‘Interval Management’ Technology Set To Make Its Real-World Introduction


Real-world operational trials of so-called Interval Management (IM) procedures are set to begin with flights into and out of Dallas Fort Worth International Airport (DFW). The FAA has partnered with American Airlines over the past few years to certify and install ADS-B In avionics on AA’s fleet of Airbus A321 single-aisle airliners. The trials involve Albuquerque airspace and will continue for one year to gather data.

IM technology uses GPS precision coupled with Automatic Dependent Surveillance-Broadcast (ADS-B) receiver-transmitters to reduce the in-trail separation intervals for enroute aircraft as well as those on approach to busy airports. Similar to GPS-enabled Reduced Vertical Separation Minimums (RVSM), which for years have allowed aircraft to fly within tolerances as close as 1,000 feet vertically (compared with 2,000-foot separations before precise onboard navigation reporting), IM procedures will enable more aircraft to access airspace and airports in less time, increasing efficiency, reducing fuel burn, and thus reducing carbon emissions.

The FAA has been offering guidance on the technology through a series of animated storyboards. Heavy with acronyms and initializations, the presentations show how precise data from ADS-B is shared by not only controllers, but also by flight crews to enable closer separation intervals. Trailing aircraft are presented with target speeds that they can use to ensure the required separation. Rather than air traffic control guessing where incoming traffic will end up at approach points, the technology enables better control of spacing, without the need for speeding up or slowing down that increases fuel burn.

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Mark Phelps is a senior editor at AVweb. He is an instrument rated private pilot and former owner of a Grumman American AA1B and a V-tail Bonanza.

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  1. RVSM has nothing to do with GPS. It is a system based purely on barometric altimeters. The FAA does use ADS-B Out signals to collect statistical data on fleet-wide altitude-keeping performance in the flight levels, but that data collection isn’t what keeps the planes apart, and also the positional data comes from non-compliant GPS receivers (non-WAAS) as long as the airlines are operating under the exemption the FAA gave them. (Look up exemption 12555 that extends through 2025.)

  2. Not a single mention of wake turbulence. WT kills, as has been proven several times. The air carriers and FAA have continued to try to pack 10 pounds into a 5 pound bag for years. The answer is more runways, which no one wants to address.

    • Or, a better tax system than the outdated one we now have. More runways might help, but there’s still limited airspace to get to the same airport.

      Some economists need to look at airport resources. In the meantime, there needs to be some sort of moratorium on changing existing airport land to other uses. It sounds drastic, but it’s not nearly as drastic as mowing down parts of a city to put in a new one.

      The airlines are currently incentivized to suck up all the gates they can, and push out all the flights they can because those resources are not being properly priced by municipal airports. The runways and nearby airspace is a practical tragedy of the commons situation, and the gate game is just pernicious.

      I’m not informed enough to really know, but from the outside, it seems to me the citizens of a city would be better off charging per gate use and not letting the airlines lease a gate.

    • More runways is a short term fix. More runways make it a six pound bag and they’ll be trying to stuff 12 pounds in it long term.

      Similarly more highways don’t reduce traffic. They get stuffed in the long run as well.

  3. HOW are pilots going to be presented with target speeds that work with different types and weights of aircraft? Not an insurmountable problem, but as a retired Tower and TRACON controller – just wondering. I used to fly IFR into ORD a lot, in Mooneys and Comanches, and tell the controller I could hold 140 kts once I started down the glideslope, holding that speed until short final, meaning almost over the threshhold, courtesy of long runways. I never heard back if they believed me or not.