Human Factors and Technicalities in a Multi-Sector Planner Environment

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Human Factors and Technicalities in a Multi-Sector Planner Environment

54TH ANNUAL CONFERENCE, Sofia, Bulgaria, 20-24 April 2015

WP No. 154

Human Factors and Technicalities in a Multi-Sector Planner Environment

Presented by PLC


This paper aims to present the factors which need to be taken into account when introducing MSP as a manning scenario.


1.1. The idea of a multi-sector planner is not new. In certain units this kind of arrangement has been used for a long time, while other providers have a desire to implement it.

Countries where MSP is known to be used:

  • Netherlands (ACC, all sectors)
  • United Kingdom (London TMA)

1.2. The MSP scenario has caused a lot of dispute. While some claim that it has many benefits, others argue that it has even more drawbacks.

1.3. IFATCA strongly supports 4EP (Four Eyes Principle) as the ideal manning scenario. However, IFATCA has recognised the need to look deeper into the human factors and potential hazards in case of introducing MSP.

1.4. The technical requirements for MSP operations will also be discussed.


At the Gran Canaria conference in 2014 the following definition of MSP was adopted:

MSP: situations where two or more executive controllers working different sectors are assisted by another appropriately qualified controller. The assisting controller is required to be qualified to assist the executive controllers.


The MSP concept was proposed as a means of workload management. The role of an MSP planner is to offer medium term strategic rather than tactical solutions to manage traffic complexity. With the aircraft trajectories planned over multiple sectors, the sector controllers’ workload can be reduced and traffic flow improved.

2.1. The benefits of MSP

2.1.1. Workload

MSP is a good method of keeping the controller’s workload between certain limits. For instance, with high traffic, executive controllers can split two sectors, using one planner for the overview. The option of combining sectors gives the opportunity to maintain the controller’s workload at an acceptable level.

2.1.2. Airspace

In particular when two or more sectors are leading to a single merge point (e.g. stack), a controller planning for multiple sectors is an ideal way to keep the overview of the traffic and minimise unnecessary coordination between planners. For instance, this has proven to be effective in the Netherlands. Also, a planner in charge of multiple sectors has the opportunity to distribute the oncoming traffic more evenly throughout the sectors, thus improving the traffic flow and balancing the workload of the executive controllers.

2.1.3. Staffing management

MSP is a working method that enables ANSPs to be flexible with their staff.

During peaks, the multi-sector planner provides a good overview across multiple sectors. Of course, it is necessary to mention that the planner may only work on sectors for which they hold a valid rating.

When traffic is low, it is possible to combine sectors and/or positions so fewer controllers are needed on them, allowing more opportunity for taking breaks. There is greater flexibility in deploying personnel. However, this is not necessarily only a benefit on MSP. Other, non-MSP environments follow the same rostering logic.

2.2. Potential hazards when working MSP

2.2.1. High workload and loss of safety net

During periods of higher workload or traffic bursts, if the multi-sector planner is very busy, the executive controller(s) may have to carry out certain planner tasks which could distract them from performing their core function of separating aircraft, which could lead to reducing safety. The planner may find it very difficult to keep a detailed traffic picture for multiple sectors, and frequency monitoring is significantly less likely to occur. This is a safety hazard and therefore it should be possible to add an extra planner and thus provide a 4EP environment. Furthermore, executive controllers who participated in certain simulations reported that they generally did not feel comfortable losing their designated planner controller, which would be the case with busy MSP environments.

Furthermore, if an emergency situation occurs on one sector, the multi-sector planner becomes more involved in that situation, thus leaving the other executive controller(s) practically without a planner. There should always be a technical and rostering possibility to add an extra planner, which would again ensure 4EP.

2.2.2. Communication

Coordination between the multi-sector planner and the executive controllers in an MSP environment can become quite complex when it comes to prioritisation. If the MSP decides to intervene in some way, are there rules for coordination with multiple sectors? In The Netherlands there are no special procedures or rules for such coordination and it is a matter of priorities in a given moment. However, in those states where MSP is a new concept, coordination among three or more people might be confusing and overwhelming and it might take some time for controllers to adjust.

Furthermore, in a 4EP environment, the planner and the executive controller monitor, analyse and separate the same traffic. In an MSP environment, there is the risk of the planner discussing a situation or issuing a clearance/instruction to the ‘’wrong’’ executive controller, and this could (especially during high complexity/traffic) cause confusion and potentially lead to unsafe situations.

2.3. The technical requirements for MSP

Technology supporting air traffic management is fast evolving. Today there is digital data communication among controllers, and between controllers and aircraft; there is improved position accuracy for flight operations, better conflict prediction, and improved sector complexity assessment. However, there are no clear technical requirements for MSP. Still, there are some specific technical requirements to be met as a prerequisite for multi-sector planning arrangements.

