FCC Seeks Comment on Wireless E911 Z Axis R&O and FNPRM

On Monday, November 25, 2019, the Commission released the Fifth Report and Order and Fifth Further Notice of Proposed Rulemaking (“R&O” and “FNPRM”) in the Wireless E911 Location Accuracy Requirements proceeding, which was adopted in the November Open Meeting (PS Docket No. 07-114). The R&O adopts a vertical location accuracy metric, or “z-axis”, for wireless E911 calls of plus or minus 3 meters and geographic requirements for the top Cellular Market Areas (“CMAs”). The FNPRM proposes and seeks comment on additional measures to improve E911 location accuracy, including long-term timelines and demonstration requirements.

The adopted R&O and FNPRM included several clarifications and additions from the previously circulated draft item. Specifically, the adopted item clarifies its definition of “z-axis capable” devices and adds additional context from the record to support the adopted 3-meter metric. The R&O also requires that, where available, providers must provide floor level information with their associated confidence and uncertainty data and live call data reporting. The adopted R&O additionally expands the privacy and security provisions regarding 911 call information, requiring CMRS providers to certify that neither they nor any third parties or vendors they rely on are using or storing data for non-911 purposes, and adds that 911 data may be used for non-911 data purposes with prior express consent. The FNPRM seeks additional comment on the feasibility of a 2-meter metric, floor level reporting for emergency communications, dispatchable location data, and other approaches to z-axis deployment.

Report and Order

  • 3-Meter Metric – The R&O finds that the 3-meter metric is technically feasible in the near term and adopts the proposed implementation timelines of April 3, 2021 for the top 25 CMA markets and April 3, 2023 for the top 50 CMA markets, as proposed in the March 2019 Fourth FNPRM. The Commission relies on test data as determined by NextNav and Polaris in the Stage Z test bed.
  • Deployment – The R&O adopts the proposal to apply the 3-meter accuracy metric to 80% of wireless E911 calls, consistent with the approach to E911 horizontal accuracy. The 3-meter metric will apply to all handsets that support vertical location capabilities, not just new handsets or barometric pressure sensor capable handsets.
    • The R&O clarifies that a device will be considered “z-axis capable” as long as it can “measure and report” vertical location without a hardware upgrade, rather than just “support” location, as published in the draft item. The R&O explains that this “makes clear that any device technically capable of measuring and reporting vertical location information without a change in hardware must be enabled to do so – and actions by carriers, device manufacturers, operating system providers, chipmakers, or z-axis vendors that would prohibit technically capable devices from actually and effectively measuring and reporting z-axis information put the public and emergency personnel at unacceptable risk.” (¶ 25). The R&O rejects suggestions to exclude old handsets from these rules and declines to limit capable devices to barometric pressure sensor devices.
    • The adopted R&O adds that it believes CMRS providers are capable of negotiating requirements with third parties to timely deploy z-axis solutions, and that the flexible, technology-neutral approach adopted in the item will remove uncertainty and give carriers greater leeway to negotiate with competing vendors and existing solutions. (¶ 30).
  • Reporting Z-Axis Location Information – The R&O requires Commercial Mobile Radio Service (“CMRS”) providers to report z-axis information as Height Above Ellipsoid (“HAE”).
    • The Commission recognizes the general consensus for using HAE as the baseline measurement, but also that current vertical location technology does not support floor level identification. CMRS providers are not required to report floor level data where it is not technically feasible to do so, and in such cases should deliver z-axis information in HAE. However, in cases where carriers have reliable information about the caller’s floor level, they should provide it.
    • The R&O does not require providers to translate from HAE to other formats. The Commission concludes that translation mechanisms can be developed using HAE as a baseline reference, and for the time being, affords industry and public safety the flexibility to develop cost-effective solutions on both sides.
  • Confidence and Uncertainty (“C/U”) Data – The R&O applies a 90% confidence and uncertainty requirement to z-axis data, as applied to horizontal data. CMRS providers will be required to provide vertical confidence and uncertainty data on a per call basis to requesting PSAPs with a 90% confidence level, i.e., they must identify the range above and below the estimated z-axis position within which there is a 90% probability of finding the caller’s true vertical location.
    • The R&O adds that where available to the CMRS provider, floor level information must be provided with associated C/U data in addition to z-axis location information. (This is a change from the draft language, which did not include such a requirement) (¶ 41).
  • Compliance Certification and Call Data Reporting – The R&O adopts the proposal to require nationwide CMRS providers to certify for the April 2021 and April 2023 compliance deadlines that z-axis technology is deployed consistent with the manner in which it was tested in the test bed. The R&O does not require proof of performance testing.
    • Additionally, the R&O expands the live call data reporting rules to include z- axis data, and where available, floor level information (¶ 47). The live call data reporting rules require CMRS providers to file quarterly reports of their aggregate live 911 call use of each location technology in four geographic morphologies within six representative cities (Test Cities). Non-nationwide CMRS providers must report aggregate live 911 call data collected in one or more of the Test Cities or the largest county in their footprint.
    • The Commission clarifies that live call data relating to the use of live call and floor level technologies will be used solely for informational purposes, not compliance purposes. (¶ 48).
  • Z-Axis Privacy and Security – The R&O amends the FCC’s rules to require that CMRS providers and the vendors they rely on for z-axis information may only use 911 call z-axis information for 911 purposes, except as required by law or with prior express consent.
    • The adopted R&O also adds additional details regarding the CMRS certification requirement to ensure compliance with data protection. Specifically, the adopted R&O requires CMRS providers to certify that neither they nor any third party they rely on to obtain z-axis information for 911 purposes will use that information for any non-911 purpose, except with prior express consent or as required by law. This extends the certification requirement included in the draft item which only required CMRS providers to certify their compliance. The adopted R&O now requires that CMRS providers certify that both they and their vendors (i.e., device manufacturers and third-party location technology vendors) are using or storing 911 data properly. The adopted R&O also adds that CMRS providers and vendors are permitted to use 911 call information for non- 911 purposes if given prior express consent to do so, in addition to where required by law.
    • The R&O clarifies that it does not intend for this certification to be used to prevent or impede vendors from having access to z-axis information for valid purposes like system calibration and accuracy verification (¶ 50).
    • Any 911-related z-axis or floor level information that is stored before or after the call should be subject to the same privacy and security protections that apply to NEAD data. Accordingly, if a CMRS provider intends to store such data for 911 location purposes, it should file an addendum to ensure that the protections outlined in the NEAD plan will cover the provider’s location transactions end-to-end. For non-stored data, CPNI requirements continue to apply and prohibit unauthorized use of the data.
  • Comparison of Benefits and Costs – The Commission addresses the costs and benefits of adopting the 3-meter metric, and reaffirms its decision that implementing the metric accounts for a large share of the total annual benefit floor, estimated at $97 billion, along with additional incalculable benefits. This number only calculates the value of statistical lives saved and the R&O expects there will be many additional benefits from this metric implementation.


