins when the landing gear is fully retracted. Engines are at takeoff thrust and the flaps/slats are in the takeoff configuration. This segment ends at the higher of 400’ or specified acceleration altitude. In most cases, the second segment is the performance limiting segment of the climb.
• Third or Acceleration Segment- begins at the higher of 400’ or specified acceleration altitude. Engines are at takeoff thrust and the aircraft is accelerated in level flight. Slats/flaps are retracted on speed. The segment ends when aircraft is in clean configuration and a speed of VFS has been achieved. Note that the third segment must be completed prior to exceeding the maximum time allowed for engines at takeoff thrust.
• Fourth or Final Segment - begins when the aircraft is in clean configuration and at a speed of VFS. Climb is re-established and thrust is reduced to maximum continuous (MCT). The segment ends at a minimum of 1500’ above airport elevation or when the criteria for enroute obstacle clearance have been met.
  Each segment of the one engine inoperative takeoff flight path has a mandated climb gradient requirement. For example, a gross second segment climb gradient capability of 2.4%, 2.7% or 3.0% is required for two, three and four engine aircraft respectively. Similarly, the required gross gradients for the fourth segment are 1.2%, 1.5% and 1.7% respectively.

Note that, by regulation, turns immediately after takeoff cannot be initiated below the greater of 50’AGL or one half of the aircraft wingspan and, that during the initial climb, turns are limited to 15° of bank. Turning will result in a reduction in aircraft climb capability.

Question 22

Minimum Fuel vs. Mayday Fuel

Answer 22

• The pilot-in-command shall declare a situation of fuel emergency ”MAYDAY FUEL”, when the calculated usable fuel predicted to be available upon landing at the nearest aerodrome where a safe landing can be made is less than the planned final reserve fuel. Declaration of a fuel emergency is an explicit statement that priority handling by ATC is both required and expected.
• Minimum fuel - The term used to describe a situation in which an aircraft’s fuel supply has reached a state where the flight is committed to land at a specific aerodrome and no additional delay can be accepted. (PANS-ATM, Doc 4444)
• The declaration of “MINIMUM FUEL” informs ATC that, for a specific aerodrome of intended landing, the aircraft has sufficient fuel remaining to follow the cleared routing, execute an arrival and approach procedure and land with the required fuel reserves. However, there is little or no extra fuel on board and any change to the existing clearance could result in landing with less than planned final reserve fuel. (Diversion to alternate aerodrome is usually not an option except for cases where arrival and landing at the planned aerodrome includes considerable airborne holding.) MINIMUM FUEL is not a declaration which confers any special treatment by ATC, i.e. it is not an emergency situation, but merely an information message which, before this guidance was promulgated, would have led some operators to require that their pilots to declare a PAN. However, controllers should bear in mind that an fuel emergency may arise should any additional delay occur.

Question 23

RNAV 5 vs. RNAV 10

Answer 23

• RNAV 10, designated as RNP 10 in the ICAO’s PBN Manual, is an RNAV specification for oceanic and remote continental navigation applications.
• RNAV 5, also referred to as Basic Area Navigation (B-RNAV), has been in use In Europe since 1998 and is mandated for aircraft using higher level airspace. It requires a minimum navigational accuracy of +/- 5nm for 95% of the time and is not approved for use below MSA.

Question 24

SLOP

Answer 24

PANS ATM specifies that the strategic lateral offset shall be established parallel to the designated ATS route at a distance of 1.85 km (1 NM) or 3.7 km (2 NM) to the RIGHT of the centre line relative to the direction of flight. These two “track” options become available in addition to the track centreline, not instead of it. All ATC route clearances are made without reference to the lateral offset option and flight crew do not need to obtain permission from ATC to use these offset tracks or advise ATC of their decision to do so.

Question 25

Take-Off Alternate Requirements

Answer 25

A take-off alternate aerodrome should be specified in the operational flight plan if either the meteorological conditions at the departure aerodrome are below the applicable landing minima or in case it should not be possible to return to the departure aerodrome for some other reason. For aeroplanes with two engines, such an alternate must be within one hour's flight time at the one-engine-inoperative cruising speed specified in the Aerodrome Operating Manual (AOM) or equivalent document and assuming the aircraft mass is the actual mass at take off and ISA and still-air conditions prevail. Aeroplanes with three or more engines are permitted two hours of flight time for the same purpose and under the same conditions except the all engines operating cruising speed may me used. An aerodrome may not be designated as an alternate unless the available information indicates that at the estimated time of potential use, the prevailing conditions will be at or above the applicable operating minima.

