During severe weather season, air traffic that is deviating (or has been rerouted) for thunderstorm avoidance, may cause complexity and volume issues in numerous ZMP sectors requiring TMU to implement various Capping and Tunneling TMIs (Traffic Management Initiatives). This Capping and Tunneling Plan describes the coordination necessary to accomplish these initiatives successfully. For this plan “Capping” refers to stopping departure aircraft at-or-below FL230 until a point in space beyond the constrained high altitude sector(s). Beyond that point these capped flights can safely be climbed to their requested altitude. For this plan “Tunneling” refers to the practice of stopping MSP departures at 10,000 or 11,000 ft. due to conflicts occurring with deviating MSP arrivals in close proximity to the MSP Approach Control airspace.

During a large thunderstorm event rerouted flights may cause volume issues in numerous ZMP high altitude sectors. One mitigation strategy to relieve pressure on these impacted sectors is to cap departures from the Minneapolis Terminal area at or below FL230. During a SWAP event ZMP TMU will work with the Area supervisors to identify and coordinate the need to cap MSP departures. Since flying longer distances at lower altitudes burns more fuel, coordination with the aircraft operators should be accomplished prior to implementing the Capping Plan so that extra fuel can be flight planned for each departure. We should also ask the dispatchers to remind the pilots to not ask for higher during these capping events. Then, thorough coordination needs to be accomplished between MSP Tower/TRACON and each affected ZMP sector. TMU will also need to coordinate with adjacent ARTCCs if the flights will remain capped until a point inside their airspace.

This capping procedure encompasses all 12 departure routes out of MSP and is not dependent on a specific runway configuration at Minneapolis.

Expect the capped altitudes to be AOB FL230 eastbound and AOB FL220 westbound. The routes and distances will need to be determined dynamically for each weather/red sector scenario.

This capping procedure may add significant volume and complexity to our low altitude sectors that provide airport control at many airports, therefore additional TMIs (i.e. miles-in-trail) may be needed to manage the additional volume in those sectors.

ZMP impact depends on the specific Area and high altitude sectors that are experiencing volume issues due to severe weather reroutes. Several of our sectors to the northwest of MSP encompass all altitudes - from the ground up - therefore additional mile-in-trail (MIT) restrictions may need to be implemented to mitigate volume concerns.

Also, many of our northern tier sectors are very large, so the point-in-space where the capped departures are allowed to climb higher may be several hundred miles away, possibly extending into adjacent facilities’ airspace. Pre-coordination with our neighboring ARTCCs (ZLC, ZDV, CZY, ZOB & ZAU) may be required if this occurs.

In certain scenarios, ZMP may also need to cap departures from adjacent facilities climbing into our congested airspace.

Occasionally we experience thunderstorm events around the MSP terminal airspace that are so complex that we cannot laterally de-conflict MSP arrival aircraft, that are deviating as they descend, with MSP departures that are also deviating as they climb out. Tunneling refers to the practice of stopping departures at 10,000 or 11,000 ft. until their route is clear of head-on arrivals that have been stopped in their descent at 11,000 or 12,000 ft. This usually occurs within the confines of the initial ZMP departure sector and the decision to climb the departures is made at the discretion of the sector controller. In order for a Tunneling TMI to be successful, thorough coordination needs to be accomplished between both ZMP and MSP Tower/TRACON TMUs, and all affected sectors.

In addition to the coordination described above, all plans to cap or tunnel should also be briefed at our ZMP stand-up weather briefings, and on all ATCSCC planning telcons.