The Commission seeks comment on whether to establish a long-term timeline for migrating to a more stringent z-axis metric than 3 meters, and ultimately whether to require CMRS providers to deliver floor level information with wireless indoor 911 calls. It also proposes to amend the rules to expand on the current options for demonstrating z-axis or dispatchable location deployment.

  • Continuing to Improve the Z-Axis Metric – The FNPRM seeks comment on additional steps to facilitate the long-term location accuracy objectives. Specifically, the FNPRM seeks comment on the feasibility of phasing in more granular z-axis requirements over time, specifically a 2 meter metric, and any adoption timeframes, other alternatives the Commission should consider for a narrower vertical location accuracy metric, and whether enhancements are needed to improve the vertical location accuracy testing process.
    • The FNPRM seeks comment on efforts to convert z-axis data to precise floor level information, and on any mechanisms or resources that are available to convert this information, as well as any potential timelines for incorporating floor level accuracy. The Commission also asks whether to require confidence and uncertainty data with floor level information, and associated costs and benefits with a floor level requirement.
    • The FNPRM seeks comment on the feasibility of ensuring emergency personnel have access to floor level information in the future, and makes providing floor level location a priority. The adopted FNRPM encourages commenters to assess the reliability of their proposed technological solutions to providing floor or unit number data in foreseeable emergency communications (i.e., Wi-Fi, Bluetooth) and how it should affect any future changes to location data requirements. Specifically, it seeks comment on Google’s proposal that the Commission include an option that allows carriers to provide floor level estimates instead of HAE-based 3-meter z-axis measurements. (¶ 67-68).
  • Alternative Options for Z-Axis Deployment – The FNPRM seeks comment on whether expanding options beyond the population-based 80% CMA coverage requirement serves the public interest. Specifically, the FNPRM seeks comment on how CMRS providers would measure and document their deployment in urban and dense urban morphologies, and on how an established option for CMRS providers to deploy z-axis capable handsets nationwide as a means of z-axis compliance would impact deployment and costs. The Commission also seeks comment on a top 50 and possible nationwide deployment of z-axis technology location accuracy standard, and seeks comment on how to reduce infrastructure and compliance costs while providing needed z-axis coverage. The adopted FNPRM seeks additional comment on whether the Commission should consider international initiatives in developing z-axis solutions.
  • Dispatchable Location and Alternatives to the NEAD – The FNPRM proposes and seeks comment on allowing CMRS providers to demonstrate dispatchable location deployment by means other than NEAD reference points, how to account for uncertainty in dispatchable location data, and the associated costs and benefits as well as privacy and security safeguards associated with this proposal. The FNPRM also seeks comment on dispatchable location alternatives, for example, requiring reporting of both dispatchable location and z-axis, along with other access points or connection locations.

The rule amendments included in the Report and Order will be effective 60 days from publication in the Federal Register, with the exception of rules requiring OMB approval, which will be effective at a later date. Sections requiring OMB approval include Sections 9.10(i)(2)(ii)(C) and (D), (i)(4)(v), and 9.10(j)(4) which establish the compliance dates and HAE reporting requirements for CMRS providers, the z-axis use certification, and the confidence and uncertainty data requirements.

On January 16, 2020, the Commission published the Fifth Report and Order and Further Notice of Proposed Rulemaking in the Federal Register therefore establishing the following effective date and comment dates:

The R&O is effective March 16, 2020. As noted in the Federal Register, compliance will not be required for Sections 9.10(i)(2)(ii)(C) and (D) (April 2021 and April 2023 3-meter metric benchmark compliance deadlines), (i)(4)(v) (required z-axis use certification), (j)(4) (providing confidence and uncertainty data, and where available, floor level information) until the Commission publishes a document in the Federal Register announcing the compliance date.

Comments on the FNRPM are due February 18, 2020.

Reply comments are due March 16, 2020.

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