Traffic Flow Management (TFM)

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Collaborative Trajectory Options Program (CTOP)

Updated March 13, 2014


One of the primary causes for congestion and delays in the National Airspace System (NAS) is that the number of flights (demand) often exceeds the ability of the airspace to accommodate the traffic (capacity). The effort to balance demand with capacity is known as Traffic Flow Management (TFM).

Many times, the reason that demand exceeds capacity is a constraint of some kind. The constraint can be due to weather, an airspace restriction (such as a TFR), or an overloaded air traffic control sector. As a result, the FAA has created a number of tools, known as Traffic Management Initiatives (TMIs), to help work around these constraints to manage demand and avoid congestion. These TMIs include:

  • Coded Departure Routes (CDRs)
  • National Playbook Routes
  • Flow Evaluation Areas (FEAs) / Flow Constrained Areas (FCAs)
  • Airspace Flow Programs (AFPs)

However, these tools are not always sufficient to handle issues that arise.

Several years ago, the FAA tasked its Collaborative Decision Making (CDM) Future Concepts Team (FCT) with starting work on a new type of program to assist in the TFM effort, allowing for more input from aircraft operators in the way that constraints are handled. Initially, the new program was known as System Enhancements for Versatile Electronic Negotiation (SEVEN).

This new program is now known as the Collaborative Trajectory Options Program (CTOP) and has been absorbed by the larger Collaborative Airspace Constraint Resolution (CACR) effort. CTOP has completed final testing and is being deployed in March of 2014. NBAA has been an active participant on both the FCT and on the TFM Deployment Team since the inception of the program.

The CTOP Concept

Basically, CTOP is a TMI that automatically assigns delay and/or reroutes around one or more FCA-based airspace constraints in order to balance demand with available capacity.

The benefits of a CTOP are two-fold:

  1. Air traffic managers can create an airspace boundary and control any air traffic that crosses that boundary. This is similar to what is done now with AFPs. However, CTOP has the ability to handle multiple Flow Constrained Areas (FCAs) within a single program, allowing different parts of the program to be adjusted independently as conditions change. It also automatically assigns delays or reroutes to flights in order to dynamically manage the demand as conditions change. For example, as conditions improve, CTOP can automatically adjust and reroute traffic off of lengthy reroutes and back onto their original routes, reducing their delays.
  2. A CTOP is collaborative in that it allows operators to submit, well in advance of the issuance of the program, a set of desired reroute options (called a Trajectory Options Set or TOS) that can be used to route around an FCA or constraint. In other words, operators can accept a reroute, from a list of routes that they have submitted to ATC, instead of simply taking a ground delay or being subject to a reroute that FAA dictates.

A TOS can contain as many route options as desired and will give the operator the ability to rank their specified routes in preferred order by “weighting” each route with a relative cost number. In other words, the system will automatically assign the lowest “cost” route that is available from the list of routes submitted in the TOS.

How CTOP Will Affect Operators

An operator’s level of involvement with a CTOP event is largely dependent upon how much planning they wish to do and how complex their operation is. In order to realize the benefits of CTOP, an operator will need to be willing to do a bit more advance planning, particularly on days when constraints are expected – such as on convective weather days.


First, there is the option to not participate fully in CTOP initiatives. In these cases, operators may file only their flight plan, meaning that the route which is filed in the flight plan will serve as a “single-option” TOS.

For operators who choose to do this, the chances of receiving a ground delay are much higher since, if their filed route becomes unavailable, there are no other options to choose from and they will have to accept the ground delay. Once informed of their delay, the operator could take further steps by submitting subsequent TOS messages in an effort to reduce or eliminate this delay.


To participate with CTOP, operators will need to submit a set of route options – their TOS – along with their flight plan, in advance of the flight. While the mechanisms to allow operators to do this are still being developed, operators will likely have several options.

A number of popular flight plan service providers are working on enhancements to their systems that will allow them to assist operators in creating TOSs, submitting them to ATC, and keeping those operators updated on changes.

What this will look like to the operator will depend on the service that they use. However, it is anticipated that most will offer some form of customer-facing web interface, which will ask operators for some basic preferences information and then handle much of the TOS submission/monitoring process automatically.

Operators should contact their flight plan service providers to determine what level of service will be offered.

Once the TOS has been submitted, the operator needs to be prepared to receive updates from ATC as conditions change. While one particular route might be assigned initially, that route assignment could change several times before departure. This is due to the fact the CTOP is constantly evaluating the constraint(s) and making adjustments to maximize capacity.

It is important to note that the operator must be willing and prepared to accept any of the routes contained in their TOS.

The main difference between the current system and what CTOP offers is the ability for the operator to provide multiple route options in advance for a given flight without having to negotiate last minute with ATC on an amended route when their original filed route is not available. The intent is to provide the operators with more control over their desired trajectory instead of having to rely on the FAA to make route adjustments.

Latest News

FAA's New CTOP Initiative Aims to Reduce Airspace Congestion
December 13, 2012
In 2013, the Federal Aviation Administration (FAA) is slated to implement a new traffic management initiative known as the Collaborative Trajectory Options Program (CTOP), which will better balance demand with available capacity. Under a CTOP initiative, operators submit alternative routes of their choice around or away from a constraint, thus providing additional options for air traffic controllers to expedite flights away from congested airspace. Flights that have submitted a trajectory option set (TOS) could be exempt from ground delays or in-flight reroutes associated with such constraints. Read more about CTOP.

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