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Reduced runway separation (RRS)

Reduced runway separation is not a mandatory part of S1 training.

Requirements

ATCOs can only use Reduced Runway Separation if the following aspects are fulfilled:

  • The tailwind component on the ground must not exceed 5 knots

  • Ground visibility must be equal to or greater than 5 kilometers

  • The main cloud base must be at 1000ft AGL or higher

  • Wake turbulence separation must be maintained at all times

  • The braking effect on the runway must not be significantly impaired by precipitation

    • On Vatsim, the braking effect is considered to be significantly impaired by precipitation: snow (SN), snow grains (SG), ice grains (PL), hail (GR) and rime (GS) - in other words, all precipitation except rain (RA) and drizzle (DZ)

  • The following aircraft in the RRS sequence must receive traffic information about the preceding traffic

Aircraft categories

For the Reduced Runway Separation procedure, aircraft have been divided into three categories.

These three categories are:

CAT 1 CAT 2 CAT 3
Single-engine propeller-driven aircraft with a maximum take-off weight of up to 2 tons.

Single-engine propeller-driven aircraft with a maximum take-off weight greater than 2 tons but less than 7 tons.

Twin-engine propeller-driven aircraft with a maximum take-off weight of less than 7 tons.

 All other aircraft
ATD_RRS_LFZ_KAT1.png ATD_RRS_LFZ_KAT2.png ATD_RRS_LFZ_KAT3.png

The following registrations apply in Germany:

  • D-E

  • D-K

  • D-M

The following registrations apply in Germany:

  • D-C (up to 7 tons)
  • D-F
  • D-G
  • D-I

The following registrations apply in Germany:

  • D-C (over 7 tons)
  • D-B
  • D-A

Examples: C152, C172, P28A, A210, DA40, DR40, DV20, SR22

Examples: DA62, PA34, TBM9, BE58, B350

Examples: AT75, DH8D, C25C, CRJ9, B738, A359

Possible constellations

There are four different possible constellations of these categories on a runway. We will now look at these step by step with a focus on Reduced Runway Separation.

Departure behind departure
  • The following departure receives traffic information about the leading departure.
  • If all other criteria are met, the second departure may be cleared for take-off as soon as the first departure has taken off and is a defined distance away from the second departure. The distance is specified by the LFZ-KATs (aircraft categories):

Preceeding
 Suceeding
 Requirement
CAT 1 / CAT 2
 CAT 1
 airborne and at a distance of 600m
CAT 1 / CAT 2
 CAT 2
 airborne and at a distance of 1500m
CAT 3
 all
 airborne and at a distance of 2400m

  • As soon as the second departure has taken off, any applicable separation must exist.

  • Example of application: First departure is a DV20 IFR, second departure a BE58 VFR. No separation must be established between the two aircraft in D(CTR), only wake turbulence separation, as the VFR is a departure. However, since light behind light does not require wake turbulence separation, I only have to consider the runway separation. Without Reduced Runway Separation, I would have to hold back the take-off clearance until the DV20 has flown over the end of the runway. Using RRS, I can now clear the following take-off as soon as the DV20 has taken off and is 1500 m away from the BE58. This means I can use the runway more effectively and have more capacity.

Arrival behind arrival

  • The second approach receives traffic information about the approach ahead.

  • If all other criteria are met, the second approach may be cleared for landing as soon as the first approach has landed and is a defined distance away from the threshold. Additionally, the first approach must continue moving and leave the runway without backtracking. Because the landing clearance is explicitly clearance to overfly the runway threshold, it must of course be issued before the threshold is crossed. If the criteria are not (yet) fulfilled, a missed approach must be instructed. The distance is specified by the LFZ-KATs (aircraft categories):

Preceeding
 Suceeding
 Clearance before
 Requirement
CAT 1 / CAT 2
 CAT 1
 aircraft crosses runway threshold
 vacating runway and at least 600m from threshold
CAT 1 / CAT 2
 CAT 2
 vacating runway and at least 1500m from threshold
CAT 3
 all
 vacating runway and at least 2400m from threshold

This situation may seem somewhat strange, as a landing clearance is issued even though there is another pilot still on the runway. However, if the distances are maintained, this is actually legal and is practiced in reality.

Arrival behind departure

  • The approach receives traffic information about departure.

  • If all other criteria are met, the approach may receive landing clearance as soon as the departure has taken off and is a defined distance away from the threshold. Because the landing clearance is explicitly clearance to overfly the runway threshold, it must of course be issued before the threshold is crossed. If the criteria are not (yet) fulfilled, a missed approach must be instructed. The distance is specified by the LFZ-KATs (aircraft categories):

Preceeding
 Suceeding
 Clearance before
 Requirement
CAT 1 / CAT 2
 CAT 1

aircraft crosses runway threshold


 airborne and at least 600m from threshold
CAT 1 / CAT 2
 CAT 2
 airborne and at least 1500m from threshold
CAT 3
 all
 airborne and at least 2400m from threshold
Departure behind arrival

Reduced runway separation may not be used in this constellation.

Phraseology examples

German English
G: VERKEHR C172 FLIEGT *VON PISTE 25* AB G: TRAFFIC C172 DEPARTING *ON RUNWAY 25*
G: VERKEHR A320 IST *AUF PISTE 25* GELANDET G: TRAFFIC A320 LANDED *ON RUNWAY 25*
G: VERKEHR PA34 LANDET *AUF PISTE 25* G: TRAFFIC PA34 LANDING *ON RUNWAY 25*

Miscellaneous and example

Example of the procedure
We issue a take-off clearance, the next approach is on a 3NM final. In this situation full runway separation is not so likely, so we give traffic information to the landing traffic about the departing traffic. As soon as this is done and the meteorological conditions are suitable, we can apply RRS. The traffic info can read: “DLH414, TRAFFIC A320 DEPARTING RUNWAY 26R”. Theoretically, the traffic information can also be given when the aircraft is cleared to land. However, as RRS is quite tight, it is advisable to give the traffic information as early as possible so you only have the landing clearance left to give and can keep it brief and concise later. As soon as the departing traffic has taken off and passed the prescribed distance from the runway threshold, the landing clearance can be given: “DLH414 WIND 170 DEGREES 6 KNOTS RUNWAY 26R CLEARED TO LAND”.
Marker in the sector file
Of course, you do not have to estimate the distances in meters. Depending on the runway direction selected in Euroscope, you will find green markers on the runway (design may vary depending on the FIR). These describe the distances for the various combinations of aircraft CATs from the start of the runway. The first marker is at 600m and the following ones at 1500m and 2400m. The picture shows an example of these markings for runway 08L in Munich. The representation may differ depending on the FIR.

ATD_RRS Marker.png
Article about Reduced Runway Separation

Anyone interested in the topic of RRS beyond the content mentioned above will find an interesting article on the subject in an issue of “Flugleiter”, the magazine of the air traffic controllers’ union. It can be found from page 48 onwards.
Flugleiter 04/22

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