Navigation & Altimetry

Question 1

What is a restricted area?

Answer 1

An airspace of defined dimensions which in which the flight of aircraft is restricted in accordance with certain specified conditions.

Question 2

What are some examples of restricted and prohibited areas?

Answer 2

Nuclear power stations, HM Prisons, some Military establishments.

Question 3

What is an Emergency Controlling Authority?

Answer 3

An emergency restriction to inhibit flight in the vicinity of an emergency incident on land or sea within Uk FIRs. May be Temporary Danger Area, or Temporary Restricted Area.

Question 4

What is a Danger Area, and what types of activity may occur in one?

Answer 4

Airspace which has been notified as such within which activities dangerous to the flight of an aircraft may take place or exist at such times as may be notified.Inevitably military in nature, uses and activities may include: captive balloon sites, weapons ranges, aircraft towing targets, military aircraft flying holding patterns.Unauthorised entry into many Danger Areas is illegal.

Question 5

What is a Danger Area Crossing Service (DACS)?

Answer 5

Inflight service available for around 25% of DA’s, to enable aircraft to cross a DA if in contact with the relevant ATCU. Frequencies for contact are printed on UK ICAO Aeronautical charts.

Question 6

What is a Danger Area Activity Information Service (DAAIS)?

Answer 6

Inflight service available for 68% of DA’s, confirms status and restrictions of DA and may allow a pilot to traverse it if safe to do so. It is NOT a clearance to cross, the pilot must make a decision.

Question 7

What is a Temporary Reserved Area (TRA)?

Answer 7

Defined volume of airspace normally under the jurisdiction of one aviation authority and temporarily reserved for the specific use of another aviation authority and through which other traffic may be allowed to transit under an ATS authority.

Question 8

What is a Military Training Area (MTA)?

Answer 8

An area of Upper Airspace of defined dimensions within which intense military flying training takes place.

Question 9

What is an Area of Intense Air Activity (AIAA)?

Answer 9

Airspace within which the intensity of civil/military flying is exceptionally high or where aircraft, either singly or in combination with others, regularly participate in unusual manoeuvres.Pilots of non-participating aircraft who are unable to avoid AIAAs are to keep a good look out and are strongly advised to make use of a Radar Service if available.

Question 10

What is an Aerial Tactics Area (ATA)?

Answer 10

Airspace of defined dimensions designated for aerial combat training, within which high energy manoeuvres are regularly practiced by aircraft formations.Pilots of non-participating aircraft who are unable to avoid these areas are strongly advised to make use of a surveillance service.

Question 11

What is an Air-to-Air Refuelling Area (AARA)?

Answer 11

Airspace of defined dimensions within which air-to-air refuelling takes place under radar service.

Question 12

What is the UK Military Low Flying System?

Answer 12

Military low flying occurs in most parts of the U.K. up to 2000ft. However the greatest concentration is between 250-500ft and civil pilots are advised to avoid flying in that height band wherever possible.Military aircraft are considered to be low flying when below 500ft for light propeller driven aircraft and helicopters, or below 2000ft for any other fixed wing aircraft.

Question 13

What is a High Intensity Radio Transmission Area (HIRTA)?

Answer 13

Airspace of defined dimensions within which there is radio energy of an intensity which may cause interference with, and on rare occasions damage to, communications and navigation.

Question 14

What is a Land-based Air Navigation Obstacle?

Answer 14

Any building or work, including waste heaps, which is at or exceeds 300ft agl.

Question 15

What is an Aerodrome Obstacle?

Answer 15

An obstacle that is located on an area intended for the surface movement of aircraft, or that extends above a defined surface intended to protect aircraft in flight.

Question 16

What is an En-route Obstacle?

Answer 16

Those located outside or beyond the the areas referred to for Aerodrome Obstacles.

Question 17

What should an ATSO do if receiving the information that a captive balloon has broken free?

