M1, S1, C3 - Separation Standards

Question 1

Standard vertical or horizontal separation shall be provided between:

Answer 1

1) all flights in a Class A airspace
2) IFR flights in Class C, D and E airspace
3) IFR flights and VFR flights in a Class C airspace
4) IFR flights and SVFR flights
5) SVFR flights, except where a reduction is authorised by the CAA

Question 2

Standard separation shall be provided, in so far as possible, between…

Answer 2

…aircraft that have flight planned to operate IFR on Class F ADR airspace

Question 3

In a Class G airspace, separation between aircraft is ultimately the responsibility of…

Answer 3

…the pilot.

However, in providing a Deconfliction Service or a Procedural Service, controllers will provide information and advice aimed at achieving a defined deconfliction minima.

Question 4

Separation standards are minima and shall be increased when:

Answer 4

1) requested by the pilot
2) a controller considers it necessary
3) directed by the CAA

Question 5

In addition to the stated paragraphs, standard separation may be reduced when…

Answer 5

…authorised by the CAA and published in MATS 2.

Question 6

In the vicinity of aerodromes, the standard separation minima may be reduced if:

Answer 6

1) adequate separation can be provided by the aerodrome controller when each aircraft is continuously visible to this controller

or

2) each aircraft is continuously visible to the pilots of other aircraft concerned and the pilots report that they can maintain their own separation

or

3) when one aircraft is following another, the pilot of the succeeding aircraft reports that he has the other aircraft in sight and can maintain own separation

Question 7

Standard separation may be reduced when a SAR aircraft is…

Answer 7

…escorting an aircraft in an emergency.

A minimum is not laid down in UK FIRs and separation may be reduced to that which can be maintained visually or with airborne radar.

Question 8

If, for any reason, a controller is faced with a situation in which two or more aircraft are separated by less than the prescribed minima eg ATC errors or differences in the pilot’s estimated and actual times over reporting points, he is to:

Answer 8

1) use every means at his disposal to obtain the required minimum with the least possible delay

and

2) when considered practicable, pass traffic information if an ATS surveillance service is being provided, otherwise, pass essential traffic information.

Question 9

Reduced vertical separation may be applied during…

Answer 9

…surveillance system failure as detailed in M1, S1, C6

Question 10

Essential traffic is…

Answer 10

…traffic which is separated for any period by less than the specified standard separation.

It is normally passed in situations when ATS surveillance systems are not available.

Question 11

Essential traffic information shall include:

Answer 11

1) direction of flight of conflicting aircraft
2) type of conflicting aircraft
3) cruising level of conflicting aircraft and ETA for the reporting point, or for aircraft passing through the level of another with less than the normal separation; the ETA for the reporting point nearest to where the aircraft will cross levels
4) any alternative clearance

Question 12

Vertical separation exists when…

Answer 12

…the vertical distance between aircraft is never less than the prescribed minimum.

Question 13

The vertical separation minima are:

Answer 13

1) between aircraft flying subsonic

A) up to FL290 apply 1000ft

B) above FL290 apply 2000ft, except that between FL290 and FL410 inclusive, 1000ft may be applied between RVSM approved aircraft operating in airspace designated as being notified for the application of this separation standard.

2) between aircraft flying supersonic and between aircraft flying supersonic and aircraft flying subsonic:

A) up to FL450 apply 2000ft

B) above FL450 apply 4000ft

Question 14

In the event of a pilot advising that his aircraft is no longer capable of RVSM operations…

Answer 14

…it is particularly important that the first ATSU made aware of the failure performs the necessary co-ordination with subsequent ATSUs

Question 15

The Mode C of some military aircraft is accurate only to…

Answer 15

…the nearest 400ft during supersonic flight.

On occasions, therefore, military controllers may have to apply 4000ft separation at all levels.

Question 16

Controllers are to assess the vertical distance between aircraft by…

Answer 16

…observing the Mode C responses in accordance with the conditions for the use of Mode C specified in M1, S1, C6, or by obtaining level reports from pilots

Question 17

Aircraft may be instructed to change level at…

Answer 17

…a specified time, place or rate.

Question 18

An aircraft may be instructed to climb or descend to a level previously occupied by another aircraft provided that:

Answer 18

1) vertical separation already exists
2) the vacating aircraft is proceeding to a level that will maintain vertical separation

and

3) either…

A) the controller observes that the vacating aircraft has left the level

or

B) the pilot has reported vacating the level

Question 19

If sever turbulence is known to exist, level instructions shall be delayed until…

Answer 19

…the vacating aircraft is known to be at, or through, another level separated by the required minimum.

Question 20

Controllers shall exercise caution when instructing an aircraft to climb or descend to…

Answer 20

…a previously occupied level.