Question 26

LVP

Answer 26

Low visibility procedures (LVP) means procedures applied at an aerodrome for the purpose of ensuring safe operations during lower than standard category I, other than standard category II, category II and III approaches and low visibility take-offs. (IR-OPS Annex I) Low visibility take-off (LVTO) means a take-off with a Runway Visual Range (RVR) lower than 400 m but not less than 75 m. (IR-OPS Annex I) Note that ICAO requires LVP for all departures below 550m RVR, not just LVTO.

Question 27

LVTO

Answer 27

Low visibility take-off (LVTO) means a take-off with a Runway Visual Range (RVR) lower than 400 m but not less than 75 m. (IR-OPS Annex I)

Question 28

Q2 routes in India

Answer 28

Q-routes are designated by Q-1,Q-2,Q-3 … Q-24. These are area navigation routes with a precision of 5 nautical miles ( RNAV-5).For example: ATS Routes Q1, Q2, Q3, Q4, Q5, Q6 and Q7 Connect Delhi to Mumbai/Ahmedabad/Udaipur/Vadodara. Q8 Between Chennai and Mumbai & Q9 [RNAV 5] Between Mumbai and Chennai Q10 Between Chennai and Kolkata & Q11 [RNAV 5] Between Kolkata and Chennai Q12 Between Thiruvananthpuram & Mumbai Q13 [RNAV 5] Between Mumbai & Thiruvananthapuram Each route passes through a set of identified waypoints ( designated by a 5 character code).

Question 29

Load Factor

Answer 29

Firstly, load factor is a ratio, so there are no units to consider, even though it is often expressed as g. Secondly, it's simply the ratio of the lift provided by the lifting surfaces divided by the total weight of the aircraft.

Question 30

MEA, MORA, MOCA

Answer 30

* The MOCA is the minimum altitude for a defined segment that provides the required obstacle clearance. A MOCA is determined and published for each segment of the route. * The minimum obstacle clearance value to be applied in the primary area for the en-route phase of an IFR flight is 1000 ft (300 m). In mountainous areas, the minimum obstacle clearance applied is as follows: Terrain Elevation Obstacle Clearance 3000 ft - 5000 ft (900 m - 1500 m) 1500 ft (450 m) Greater than 5000 ft (1500 m) 2000 ft (600 m) * The Minimum Sector Altitude (MSA) is the lowest altitude which may be used which will provide a minimum clearance of 300 m (1 000 ft) above all objects located in the area contained within a sector of a circle of 46 km (25 NM) radius centred on a radio aid to navigation. (ICAO PANS-OPS/I - definitions) * The minimum en-route altitude (MEA) is the altitude for an en-route segment that provides adequate reception of relevant navigation facilities and ATS communications, complies with the airspace structure and provides the required obstacle clearance. * MEA is the lowest altitude to be flown in an airspace structure which assures: reception of navigation aids necessary to navigate accurately along the required route, two-way communication with air traffic control, safe clearance from obstacles within the sector, and conformity with any air traffic control procedures applicable within the sector.

Question 31

CP vs. PNR

Answer 31

* The Critical Point (CP), or Equal Time Point (ETP), is when an aircraft is the same flying time from 2 potential en-route diversions. Calculation of appropriate CPs aids decision making when deciding courses of action following a significant event such as an engine failure or on-board medical emergency. * DxH/(O+H) * The point during a flight at which an aircraft is no longer capable of returning to the airfield from which it took off due to fuel considerations. Beyond this point the aircraft must proceed to some other destination. * ExH/(O+H) Where: E = Safe endurance in hours, calculated by dividing fuel at take-off, minus the appropriate Min Overhead Fuel, by the average fuel burn per hour H = Groundspeed when returning to departure airfield O = Groundspeed when proceeding to destination airfield

Question 32

GRID MORA

Answer 32

* Magenta color is a valve of more then 14000 feet, green are for valve less then 14000 feet. * Grid MORA is an altitude derived by Jeppesen or provided by a State authority that provides clearance of terrain and man-made structures within a section of a chart or database defined by latitude and longitude lines.