Answer 17

Telephone the appropriate ACC, stating the type and position of the balloon, whether carrying any person, direction and speed of drift and the length of cable that may still be attached to the balloon.

Question 18

What are the two types of Danger Area and how are they shown on a chart?

Answer 18

Scheduled: Solid red outline and red hashing- always in effect during the specified times.Notified: Dotted red outline and red hashing- only in effect when notified.

Question 19

What is a Bird Sanctuary?

Answer 19

Airspace of defined dimensions within which large colonies of birds are known to breed.

Question 20

What is the Civil Aircraft Notification Procedure (CANP)?

Answer 20

Some civil aircraft operators have a requirement to fly at a low level when carrying out authorised aerial work (below 1000ft).These operators are strongly recommended to notify details of this to a military contact who can inform them of any operations in the vicinity and pass there position on to relevant military aircraft.

Question 21

What is a prohibited area?

Answer 21

An airspace of defined dimensions within which the flight of aircraft is prohibited.

Question 22

What is a VOR and how does it work? What are its limitations?

Answer 22

Very High Frequency Omni-Directional Range- En-route and terminal navigation aid.- Instrument Approach Aid- Works by comparing the phase of two signals- reference and variable. Comparison of the signals provides 360 radials spaces at 1 degree intervals. (360°= north, 45°= north east etc.)- Shows direction to/from VORNominally lone of sight range, max range governed by aircraft altitude and VOR elevation. Accurate to +/- 1°. Limitations: Provides no distance information. Large site required. Expensive to build and maintain.

Question 23

What is a DME and how does it work? What are its limitations?

Answer 23

Direction Measuring Equipment UHFTransponder (air-ground interrogation and ground-air response). Classed as an SSR as it can differentiate between aircraft’s interrogations. En route and approach aid. Maximum range is line-of-sight, pilot must consider DOC (designated operational coverage). In en route phase the minimum indicated range is the aircrafts height in Nm when over the DME. Accuracy 0.2NmLimitations: Inaccuracy caused by ‘slant range’ (can’t distinguish between vertical and lateral distance). No bearing information, associated NAVAID required.

Question 24

What is a TACAN?

Answer 24

A military en route and approach aid, a combination of a VOR and DME. UHF. Civil aircraft can only use the DME element (DMET). Range same as VOR/DME. Accuracy 0.2Nm.

Question 25

What is an NDB and what are its limitations?

Answer 25

Non-Directional BeaconRadio Transmission in all directions. ADF shows direction of NDB from the aircraft. MF en route and approach aid. Max range 50Nm. Less accurate than VOR/DME and variable. Limitations:- Static interference from thunderstorms/electrical discharge. - Station interference (other radio waves eg commercial radio)- Night effect- sky waves refract further- Coastal refraction- different propagation properties of water/air- Mountain effect- Quadrantal error- induced signals along airframe confusing the ADF. - No failure warning.

Question 26

What is an ILS , how does it work and what are its limitations?

Answer 26

Instrument Landing SystemOverlapping beams used to indicate correct approach. Localiser (VHF) provides azimuth guidance, glide path (UHF) provides elevation guidance. Precision Approach Aid.Range and Accuracy:Localiser 25Nm at 10° either side of the path, to 0.5°Glide path 10Nm at 8° either side of the path, to 0.14°Limitations:Beams must be protected.Expensive to build and maintain. Mirrored Glidepaths- encountered at angles that are multiples of the correct glidepath angle, leads to reversed fly-up/fly-down commands. (avoided by intercepting from below)False localisers- encountered outside of DOC (avoided by not intercepting until in DOC). ILS categories, RVR and Decision Height:Cat 1 - 550m - 200ftCat 2 - 250m - 100ftCat 3a - 200m - NilCat 3b - 50m - NilCat 3c - 0m - Nil

Question 27

What is an MLS, how does it work and what are its limitations?

