MOBILE, Ala.- While the convenience of Global Positioning System (GPS) can assist drivers to desired locations, pilots can also depend on it to locate runways that have been renamed as the result of shifting magnetic fields, thus assuring passengers’ safety.
Working for the U.S. Army Engineer Research and Development Center, inventor Theodore “Teddy” Lee used his expertise as a former Army Air Traffic Controller to create methods of “Predicting the Future Magnetic Alignment of a Runway.” He received his invention patent in September 2022 as an emergency operations specialist in Mobile, Alabama, for the Office of Research and Technology Transfer (ORTT) U.S. Army Corps of Engineers Reachback Operations Center (UROC).
“Airport runways are named by their magnetic orientations. As the magnetic field changes over time, so must runway names,” Lee said. “Renaming a runway is expensive and requires a lot of planning. Because passenger safety is the most important part of air travel, when a runway needs to be renamed, doing it quickly is part of that safety.”
According to National Oceanic and Atmospheric Administration’s (NOAA) National Center for Environmental Information, the Earth’s magnetic field is constantly changing. While large-scale changes, such as a complete reversal of the magnetic field, happen over several thousand years, smaller changes over shorter periods affect aviation and other navigation. This shifting magnetic field affects airports and airline operations and causes runway names to change.
The World Magnetic Model (WMM) is a data-based, mathematical representation of Earth’s large-scale magnetic field. It’s critical to virtually every smartphone map application and serves as the standard navigation tool for the Federal Aviation Administration (FAA.)
How GPS works
Lee explained that GPS determines movement using four essential information points: direction of travel (orientation), location (latitude and longitude), precise time data and velocity (speed).
“To get this critical information, GPS uses an internal compass for orientation; satellites for accurate time and location; data receivers to retrieve data from the satellites; and algorithms for data synchronization,” Lee said. “One of the most important of these algorithms is the WMM.”
Working with ERDC’s Geotechnical and Structures Laboratory, he collaborated with senior research scientist Dr. Mihan McKenna Taylor to develop improvements that can be used to augment the WMM when it exceeds accuracy requirements.
“The WMM is used by the Department of Defense and other agencies to calculate and predict the anticipated slow-moving changes of the geomagnetic field over five-year periods for airport runways navigation and orientation,” Lee said. “I noticed many runway renames occurring simultaneously. Our novel invention offers efficient accounting of unanticipated changes (so-called geomagnetic jerks) in the magnetic field over time.”
“The safety of air travel is vitally important, and in February 2018, and NOAA, the organization responsible for producing the WMM, made a public announcement that the 2015 WMM was inaccurate almost two years ahead of schedule,” Lee said. “The WMM mathematically models these changes over five-year periods (e.g., 2015 – 2020).”
As a former Army Infantryman and geospatial analyst, Lee said he also has a personal interest in the accuracy of directional maps.
“Infantrymen still navigate using topographic line maps (TLMs) and compasses; air traffic controllers still use TLMs for Search and Rescue (SAR) missions, along with GPS for runway names and navigation aids; and geospatial analysts use magnetic north to create TLMs,” Lee explained. “To this day, the bottom of all military TLMs have a magnetic declination diagram, and production date. If the production date is before the latest WMM five-year update, then the Soldier using that map may have inaccurate measurements and could end up in the wrong place.”
“Pilots have compasses in their cockpits for orientation,” Lee added. “In recent years, the number of runway incursions have increased, and these are often recorded as pilot error, when in many cases the error could be attributed to inaccurate agreements between a runway name and a magnetic compass heading.”
A New Discovery
Lee shared that the inaccuracy of the 2015 WMM ahead of schedule meant that something inside the Earth’s outer core was causing the field to change faster than expected.
“I wanted to know if there were a way I could understand why the field was moving in the directions that it was moving. Upon investigating, I noticed something I could neither explain, nor find information about in current literature,” Lee said. “I hypothesized that it was a hidden magnetic axis that has been somehow overlooked in modeling efforts. I started comparing renamed runways with changes in data from airfield surveys. I wanted to know if changes in airfield surveys were related to this overlooked axis, and it appeared that it did!”
Lee then experimented with different ways to pull meaningful data from what he was observing. He discovered that if he drew one line from the runway center to the current hidden axis location and another line from the runway centerline to the forecasted axis location, the angle between the two points was nearly identical to WMM changes in magnetic declination.
“But even more surprising, this method also appears to account for at least some of the unexpected changes in the field (like the one that caused the 2015 WMM to be inaccurate),” Lee said.
Like the WMM, this invention can potentially be used by the FAA for future runway rename planning, as well as any system that currently uses GPS for location and navigation. However, unlike the WMM, which takes at least a year to gather measurements and data, this method can be used for specific locations after a single measurement and one simple calculation.
Lee will be honored at a plaque patent presentation ceremony in 2023 by leaders at ORTT, which processes patents for ERDC.
For additional technical information, visit the patent application link:
US Patent for Predicting the future magnetic alignment of a runway Patent (Patent # 11,454,737 issued September 27, 2022) - Justia Patents Search