Simultaneous Operations on Intersecting Runways

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Simultaneous Operations on Intersecting Runways

35TH ANNUAL CONFERENCE, Tunis, Tunisia, 15-19 April 1996

WP No. 88

Simultaneous Operations on Intersecting Runways


At the last conference in Jerusalem current IFATCA policy on the matter of “Simultaneous Operations on Intersecting Runways” adopted at the 1988 conference and reading as follows:

“Where procedures are developed to allow simultaneous operations on intersecting runways, these procedures must take into account ATC workload, the number and effects of any restrictive procedures and the possible need for improved radar systems”


Was extended with the adopted recommendation B2:

“ The introduction of Simultaneous IFR Operations on Intersecting / Converging Runways should only take place when:

  1. The ATC facilities involved have the appropriate equipment, staffing levels and training;
  2. The appropriate risk analysis should be carried out involving pilots and controllers, which should include simulation and real-time trials utilising data from the local airport and operators intending to operate with these procedures;
  3. Until world-wide standards have been established, the introduction of local or regional operations should be restricted to local operators by Letters of Agreement;
  4. That specific procedures are introduced that will ensure that the approach sequence to each runway can be managed in such a way that each aircraft will be able to continue its approach, landing and possible missed approach safely”


ICAO EUR is still studying SIMOPS in the Aerodrome Operations Group (AOPG) and is preparing Regional provisions on this matter.

The ECAC states have produced a ECAC APATSI manual on Mature ATC procedures. In Chapter 1.4 the concept of SIMOPS (Simultaneous Operations on Intersecting/Converging Runways) is described.

The intention of this paper is to review further aspects of SIRO as studied by ICAO and APATSI, and review comments of MA’s where SIRO are already implemented.

SIRO have been used and are still being used by a number of states to gain airport capacity. From state to state these procedures differ as far as the conditions concerned under which these operations are allowed, in particular concerning the naming of the procedure, phraseology (the read back of the conditional landing clearance), signs, markings, lights, information about the procedure to pilots, weather conditions, limitations to aircraft types or operators, declared Reduced Landing Distance Available (RLDA), description of the Hold Short Position, the buffer zone between the Hold Short Line on the runway with the RLDA and the other runway, radio frequencies being used, conditional landing – clearance, alternative missed approaches.

As long as SIRO procedures are being discussed, the level of dependency or independency has been the central point of the discussion (independently in the meaning of totally uncoordinated). It has always been SC 1’s opinion that procedures which manage the crossing point of two intersecting runways are dependent, as in the event of any unexpected occurrence the associated risks of the aircraft involved can never be mutually exclusive.

It has been recognised by AOPG/10, based on American experience presented in an information paper to that meeting, that “the worse the weather is the greater dependency should be. In other words, under IMC a high level of dependency should be maintained, while greater independency could be allowed under VMC.”

Based on this recognition the strategy of AOPG has been changed from dividing provisions related to dependency to dividing provisions related to meteorological conditions, and AOPG already started working on the provisions for SIRO in VMC operations (there is also more experience with SIRO in VMC). The VMC limits : ceiling is not less than 1000ft and visibility is not less than 5km.

If this means that SIRO under VMC are independent, then this will result in additional workload and responsibility for ATC as well as for pilots. Pilots will have some (extra) conditions (restrictions??) when performing SIRO in VMC. ATC must calculate and avoid the risk of collision by giving clear instructions. In case of a missed approach the reduced separation minima rule (Doc.4444 Part IV para 1) may be applied, but when the cloud base is at 1000’ and the aircraft is climbing out of 1000ft during the missed approach, the controller has no longer visual contact. Besides the execution of ATC instructions to aircraft during a missed approach are dependent on pilot performance / reaction time, which is also dependent on what kind of system he is flying (automated, coupled, manual) and if he is able to perform climbing or descending turns during a missed approach. Should this be an “avoiding action” instruction ( also in the phraseology).

Deviation alerts, position predictions and other automated devices could help the controller in assessing the possible risks during SIRO.

Another discussion point is the question, must all the traffic for the two runways work on one and the same frequency with the argument to increase the pilots situational awareness during SIRO? A result can be frequency congestion and blocked communications in the event of an “avoiding action” instruction.


ICAO EUR (AOPG) has changed strategy regarding SIRO. They no longer divide between dependent and independent operations but between VMC and IMC operations.

Provisions for SIRO during VMC operations are being developed by ICAO EUR. The next step will be the provisions for SIRO in IMC.

SC1’s opinion is still that all SIRO are dependent, and that ATC should have the facilities to ensure that the prescribed safeguards can be achieved.

The safety of SIRO requires appropriate training and increased vigilance as well on the part of controllers and pilots.

That during SIRO in VMC the responsibilities of controllers and pilots should be clearly defined.

That Missed Approach Procedures should guarantee the appropriate separation between aircraft.

It is recommended that:

Where aircraft are operating in the vicinity of the aerodrome, with less than the required IFR separation, the aircraft involved and any potential conflict point, must be visible to the aerodrome controller.

Last Update: February 12, 2020  

February 12, 2020   52   Jean-Francois Lepage    1996    

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