Answer 27

Microwave Landing SystemTime Reference Scanning Beam (TRSB), microwave band. Precision Approach Aid, allows curved approach. Range: 20-30Nm, Azimuth scanning beam 40°-60° each side of centreline. Vertical guidance beam 0.9°-19° vertically. Accuracy similar to or better than ILS. Limitations:Aircraft must fit dual ILS and MLS equipment. Very expensiveAlready superseded by GPS?

Question 28

What is an INS?

Answer 28

Inertial Navigation SystemAccelerometers and gyros provide a self contained navigation system. Used in en route navigation. Requires accurate pre departure position input (susceptible to error). Loses 0.6 Nm per hour- can be improved through IRS (inertial reference system) which automatically updates position using other NAVAIDS and corrects this error. ILS/IRS systems are less accurate in the polar regions.

Question 29

What is GNSS?

Answer 29

Global Navigation Satellite SystemMultiple fixes from orbiting satellites. Range is worldwide. Accuracy- Civil

Question 30

What are Q codes and what do they mean?

Answer 30

QDR- Magnetic bearing OF aircraft FROM airfield. QDM- Magnetic track FROM aircraft TO airfield (reciprocal of QDR)QTE- True bearing OF aircraft FROM DF stationQUJ- True track required to reach the DF station. QTF- Position established by cross bearings from 2 DF sites (preferably confirmed by additional bearing from 3rd site- triangulation).

Question 31

What is a VDF?

Answer 31

VHF Direction FinderUses phase comparison of incoming signal to determine direction. Provides ATC with bearing of aircraft from VDF aerial (usually on aircraft) or track aircraft should fly to reach airfield. Operates automatically from pilots R/T transmissions. Assists radar identification and pilots navigation. Used for Instrument Approach Procedure. Accuracy: A +/- 2 degreesB +/- 5 degreesC +/- 10 degreesD >10 degrees(DRDF +/- 1 degree)Limitations:Line of sight only. Reflections dude to buildings, hangers aircraft and vehicles in the vicinity. Range only 200Nm.

Question 32

What is an FMS and how does it work?

Answer 32

Flight Management System:Can vary in complexity from basic heading and altitude hold to systems which can control the aircraft from departure to arrival. Pilot enters info on route, waypoints, aircraft weight etc into control display. FMS also gathers data from various sources including NAVAIDS and INS. Uses this info to provide inputs to flight director and autopilot. Changes can be made in flight via the Flight Director Interface. Information from all parts displayed on Guidance and Navigation Displays. Modern FMS automatically obtain navigation data from several sources- if one aid fails FMS can use data from a different source. SIDS, STARS, holding patterns etc can be flown by aircraft even if the NAVAID on which they are based is out of service.

Question 33

What is Performance Based Navigation (PBN)?

Answer 33

An ICAO concept whereby the accuracy and reliability of aircraft RNAV (Area Navigation) systems required for flight in certain air spaces, and for carrying out certain procedures such as SIDS, instrument final approaches etc are layer down as Required Navigation Performance (RNP) specifications.

Question 34

What is Required Navigational Performance (RNP)?

Answer 34

The necessary accuracy of RNAV systems. RNP 5- system must be accurate to within 5nmRNP 0.3- system must be accurate to within 0.3nm.

Question 35

What is Receiver Autonomous Integrity Monitor (RAIM)?

Answer 35

An automatic RNAV monitoring and alerting system to warn of significant system degradation. Most common is RAIM, which compares signals from all visible GNSS against the 3 or 4 being used to ascertain position in order to check and compensate for inaccuracies. RNAV system with this capability are referred to as RNP systems.

Question 36

What is an RNP Approach (RNP APCH)?

Answer 36

Specifies that if RNAV equipment meets RNP 1 and contains a RAIM (RNP?) it can be used for initial and intermediate approaches and if necessary missed approaches, but NOT final approach. If RNP equipment meets RNP 0.3 it can be used for instrument final approaches, where such procedures have been published.

