Defining the Z Axis for Indoor Location

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The availability of more accurate location fixes for 911 calls, which include the Z axis is expected to increase significantly thanks to recent action by the Federal Communications Commission (FCC). On November 22, 2019, the FCC adopted rules requiring wireless carriers to deliver 9-1-1 calls with a Z-axis metric that is accurate within three meters (or approximately 10 feet) for 80% of the indoor (wireless) 9-1-1 calls.
Winbourne Consulting Defining Z-Axis

Fire fighters, medics and police officers often struggle to locate 9-1-1 callers inside multi-story and high-rise buildings unless the caller provides detailed information including a floor number, a room number, a suite number or some other relevant location information. This may lead to delays in locating and assisting the caller with their emergency. Wireless Phase II systems, which are widely deployed across the country, provide accurate X-Y coordinates to locate a 9-1-1 caller on a map. However, this location information has limited utility inside a multi-story building, especially one that has many floors. In these situations, the vertical component of the caller’s location, or Z axis, is crucial to finding the caller quickly. The Z axis, expressed as height above ground or elevation above sea level, is not currently provided with most 911 calls.

The availability of more accurate location fixes for 911 calls, which include the Z axis is expected to increase significantly thanks to recent action by the Federal Communications Commission (FCC). On November 22, 2019, the FCC adopted rules requiring wireless carriers to deliver 9-1-1 calls with a Z-axis metric that is accurate within three meters (or approximately 10 feet) for 80% of the indoor (wireless) 9-1-1 calls. Carriers must meet this requirement in the top 25% of the US markets by April 3, 2021, and in the top 50% of the US markets by April 3, 2023 (Download Rules Here). The FCC also adopted a Further Notice of Proposed Rulemaking (“Further Notice”) in which it asks if the Commission should adopt a more stringent longer term requirement and if the FCC’s rules should be changed to provide carriers with alternative options for demonstrating how they satisfy the 3 meter requirement.

The Public Safety industry has largely been supportive of the FCC’s ruling. NENA has stated: “The Z-axis metric put in place by today’s vote – the same metric agreed upon by industry and public safety – is both technically feasible and necessary for 9-1-1. These rules lay a rock-solid foundation for innovations in location accuracy, mapping, and addressing. Just as important, the questions posed by the FNPRM [Further Notice of Proposed Rule Making] are thoughtful and important; they raise critical-path issues that public safety, industry, and government will tackle collaboratively during the coming months. This extensive collaboration will be absolutely necessary to develop a comprehensive, interoperable, future-proof system for accurate, actionable, seamless three-dimensional location accuracy for 9-1-1.”

The International Association of Fire Chiefs agreed, stating that a three meter Z axis metric not only provides emergency responders with actionable location information, but it also gives the public greater assurance that when they dial 9-1-1 from their cell phones, emergency responders can find them more quickly.” It added that the Order “represents the culmination of many years of dedicated work to achieve a three meter z-axis metric.”

However, APCO does not agree, stating that “The new 911 location regulations fail the citizens of the United States. The Commission delivered a major win for wireless carriers and the one or two companies that can be used to fulfill these new regulatory requirements. The Commission had the responsibility to do the right thing for our citizens’ safety. Instead, the Commission is giving the carriers a pass, failing the American public, and leaving many issues unresolved that will ultimately cause its plan to fail. Lives will be lost as a result.” APCO had advocated that any Z-axis rules require wireless carriers to provide at least floor-level location information, and it believes that a three meter standard does not meet that requirement.

The Public Safety industry broadly agrees that there is a need for a Z-axis or elevation component to the X & Y coordinates being provided today, and they agree that the Z-axis needs to be actionable. However, there are differences of opinion on how this information should be displayed for use by first responders.

In order for the Z-axis or elevation information to have real value for Public Safety X, Y & Z coordinates must be available from the carriers and the coordinates then need to be plotted onto a building’s electronic layout or architectural drawings in order to be useful. This objective will be best achieved by the business owners, city permits departments, and the fire departments working together in order to capture all of the relevant information about a structure including elevation of each floor and sub-floor, as well as the layout of each floor and sub-floor. Having this information in an electronic format that is readily available to PSAPs is critical in making the Z-axis/elevation information actionable and useful for dispatchers, first responders and citizens.

Following are some of the issues that need to be overcome to make the Z-axis or elevation functional for PSAPs and Public Safety in general:

  • PSAPs today generally cannot take the raw Z-axis numbers in height above ellipsoid and translate them into actionable dispatchable-location information.
  • Once PSAPs obtain the ability to translate the Z-axis into a vertical location, that vertical location must then be applied to the architectural drawings of the multi-story or high-rise building in order to be useful to first responders.
  • The building’s architectural drawings or electronic building layouts must be augmented to include X, Y & Z for offices, hallways, elevators, exits, escape steps, storage/utility rooms and bath rooms, and this information must be made available to PSAPs and first responders.
  • Extensive mapping is necessary to translate Z-axis coordinates into floor levels, as floor height and numbering systems can vary—for instance, many hotels and other buildings do not have a 13th floor.
  • There are other factors that need to be considered, such as if the floor from which the 9-1-1 call came from has collapsed during a fire or earthquake, or if the electricity is out.

A unique approach to obtaining the Z-axis metric is being rolled out by NextNav, in conjunction with a $120M funding round that will accelerate its deployment of barometric and weather sensors in the top 50 markets across the US. This technology has proven to be highly accurate in delivering vertical location in tests conducted in 2018. https://urgentcomm.com/2020/01/21/nextnav-plans-to-make-vertical-location-capability-available-in-top-50-markets-this-year/ (We also reference this article in “Articles of Interest”, below.)

It will take cooperation between the private and public sector to accomplish the task of delivering the Z-axis metric nationwide, and agencies that take a proactive approach in planning for the delivery of this information into their PSAPs will be better prepared to improve first responder’s ability to find callers in multi-level and high-rise buildings/structures. This information is also one of the cornerstones for the Smart City initiatives being contemplated by cities around the country and the world, as they seek to improve the safety and emergency response services in densely populated areas. Winbourne Consulting has extensive experience in all areas of location information, smart city initiatives and how to implement technologies that improve response time to incidents. For additional information, contact Winbourne Consulting at info@w-llc.com.

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