Question 33

Polar Navigation

Answer 33

* Grid Navigation / A method of navigation using an grid overlay, appropriate to the map projection, instead of true or magnetic north for direction reference. * In the polar regions, grid navigation is based on the use of a grid, most typically oriented parallel to a specified meridian of longitude, being overlaid on the appropriate Polar Stereographic projection navigational chart. The aircraft gyro compass is aligned to this grid, either on the ground or during flight, and is corrected, as required, for change in longitude and gyro precession using celestial navigation sightings. Although any line of longitude can be used, the Prime Meridian (0 degrees) is most commonly used as the Reference (or Datum) Meridian. This iteration is often referred to as "Greenwich Grid".

Question 34

Primary Radar vs. Secondary Radar

Answer 34

* Primary radar is a system where the ground-based antenna transmits a radar pulse, then listens for the small amount of return energy that is reflected from an aircraft. The time delay between the transmission of the pulse and the receipt of the reflected return is a measure of the range. * Secondary radar requires an airborne transponder which responds to the receipt of a pulse from a ground-based antenna by transmitting a return signal. Because the transponder transmits a much stronger signal than that which is reflected off an aircraft in primary radar systems, greater range and reliability can be achieved with secondary radar and cheaper and more efficient ground equipment can be used. Additionally, information such as altitude and a code can be added to the returned signal from the transponder which is then displayed on the operator’s screen.

Question 35

KALMAN FILTERING

Answer 35

* Kalman filtering, also known as linear quadratic estimation (LQE), is an algorithm that uses a series of measurements observed over time, containing statistical noise and other inaccuracies, and produces estimates of unknown variables that tend to be more accurate than those based on a single measurement alone, by estimating a joint probability distribution over the variables for each timeframe. The filter is named after Rudolf E. Kálmán, one of the primary developers of its theory. * The algorithm works in a two-step process. In the prediction step, the Kalman filter produces estimates of the current state variables, along with their uncertainties. Once the outcome of the next measurement (necessarily corrupted with some amount of error, including random noise) is observed, these estimates are updated using a weighted average, with more weight being given to estimates with higher certainty. The algorithm is recursive. It can run in real time, using only the present input measurements and the previously calculated state and its uncertainty matrix; no additional past information is required.

Question 36

MIX IRS

Answer 36

* The FMGC position is a mix of GPS and IRS (called GPIRS), but the IRS position is aligned to the airport reference coordinate, not to the GPS position. * The difference you observe is between the FM position and the MIX IRS position. This difference is called the bias. Position Computation Each FMGC computes its own aircraft position (called the "FM position") from a MIX IRS position (see below), and a computed radio position or GPS position. The FMGS selects the most accurate position, considering the estimated accuracy and integrity of each positioning equipment. GPS/INERTIAL is the basic navigation mode provided GPS data is valid and successfully tested. Otherwise, navaids plus inertial or inertial only are used. * The FM position will move towards the GPS position in flight, if GPS is available (otherwise to the radio position): FM Position At flight initialization, each FMGC displays an FM position that is a mixed IRS/GPS position (GPIRS). At takeoff, the FM position is updated to the runway threshold position, as stored in the database, possibly corrected by the takeoff shift entered on the PERF TO page. In flight, the FM position approaches the radio position, or the GPS position, at a rate that depends upon the aircraft altitude. Note: The FM position update at takeoff is inhibited when GPS PRIMARY is active. * Bias Each FMGC computes a vector from its MIX IRS position to the radio or GPIRS position. This vector is called the "bias". Each FMGC continuously updates its bias, if a radio position, or a GPIRS position is available. * The MIX IRS position is determined from all three IRSs: MIX IRS Position Each FMGC receives a position from each of the three IRSs, and computes a mean-weighted average called the "MIX IRS" position. * Initialization The F-PLN origin airport coordinates are extracted from the FMS database. These coordinates appear on the MCDU INITA page, and are normally used for initialization. They are the airport reference coordinates. If a high navigation performance is desired, (i.e. for long-range flights without GPS and without radio navigation updates, or if low RNP operation is expected), the crew should adjust the airport reference coordinates to the gate coordinates, provided that this data is published or available on board.