Question 37

What is an RNP Authorisation Required (AR) APCH?

Answer 37

Where greater accuracy than RNP APCH required (eg significant high terrain, obstacles near approach path), only RNP systems certified to RNP 0.1 can be used to carry out these approaches.

Question 38

What are GPS Augmentation Systems?

Answer 38

In order to be sufficiently accurate for RNP operations, GPS needs accuracy and reliability enhanced by one or more augmentation systems:Satellite Based Augmentation System (SBAS):Extra SBAS satellites in geo-stationary orbit used to correct inaccuracies in GPS signals in that area of the world that owns the SBAS satellites. (USA, Europe, Japan, India- systems are compatible)Ground Based Augmentation System (GBAS):Operates similarly to SBAS, except correction signals broadcast by a ground station and cover a much smaller area. Latest GBAS systems are most accurate GNSS available- approaches using GNSS augmented by GBAS (GBAS Landing System (GLS)) currently being developed, will be accurate enough for Precision Approaches (not yet!). Aircraft Based Augmentation System (ABAS):Equipment in the aircraft checks integrity of GPS signals and adds corrections. 2 types:RAIM- Receiver Autonomous Integrity Monitor: uses signals from all visible GPS satellites to check for a correct inaccuracies contained in the signals of one or more of them. AAIM- Aircraft Autonomous Integrity Monitor: compares GPS position with position obtained from INS and/or ground based NAVAIDS such as VORs/DME/ contained in navigational database. Ground Based or Aircraft Based Augmentation System.

Question 39

What is the need for navigation in aviation?

Answer 39

How to get from A to B.

Question 40

What is Air Speed?

Answer 40

The air speed of an aircraft is the speed at which it moves through the air mass in which it flies. Air speed is measured by ascertaining the air pressure this movement exerts on the aircraft. This dynamic pressure is directly proportional to the speed of the aircraft. It can also be affected by atmospheric density- may not be as accurate at high altitudes. The performance criteria of an aeroplane is related to Indicated Air Speed (what speed to fly with flaps etc).

Question 41

What are IAS, RAS and TAS, and why are they necessary?

Answer 41

IAS- Indicated Air Speed:Air speed shown directly on the airspeed indicator. Suffers from 3 errors: Fault in instrument, badly positioned Pitot Head, density error. RAS- Rectified Air Speed:This is IAS which has been corrected for instrument and position error, available to pilot to add or subtract from IAS (usually small, 2 knots)TAS- True Air Speed:This is RAS which has been corrected for density error. At speeds in excess of 300kts the air ahead of the aircraft gets significantly compressed.

Question 42

What is Groundspeed?

Answer 42

The speed of the aircraft over the ground.

Question 43

What is a Nautical Mile?

Answer 43

The length of arc of a great circle subtended by one minute of angle measured at the centre of the earth. A knot is one nautical mile per hour. There are:6080ft in a Nautical Mile5280ft in a Statute Mile3280ft in a Kilometre.

Question 44

What is Air Position?

Answer 44

The position on the ground over which the aircraft would have been in zero wind velocity.

Question 45

What is Ground Position?

Answer 45

The position directly beneath an aircraft at a given time.

Question 46

What is the need for maps and charts and how are they accurately produce?

Answer 46

Most accurate representation of the earth= A globe. Impractical to have one of an appropriate scale on a flight deck. Method of representation of 3D shape on 2D surface= Projections. Types of Map Projections:Cylindrical Projections:Mercators Conformal Projection, Transverse Mercator Conformal Projection (used for Equatorial/Polar maps)Lamberts Conformal Conic Projection (used for Mid-latitude maps). Conformal- All angles and bearings on the earth are accurately represented. Charts:Representation of earths surface which can be overlaid with specific information not visible on surface. Purpose decides choice of information, which could include Lat and Long, Relief (elevation), divisions of airspace, danger areas etc.