Section 16. Severe Weather Avoidance Plan (SWAP)


SWAPs are formalized programs that are of considerable value in areas that are particularly susceptible to severe weather. SWAP statements are prepared by ARTCC TMUs and provide specific details surrounding a particular weather event. The ARTCC TMUs consider applicable alternatives that may be used to mitigate expected airspace impacts. These include CDRs, playbook routes, FEA/FCAs, capping/tunneling, AFPs, and any other TMIs that are being considered. The SWAP statement is then delivered to the ATCSCC for discussion and coordination and may be sent as a SWAP advisory. SWAP advisories are sent by the ATCSCC and developed from SWAP statements and provide direction to customers and facilities on what TMIs are expected to be used to manage airspace constraints.

Plans that are properly developed, coordinated, and implemented can reduce coordination and TM restrictions associated with rerouting aircraft around areas of severe weather, resulting in better utilization of available airspace.

  1. Air traffic facilities must:
  1. Favor and accept traffic flows that are not normally routed through their area.
  2. Monitor, evaluate, and adjust programs to ensure maximum effectiveness.
  3. Use the following procedures when considering a route unusable:
  1. Notify the ATCSCC anytime airspace, established flows of traffic, routes or any other factor affecting airborne capacity becomes or is expected to become unusable. The ATCSCC must be notified when normal traffic can be accepted.
  2. Enter into the NTML, using the “SWAP” tab, any information regarding unusable routes and/or routes that become available.
  3. Solicit flights to file and/or fly routes that are impacted by weather, when appropriate.
  4. Issue minute-in-trail/mile-in-trail restrictions that allow airspace to remain available when defined as “severely constrained.” A severely constrained area is identified as an airway, fix, or sector impacted by any circumstance that significantly reduces, but does not eliminate the ability to handle aircraft.


This minimum flow of traffic will ensure that demand does not exceed current capacity, yet will assist in determining the suitability for increased traffic for the impacted route or area.

  1. Increase and reduce TMIs as necessary to accommodate airspace impacts.
  2. Record in NTML two or more aircraft identifications:
  1. When flights deviate significantly, and/or elect not to file or fly on a route impacted by weather.
  2. When flights elect not to depart and/or land due to the current weather conditions.
  3. Forward flight information to the ATCSCC.
  1. Facilities may consider issuing a SWAP statement indicating all expected impacts to available routes and airspace in their area of concern. The SWAP statement should contain mitigation strategies for expected impacts. This includes alternate routes, use of CDRs, use of TMIs, altitude capping/tunneling, possible FEAs/FCAs, AFPs, etc.
  1. The ATCSCC must:
  1. Obtain a severe weather analysis from weather information providers and discuss the findings with the appropriate TMU.
  2. Conference affected facilities and customers to apprise them of forecast severe weather conditions and the routes or areas that will be impacted.
  3. Formulate a dynamic severe weather operational plan. Coordinate TMIs and alternate routes with all affected facilities.
  4. Use, to the extent possible, the following options in the order listed when developing an operational plan:
  1. Expanded miles-in-trail initiatives.
  2. SWAP advisories.


When developing the SWAP advisory, the ATCSCC should consider all possible mandatory and recommended route options; applicable CDRs and playbooks; and the use of User Preferred Trajectory (UPT) and Integrated Collaborative Routing (ICR) strategies.

  1. Reroutes.
  2. Ground delay programs.
  3. AFPs.
  4. Ground Stops.
  1. Transmit advisories describing the existing or forecast weather conditions, the operational plan, alternate routes, or cancellation thereof.
  2. Be the final approving authority for traffic flows and reroutes.
  1. The ARTCC TMU must:
  1. Coordinate with the ATCSCC when implementing SWAP procedures that affect other ARTCCs. If possible, this coordination should be completed at least 2 hours prior to expected implementation.
  2. When suitable, facilities should consider developing a SWAP statement that specifies expected airspace impacts; developed shared FEAs representing airspace impacts; possible route closures; effective times of constraints; and expected routing alternatives including applicable CDRs and playbook routes.
  3. Notify affected facilities within their area of responsibility when SWAP is expected to be implemented, including initiatives, reroutes, and affected times.
  4. Furnish the sector or facility issuing the revised clearance a route of flight to a point where the new route connects with the filed route.
  5. Notify the ATCSCC and affected facilities within their area of responsibility when normal routings can be resumed.