ATC

Question 1

What do NATS do

Answer 1

NATS are not only for the day to day responsibilities they are planning and developing the infrastructure behind ait traffic control.

Question 2

NATS has been a part-privatised company since 2001 with ownership divided across several
stakeholders, who are they?

Answer 2

49% is owned by the government,
42% is owned by thew airline group
5% is owned by employees
4% HAL Limited

Question 3

What are the two Flight infomation regions called over the UK

Answer 3

London and Scottish

Question 4

What is London FIR

Answer 4

London Flight infomation region is controlled in the swanwick centre which was made in 2002. They cover the majority of England Wales. This holds the London controlled airspaces called, London Terminal Control and London Area control.

Question 5

What is London Terminal Control

Answer 5

London terminal control Is one of the busiest airspaces in Europe. It covers any aircraft below 24,500 Ft which are inbound or outbound flights to London Airports. This control zone spreads south to the French boarder, East to Netherlands Border, Noth to just below Birmingham and west to Bristol.

Question 6

What is London Area Control

Answer 6

London area Control is for any en route aircraft that crosses into its Flight information region. This is for England and Wales up to the scottish boarder.

Question 7

Military Control

Answer 7

Military Air Traffic Control provide services to civil and military aircraft
operating outside controlled airspace. They work closely with civilian controllers to ensure safe
co-ordination of traffic.

Question 8

Scottish area control centre

Answer 8

They cover aircraft from 2500 Ft up to 66,000 feet. The airspace is Scotland, Northern Ireland,
Northern England, the Midlands, North Wales and the North Sea

Question 9

Oceanic Area Control Centre

Answer 9

controls the airspace over the eastern half of the
North Atlantic from the Azores (45 degrees north) to a boundary with Iceland (61 degrees north)

Question 10

Where is Scottish Control

Answer 10

They are located in Prestwick and they control the whole of Scotland and Northern Irland

Question 11

Air Traffic Control Officers (ATCOs) are responsible for?

Answer 11

the safe, orderly and efficient movement of
aircraft, from the moment it leaves the departure gate to the moment the aircraft arrives at it’s
destination gate.

Question 12

Whether controllers are working in a Control Tower or an Area Centre the role will incorporate one
or more of the following responsibilities

Answer 12

Preventing collisions between aircraft in the air.
* Assisting in preventing collisions between aircraft moving on the apron and the
manoeuvring area.
* Assisting in preventing collisions between aircraft and obstructions on the manoeuvring
area.
* Expediting and maintaining an orderly flow of air traffic. of air traffic.

Question 13

Controllers are provided with details of flights that will pass through their airspaces or arrive /depart aerodromes in that vicinity, what information do controllers receive?

Answer 13

The callsign, route, altitude and speed of the intended flight are, amongst other details displayed on
an electronic or paper flight progress strip which is generated by the ATC computers when a flight
plan is filed.

Question 14

What Frequency radios do we use?

Answer 14

ATc contact pilots with VHF radios except over the Atlantic where thye use high frequency. Also, communicaitons sent by ATC have to be read back by pilots,

Question 15

What must controllers do when flights leave their airspace

Answer 15

It is important that controllers pass infomation of flights to the secotr they are going into next so the controllers are aware. This is normally done via computer link.

This rule also applies if the next sector is one inside an adjacent centre’s airspace. The UK must coordinate with Air Traffic Control Centres in Dublin, Shannon, Brest, Paris, Brussels, Maastricht and
Copenhagen. Likewise these adjacent centres must inform the UK about flights approaching UK
airspace.

Question 16

Class A airspace

Answer 16

only Instrument Flight Rules (IFR) flight is permitted. It is the most
strictly regulated airspace where pilots must comply with ATC instructions at all times.
Aircraft are separated from all other traffic and the users of this airspace are mainly major
airlines and business jets.

Question 17

Class C Airspace

Answer 17

airspace in the UK extends from FL195 to FL660. Both IFR and Visual Flight Rules
(VFR) traffic operates and requires a clearance to enter the airspace and compliance with
ATC instructions are mandatory.

Question 18

Class D Airspace

Answer 18

airspace is for IFR and VFR use; an ATC clearance is needed and compliance with
ATC instructions is mandatory. Control areas around aerodromes are class D and in class D
airspace, a speed limit of 250 knots applies if the aircraft is below FL100.

Question 19

Class E Airspace

Answer 19

is for IFR and VFR use. IFR traffic requires an ATC clearance is needed and
compliance with ATC instructions is mandatory for separation purposes. VFR traffic does
not require a clearance to enter class E airspace.

Question 20

What size are airways

Answer 20

Airways are normally 10 miles wide and have bases between 5,000 feet and
7,000 feet and they extend upward to a height of 24,500 feet (FL245).

Question 21

Upper Air routes size

Answer 21

Their vertical limits are usually Flight Level FL250-FL
460. Civil and military aircraft operating above FL245 are subject to a full and mandatory Air Traffic
Control Service

Question 22

Class G Airspace

Answer 22

aircraft may fly when and where they like, subject to a set of simple rules.
Although there is no legal requirement to do so, many pilots notify Air Traffic Control of their
presence and intentions and they take full responsibility for their own safety, although they can ask
for help.