Consideration shall be given to the fa t that aircraft may climb or descend at markedly different rates and, if necessary, additional measures such as specifying a maximum or minimum climb or descent rate for each aircraft shall be applied to ensure that the required separation is maintained.

This is particularly relevant when the aircraft concerned are established in the same holding pattern.

Question 21

Pilots in direct communication with each other may, with their concurrence, be instructed to…

Answer 21

…maintain a specified vertical separation between aircraft during climb or descent.

Question 22

Controllers may authorise an aircraft to climb or descend in VMC provided:

Answer 22

1) the manoeuvre is restricted to Class D, E, F and G airspace at/below FL100
2) it is during the hours of daylight
3) the aircraft is flying in VMC
4) the pilot of the aircraft climbing or descending agrees to maintain his own separation from other aircraft and the manoeuvre is agreed by the pilot of the other aircraft

and

5) essential traffic information is given

The application of VMC climb and descent could result in TCAS RA being triggered.

Therefore, in Class D airspace when surveillance services are being provided, VMC climb and descent shall only be used where authorised and IAW any conditions specified in M2.

Question 23

The three types of horizontal separation are:

Answer 23

1) Lateral separation
2) Longitudinal separation
3) Separation based on ATS surveillance system information

Question 24

‘Level change’ means…

Answer 24

…that portion of 5e climb and descent during which the vertical separation in relation to the level of another aircraft is less than the minima.

Question 25

An ‘exact reporting point’ is a position established by a nav facility which is:

Answer 25

1) overhead a VOR
2) overhead an NDB
3) a position notified as a reporting point and which is established by the intersection of VOR radials, or of a VOR radial and a bearing from an NDB
4) a position established by a VOR radial combined with a range from a co-located or associated DME

Question 26

Lateral separation shall be applied so that…

Answer 26

…the distance between aircraft is never less than a specified amount.

It is achieved by requiring aircraft to fly on different tracks or in different geographical locations as determined by visual observations or by use of nav aids.

Question 27

Track separation…

Answer 27

M1, S1, C3.7…very complicated, never used it, not sure how it works…!

Question 28

Geographical separation must be:

Answer 28

1) indicated by position reports over different geographical locations that have been specified in MATS 2 as being separated

and

2) constant or increasing

Question 29

Longitudinal separation based on either time or distance shall be applied so that…

Answer 29

…the spacing between the estimated positions of the aircraft being separated is never less than a prescribed minima.

Question 30

Longitudinal separation is achieved by requiring aircraft to:

Answer 30

1) depart at a specified time
2) lose or gain time to arrive at a geographical location at a specified time

or

3) hold over a geographical location until a specified time

Question 31

For the purpose of application of longitudinal separation, the terms below shall have the following meanings:

Same track

Reciprocal track

Crossing track

Answer 31

Same track - when the track of one aircraft is separated from the track of the other by less than 45deg

Reciprocal track - when the track of one aircraft is separated from the reciprocal of the other by less than 45deg

Crossing track - intersecting tracks which are not classed as ‘same’ or ‘reciprocal’

Question 32

Longitudinal Separation based on time for en route…

Answer 32

M1, S1, C3.8A

Question 33

Longitudinal Separation based on distance for en route…

Answer 33

M1, S1, C3.8B

Question 34

When aircraft are being held in flight…

Answer 34

…the appropriate vertical separation shall be provided between holding and en route aircraft while such en route aircraft are within 5 minutes flying time of the holding aircraft’s flight path (or holding area where this is published), except where it is published in MATS 2 that lateral separation is deemed to exist.

Question 35

Separation between departing aircraft shall be applied so that after one aircraft takes off…

Answer 35

…the next succeeding aircraft does not take off within less than the number of minutes specified in the table below.

The minima in the table are complimentary to the en route longitudinal separations based on time.

Greater minima than that listed below may be required for wake turbulence separation purposes.

Question 36

Departure separation based on time:

Answer 36

1 minute - provided that the aircraft fly on tracks diverging by 45deg or more immediately after take off.

The minimum may be reduced when aircraft are taking off from independent diverging or parallel runways provided the procedures have been approved by the CAA

2 minutes - provided that…

…1. The preceding aircraft has filed a TAS 40kt or more faster than the following

…2. Neither aircraft is cleared to execute any manoeuvre that would decrease the 2 minute separation between them

5 minutes - provided that the preceding aircraft has filed a TAS 20kt or more faster than the following aircraft

5 minutes - provided that the 5min separation is maintained up to a reporting point within or adjacent to a CTR or terminal CTA and the aircraft will subsequently be separated either…

…vertically

…by tracks which diverge by 30deg or more
Or
…by Radar

(Only to be used at locations approved by the CAA)

10 minutes - all other scenarios

*Separation minima based on time cannot be achieved unless the whole 60seconds of each minute specified is permitted to elapse

Question 37

The minimum longitudinal separation between an en route aircraft and a departing aircraft shall be…

Answer 37

…10 minutes.

