FCC Proposes Mobile Phone E911 Vertical Location Accuracy Standard

At its March 15 Open Meeting, the FCC intends to vote on a Fourth Further Notice of Proposed Rulemaking (“FNPRM”) in its Wireless E911 Location Accuracy Requirements proceeding that would consider adoption of a vertical, or z-axis, location accuracy metric. Currently there is no z-axis metric, despite proposals by the Commission going back to as early as 2014. The FNPRM, if adopted, would propose a z-axis metric of +/- 3 meters relative to the handset for 80 percent of wireless E911 calls, the same metric proposed in a Third Further Notice in the proceeding. The Commission deferred promulgation of a specific metric for lack of sufficient test data in a 2015 order that established benchmarks and timetables for the deployment of z-axis in the top 50 Cellular Market Areas (“CMAs”).

The FCC now appears ready to tentatively conclude that +/- 3 meters for 80 percent of calls is the appropriate standard to allow first responders to better locate people calling 911 from mobile devices in multi-story buildings. The proposed obligations would begin for the four nationwide mobile carriers on April 3, 2021, in the top 25 markets (i.e., CCMAs) and a year later for other mobile carriers. The proposed transition beyond the top 25 CMAs extends another two years, until April 3, 2023, for CMAs 26-50, for the nationwide carriers, and through April 3, 2024, for other carriers in those markets.

On behalf of the four nationwide mobile carriers, CTIA had submitted z-axis testing conducted with two vendors – NextNav LLC and Polaris Wireless, Inc. – and proposed a +/- 5 meter location accuracy standard for 80 percent of fixes from mobile devices. The vendors both used barometric sensor data from mobile handsets to establish location. CTIA had also called for additional testing, which might validate a more accurate metric, but NextNav and Polaris themselves supported a +/- 3 meter metric. In addition, the 5 meter metric was unanimously opposed by public safety entities as too imprecise because first responders could have to contend with a range of up to 2 floors both above and below the actual location of the mobile device. In December, CTIA and the four nationwide mobile carriers continued to call for more testing, but essentially accepted the inevitability that a +/- 3 meter standard would be proposed by the FCC.

The draft FNPRM also would seek comment on the 80 percent standard. The current rules mandate, in each CMA where z-axis technology is used nationwide, CMRS providers must deploy z-axis technology to cover 80 percent of the CMA population. However, the draft FNPRM proposes the accuracy standard for 80 percent of wireless E911 calls within the affected CMA. The draft FNPRM asks whether the metric should apply to 80 percent of all wireless calls (seeming to imply from all devices), or as CTIA proposed, only for calls from mobile devices capable of delivering barometric pressure sensor-based altitude estimates. Further, the draft FNPRM concludes that nearly all smartphones in the market are equipped with barometric pressure sensors, but cites only to information about iPhone 6 and later models and the Samsung Galaxy smartphones, which have had barometers since 2011. However, the draft FNPRM asks whether the requirements should only apply to devices manufactured after a date certain, which would help address the continued use of older and refurbished phones without sufficient barometric accuracy.

The draft FNPRM also would seek comment on other technologies that can help to accurately locate wireless 911 callers. If the FNPRM is adopted, comments will be due 45 days after it is published in the Federal Register and reply comments will be due 75 days after publication.