Question 23

What services can pilots get in uncontrolled airspace

Answer 23

Deconfliction Service
* Traffic Service
* Basic Service

This can give some degree of protection but the pilots are in charge of their own safty

Question 24

what is an Alerting Service

Answer 24

provided to notify appropriate organisations regarding
aircraft in need of search and rescue aid, and assist such organisations as required.

Question 25

what is a A Procedural
Service

Answer 25

is a non radar-based service in which deconfliction advice is provided against other aircraft
receiving a Procedural Service from the same controller.

Question 26

Oceanic crossing, whats the distance planes have to maintain.

Answer 26

IN RVSM airspace aircraft can be separated 1000 ft Vertically.

60 Nautical miles distance left and right

10 Min between the aircraft on the same track and at the same level.

Question 27

London terminal Control Separation Requirements

Answer 27

Aircraft have to be 3 Nautical miles if they are at the same level or 1000 ft vertically

Question 28

Outside the London Terminal control area,

Answer 28

aircraft operating under radar control must be kept 5
nautical miles apart if they are at the same level or 1000ft vertically up to FL290.

Above this, 1000ft vertical separation may continue to be provided up to FL410, subject to aircraft being suitably equipped to comply with Reduced Vertical Separation Minima (RVSM) rules, other wise 2000ft
should be applied

Question 29

Reduced Vertical Separation Minima (RVSM)

Answer 29

Aircraft that have had their altimeters checked to a high degree of accuracy and which can comply with other strict criteria are allowed to fly across the Atlantic track structure with only 1000 feet separation
above FL290 and below FL 410. This separation standard allows many more aircraft to fly through
airspace where RVSM is allowed

Question 30

Medium Term Conflict Detection (MTCD)

Answer 30

MTCD aims to reduce the controllers’ workload by equipping them with a tool that aids them with
decision making. The tool uses a variety of data inputs to predict where an aircraft will be up to 20
minutes in the future, based on the aircraft’s level, speed and heading/ route. If the controller inputs
any tactical instructions the system is updated. Controllers can also enter a “what- if” instruction,
this allows a controller to check what may happen without yet committing to the decision. This
“what-if” trajectory is displayed on the radar screen so that the controller can visualise the new
information.

Question 31

Time Based Separation (TBS)

Answer 31

This changes the way aircraft are separated - instead of distance it takes into consideration the wind and wether and The stronger the wind, the quicker the wake vortex that is produced will be dispersed. As the wind
speed increases, aircraft can be positioned closer together in sequence on final approach, therefore
increasing the available landing rate.

Question 32

Primary Radar

Answer 32

This gives the controllers a very basic images - this is where the aircraft is in correlation to where the radar is and then high terrain points.

Question 33

Secondary Radar,

Answer 33

Before an aircraft departs from an airfield or before it enters the airways systems it is
allocated an individual four-digit code, which the pilot dials up in the transponder (this is called Mode
A). When the aircraft gets airborne, or before it enters the airways systems, the ground based radar
interrogates the transponder. When it recognises the code, which is allocated to that particular flight,
the aircraft’s height information (this is called Mode C) and callsign, is displayed to the Controller in
the form of a label next to the position of the aircraft.

Question 34

Mode S radar,

Answer 34

Mode S is a development to supersede the present Mode A and C technology and the limitations
that this system has. At present the radars interrogate the transponders of aircraft and receive the
information about the aircraft and its height. In areas of high traffic density, for example in the holds
around Heathrow, the integrity of the mode A and C is sometimes adversely affected by the
garbling of all the radar returns. Mode S alleviates these shortcomings because the radar system
will, in effect, target individual aircraft rather than trying to attempt to resolve all the replies.
Mode S provides the controller with the opportunity to view certain information, e.g. Selected Flight
level/Indicated Air Speed/heading etc., which the pilots have set in the cockpit to aid with
conformance monitoring and reducing communications between controllers and pilots.

Question 35

Conformance monitoring

Answer 35

The use of electronic data to record ATC instructions given by the controller, combined with the
radar information, allows the ATC systems to monitor an aircraft’s conformance with instructions.
Such systems track the actions of the aircraft compared to those expected from the ATC
instructions and if there is a discrepancy between the two, the system provides the controller with
an alert that can be checked and if necessary acted upon.

Question 36

Navigation what types are there

Answer 36

The most accurate of the ground based navigational aids is the VHF Omni-directional Range (VOR)
which emits radial signals which aircraft can fly along. There are 360 radials, which an aircraft could
fly toward or away from a VOR. Each radial represents 1 degree from 0-359 degrees.

VOR’s often have an associated DME (Distance Measuring Equipment) with them. This shows the
pilot how far the aircraft is away from the VOR.

Due to their accuracy, VORs can also be used for establishing holds. Heathrow’s 4 inner holds are
established overhead VORs.
A Non-Directional Beacon (NDB) just emits a signal which the pilot navigates toward. The range of
most NDBs is in the region of about 25 nautical miles whereas a VOR has a much greater range in
the order of 125 nautical miles.

The ILS is a ground-based radio guidance system, which transmits two directional
radio beams, the localiser and the glide path. The pilot then receives indications in the cockpit
advising if the aircraft needs to fly up/down or left/right to keep on the correct approach path.
The usual descent path for an ILS is 3 degrees.