This may be reduced to 5 minutes provided that:

1) the en route aircraft has filed a TAS 20kt or more faster than the departing aircraft
2) the en route aircraft has reported over an ERP at which the departing will join the same route

and

3) the departing aircraft is given positive instructions to arrive at the same ERP 5 mins behind the en route aircraft

Question 38

In RT the term Wake turbulence shall be used to describe…

Answer 38

…the effect of the rotating air masses generated behind the wing tips of aircraft, in preference to the term wake vortex which describes the nature of the air masses.

Question 39

All aircraft including helicopters generate vortices as a consequence of…

Answer 39

…producing lift.

The heavier the aircraft and the slower it is flying, the stronger the vortex.

Vortices are especially persistent in calm conditions.

They are most hazardous to aircraft with a small wingspan during the take off, initial climb, final approach and landing phases of flight.

Question 40

Wake vortices begin to be generated by fixed wing aircraft when…

Answer 40

…the nose wheel lifts off the runway on take off and continue until the nose wheel touches down on landing.

Question 41

When helicopter weight is transferred from the landing gear to the rotor…

Answer 41

…a strong down wash is created in all directions, although this can be moved by the wind.

When helicopters are in forward flight the down wash from the main rotor(s) is transformed into a pair of trailing vortices similar to the wing tip vortices of a fixed wing aircraft.

There is some evidence that these vortices are more intense than for comparable fixed wing aircraft.

Question 42

UK wake turbulence categories are listed in…

Answer 42

…MATS 1 app B.

It should be noted that they differ from ICAO categories, which are used for flight plan purposes.

Question 43

Wake turbulence separation minima are the…

Answer 43

…spacing between aircraft, determined either by time or distance, to be applied so that aircraft do not fly through the wake of a preceding aircraft within the area of maximum vortices.

Question 44

Where the separation minima required for IFR flights are greater than the recommended separation for wake turbulence…

Answer 44

…the IFR separation minima shall be applied.

Question 45

When a flight is operating visually (ie IFR or SVFR operating under the reduced separation in the vicinity of aerodromes, VFR, or IFR making a visual approach) and is following or crossing behind another aircraft…

Answer 45

…the pilot is to be informed of the recommended wake turbulence separation minima.

Question 46

En route wake turbulence separation…

Answer 46

…no special longitudinal wake turbulence separations based on time are required.

Question 47

The following surveillance based wake turbulence separation minima shall be applied in en route flight:

Answer 47

1) minimum of 5nm between a heavy (inc A380-800) and a medium (upper and lower), small or light aircraft following or crossing behind at the same level or less than 1000ft below

Question 48

Unless alternative wake turbulence separation criteria are approved and contained in MATS 2, the following wake turbulence separation minima shall be applied in the intermediate approach segment:

Answer 48

1) 5nm between a heavy (excluding A380-800) and a medium (upper and lower) or small aircraft following or crossing behind at the same level or less than 1000ft below
2) 6nm between a heavy (excluding A380-800) and a light aircraft following or crossing behind at the same level or less than 1000ft below
3) as per final approach minima for aircraft following or crossing behind an A380-800 at the same level or less than 1000ft below

The intermediate approach phase is specific to each individual instrument approach procedure. Therefore, ATC units should define and specify in MATS 2 the area or portion of a procedure where the intermediate approach wake turbulence separation minima apply.

Question 49

Unless alternative wake turbulence separation criteria are approved and contained in MATS 2, the wake turbulence separation minima in the table below shall be applied to aircraft on final approach when:

Answer 49

1) an aircraft is operating directly behind another aircraft at the same altitude or less than 1000ft below
or
2) an aircraft is crossing behind another aircraft, at the same altitude or less than 1000ft below
or
3) both aircraft are using the same runway or parallel runways separated by less than 760m

See M1, S1, C3, P13 for table

Question 50

Wake turbulence separation minima on departure shall be applied by…

Answer 50

…measuring airborne times between successive aircraft.

Take off clearance may be issued with an allowance for the anticipated take off run on the runway; however, the airborne time interval shall reflect a difference of at least the required time separation.

Question 51

Unless alternative wake turbulence separation criteria are approved and contained in mats 2, the wake turbulence separation minima in the table below shall be applied when aircraft are using:

Answer 51

1) the same runway
or
2)parallel runways separated by less than 760m, or crossing runways if the projected flight path of the second aircraft will cross the projected flight path of the first aircraft at the same altitude or less than 1000ft below
or
3) parallel runways separated by 760m or more, if the projected flight path of the second aircraft will cross the projected flight path of the first aircraft at the same altitude or less than 1000ft below.