2.3.1. Opening and closing of sectors

In addition to the standard options to combine or split sectors between teams each comprising two controllers (4EP), supervisors need to have the technical possibility to set a combination of three (or more) controllers. The combining and splitting of sectors should be intuitive and not time-consuming, especially as it might be necessary in time-critical situations (e.g. an emergency). Also, important information regarding traffic entered in the system before the combining/splitting must be preserved (not erased or otherwise lost or hidden in the system) during the process. Seating arrangement in an MSP environment needs to be modified to accommodate one planner and multiple executive controllers in an efficient manner.

2.3.2. Support tools

Considering the vast technological differences among various ANSPs, it is difficult to generalise about the mandatory equipment to be used, be it in an MSP environment or any other scenario. However, in many ANSPs there are various tools at controllers’ disposal: Trajectory Prediction (TP), Medium Term Conflict Detection (MTCD), Flight Path Monitoring (FPM), to name a few. All these tools help in decision-making and reducing the workload of the planner.

The EUROCONTROL PHARE (The Programme for Harmonised ATM Research in EUROCONTROL) programme developed several tools in the late 1990s to aid controllers in a multi-sector planner role. In a series of simulations ran at that time, the main graphical functions were Tactical Load Smoother and Look-Ahead Display. Tactical Load Smoother (TLS)

The Tactical Load Smoother is a PHARE Advanced Tool developed to calculate and identify traffic complexity. Its purpose is to analyse future traffic up to 40 minutes in advance, taking into account a number of parameters including prediction uncertainty, and to indicate when and where conditions are likely to become excessively difficult for sector controllers. It offers various displays, such as Traffic Load Graph, Problem Load Graph, Complexity Map. For each of these indicators, a threshold level can be set. Look-Ahead Display (LAD)

The LAD displays a standard radar picture forward in time with future conflicts, and permits interaction with aircraft trajectories through modification of the aircraft Flight Leg.

2.3.3. Adjusted HMI

The MSP environment requires certain modifications and details in the HMI setting.

Various tools enable detection of areas of conflicting traffic. The Tactical Load Smoother mentioned above offers colour-coding (yellow/red) for areas of high demand on the controller. Aircraft trajectories should also be coloured differently on demand (flight leg embellishment) to indicate whether or not there is conflicting or potentially conflicting traffic for the inspected flight.

MSP screen congestion could become a problem, for several reasons. First of all, the number of aircraft under control might be greater, since one planner is responsible for traffic on two or more sectors. Secondly, in case the labels on the MSP screen have more fields, the increased label size might lead to label-overlapping and cause label text problems. Furthermore, various tools which could be used for multi-sector planning, such as Trajectory Support Tool, Sector Load Window and so on, could mean additional windows on the planner’s screen(s) if opened often/permanently on screen. All this might become a hindrance to the multi-sector planner’s work.

Various filtering options need to be at planner’s disposal to easily filter out unconcerned labels in various situations. It is preferable that these various options be automated, to reduce the risk of errors.

All these factors must be taken into account if and when introducing the multi-sector planner scenario.

2.4. The human and procedural requirements for MSP

2.4.1. Training

Generally speaking, an MSP environment should not require more tools, procedures and airspace knowledge.

Where MSP is deployed, controllers must hold a valid license for multiple sectors. For example, in Amsterdam ACC, all area controllers are current in all five ACC sectors for both the planner and executive role. However, this may not always be feasible, especially in centres with many sectors.

2.4.2 Airspace

Airspace design and sectorisation should be taken into account when assessing the possible introduction of MSP. A more direct route structure will spread traffic out, producing a different traffic environment where congestion areas are not fixed, but variable. An optimal route environment will optimise flights, which will in turn reduce the workload of the multi-sector planner.

In an environment where multiple sectors lead to one merge point and/or where it is needed to start sequencing aircraft already in an ACC environment, one planner for multiple sectors may be beneficial due to better traffic overview and reduced coordination requirements.


The MSP concept was proposed as a means of workload management. In certain countries it has been successfully applied for years. Others strongly oppose it. On one hand, the introduction of MSP might require a lot of technical support through various tools; the seating arrangement needs to be modified and HMI adjusted; communications among controllers can become complex and ambiguous; sectorisation and airspace might need to be adjusted. Conversely, if introduced properly in appropriate areas, MSP could be a successful tool for workload and staffing management; it is a good method of keeping the workload between certain limits and in certain cases an ideal way to keep the overview of the traffic. All these factors, especially the human aspect, need to be evaluated if and when an ANSP decides to implement MSP. IFATCA still strongly supports the use of the 4EP principle.


It is recommended that this paper be accepted as information material.


Last Update: October 1, 2020  

May 14, 2020   608   Jean-Francois Lepage    2015    

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