Question 37

TCAS 7.1

Answer 37

* To prevent incorrect pilot responses, in version 7.0 the “Adjust vertical speed, adjust” RAs has been replaced by a new “Level off, level off” RA which requires a reduction of vertical rate to 0 ft/min. The level off is to be achieved promptly, not at the next standard flight level (e.g. FL200, FL210, etc.). The “Level off, level off” RA may be issued as an initial RA or as a weakening RA when the vertical distance between the aircraft increases. Additionally, the “Level off, level off” RA will minimise the altitude deviations induced by TCAS (level busts while “flying the green arc”), thus reducing the impact on ATC operations. * A feature has been added to the TCAS II version 7.1 logic which monitors RA compliance in coordinated encounters (i.e. when both aircraft are TCAS II equipped). When it is detected that an aircraft is not responding correctly to an RA, a reversal RA will be issued to the aircraft which manoeuvres in accordance with the RA. In single equipage encounters (i.e. when only one aircraft is TCAS II equipped), version 7.1 will recognise the situation and will issue a reversal if the unequipped threat aircraft moves in the same vertical direction as the TCAS II equipped aircraft.

Question 38

GPWS vs. eGPWS

Answer 38

1. EGPWS is safer and more advanced than GPWS. 2. EGPWS uses GPS while GPWS doesn’t. 3. EGPWS uses a terrain database that is not available in GPWS. 4. GPWS is only aware of the ground below it while EGPWS is aware of a larger area.

Question 39

Radio Aids in A320

Answer 39

* There are three identical Air Data Intertial Reference Units (ADIRU). In general ADIRU 1 and ADIRU 2 supply on-side systems and ADIRU 3 is a hot spare. Each ADIRU combines an Air Data Reference (ADR) computer and a laser gyro based Inertial Reference (IR) system. The two sub-units are completely independent. The ADR part gathers data from aircraft probes and sensors, and provides the following data to other systems: Airspeed and Mach number Temperature Barometric altitude Angle of attack Overspeed warnings The IR part provides the following data: Attitude Heading Aircraft position Track Acceleration Ground speed Flight Path Vector * FMGCs auto-tune VORs, ILSs and DMEs for position updating. The ADFs are only auto tuned under specific circumstances. Manual tuning of the aids is via the RAD NAV MCDU page. When aids are manually tuned, FMGC auto tuning continues in the background. If an ILS approach is selected the PFDs show the on-side ILS and the NDs show the off-side ILS. If both FMGCs fail, radio aids may be tuned using the nav mode of RMP1 and RMP2. The RMPs tune their on-side VORs, DMEs and ADFs. The ILS frequency tuned on either RMP is sent to both ILSs. When a NAV key is pressed on an RMP, the RADIO NAV page blanks, showing only the titles. DME information will ot be displayed on the PFD for an ILS/DME tuned on an RMP. * A standby ASI, altimeter and attitude indicator are provided to the right of the captain's ND and a pull down standby compass is fitted on top of the windshield centre post. The standby attitude indicator is the only standby instrument requiring electrical power. It will operate for approximately five minutes after a total electrical failure. * The EPGWS normal inputs are: RA1 ADIRS1 ILS1 FMGC1 LGCIU1 The basic GPWS has no forward looking capability - it mainly monitors RA1 for potentially hazerdous values or trends. * The EGPWS system provides a look ahead capability by comparing caution and warning terrain envelopes generated from a terrain database to FMGS position data and baro data from the Captain's altimeter. Both en-route terrain and runway clearance floor envelopes are provided. The extended functions are inhibited when navigation performance is LOW. * The terrain is displayed on the ND when the TERR ON ND putton on the center panel is pressed. Areas not included in the database are color coded magenta. Dotted red areas are more than 2000ft above the aircraft, dotted orange areas more than 1000ft above the aircraft and amber areas are between 1000ft above and 500ft below (250ft below with gear down) the aircraft. * EPGWS warnings are overridden by stall or windshear warnings. * There are no cockpit controls for the radio altimeters. They self test when AC power is first applied to the aircraft, then enter a standby mode. They become active at lift off and operate continuously until touchdown. * If a single radio altimeter fails, data from the remaining one will be displayed on both screens.