See M1, S1, P14 for table

Question 52

ATC shall apply the minima as prescribed above, irrespective of…

Answer 52

…any pilot request for reduced wake turbulence separation.

ATC does not have the discretion to reduce wake turbulence separation minima.

Question 53

Opposite direction departure wake turbulence:

Answer 53

A wake turbulence separation of 2 minutes shall be applied between a medium (upper and lower), small or light aircraft and a heavy aircraft, and between a medium (upper and lower) or mall aircraft and a light aircraft whenever the heavier aircraft is making a low or missed approach and the lighter aircraft is:

1) utilising an opposite direction runway for take off
or
2JR landing on the same runway in the opposite direction, or on a parallel opposite direction runway separated by less than 760m

Question 54

Displaced landing threshold wake turbulence separation:

Answer 54

If the projected flight paths are expected to cross, a wake turbulence separation of 2 minutes shall be provided between medium (upper and lower), small or light aircraft following a heavy aircraft and between a light aircraft following a medium or small aircraft when operating on a runway with a displaced threshold when:

1) a departing medium (upper and lower), small or light aircraft follow a heavy arrival or a departing light aircraft follows a medium or small arrival
or
2) an arriving medium (upper and lower), small or light aircraft follow a heavy aircraft departure, or an arriving light aircraft follows a departing medium or small aircraft.

Question 55

For wake turbulence separation purposes, aircraft carrying out a touch and go or a low approach shall be considered as…

Answer 55

…making a departure from an intermediate point on the runway.

Question 56

For wake turbulence separation purposes, helicopters air taxiing across runways shall be considered to be…

Answer 56

…a departure from that intermediate point of the runway.

Question 57

When hovering or air taxiing, a helicopter directs a forceful blast of air downwards which then rolls out in all directions.

This downwash and associated turbulence can drift a substantial distance downwind and may affect an adjacent runway or taxiway.

To minimise the effects of this turbulence controllers should:

Answer 57

1) instruct helicopters to ground taxi rather than air taxi when operating in areas where aircraft are parked or holding
2) not air-taxi helicopters close to taxiways or runways where light aircraft operations (inc light helicopter ops) are in progress. If air taxi is imperative, helicopters must be routed to:

A) avoid overflying parked aircraft, vehicles or loose ground equipment

B) follow standard taxi routes where helicopters and fixed wing aircraft share common areas on a movement area

Question 58

When a helicopter is hover taxiing or in a stationary hover controllers should avoid…

Answer 58

…taxiing light aircraft or helicopters within a minimum area comprising 3 times the rotor diameter of that helicopter.

Controllers should consider this to be a minimum distance which will need to be increased for larger helicopters.

Question 59

Caution should be exercised when a helicopter or fixed wing aircraft of lower weight turbulence category is cleared to land on a runway immediately after a…

Answer 59

…helicopter of higher weight turbulence category has taken off from that runways threshold.

Question 60

Horizontal separations based on ATS surveillance system information shall be…

Answer 60

…justified by the ANSP, approved by the CAA and detailed in MATS 2.

Question 61

Horizontal separation based on ATS surveillance system information shall not be used between…

Answer 61

…aircraft holding over the same holding point.

Question 62

Where there is a requirement for an increase in separation between aircraft prior to transfer…

Answer 62

…this shall be documented and applied IAW MATS 2.

Question 63

Where PSR information is displayed, separation must be applied using…

Answer 63

…the PSR returns.

Horizontal separation based on PSR and SSR information displayed together exists when the distance between the centres of the returns does not represent less than the prescribed minimum provided that returns do not touch or overlap.

Question 64

When approved by the CAA, separation based on radar derived information may be applied between…

Answer 64

…an aircraft taking off and a preceding departing aircraft, or other aircraft in receipt of an ATS surveillance service, provided there is reasonable assurance that the departing aircraft will be identified within 1 mile from the end of the runway and that, at the time, the required separation will exist.

Question 65

Provided the pilots are made aware of the limitations of the service, SSR may be used to provide horizontal separation in the following circumstances:

Answer 65

1) IAW MATS 2
2) to overcome temporary deficiencies within PSR cover, such as fading or clutter, the SSR return only of one aircraft may be used to provide separation from the PSR or SSR return of another aircraft provided the PSR and SSR situation displays are correctly aligned.

In this context, ‘unavailable for use due to maintenance’ does not constitute a temporary deficiency.

3) immediately after PSR failure for the minimum time necessary to establish procedural separation. Once established, services normally provided using radar may be resumed when PSR is serviceable.

Question 66

SSR shall not be used to provide horizontal separation if…

Answer 66

…a controller has any doubt about the accuracy of the position symbol due to equipment malfunction, reflections or any other reason.