The FCC on Friday voted to advance rules that would require wireless carriers to provide more precise vertical-location data from 911 calls made on cellphones inside multi-story buildings, in an effort to help emergency call centers better identify which floor the caller is on.

“Although we may be accustomed to Uber or Waze using our smartphone’s location sensors to optimize their services automatically, less is done with height data,” Commissioner Brendan Carr said in a statement. “And yet knowing on what floor an emergency is occurring can mean the difference between life and death.”

The Commission proposed the vertical (or ‘z-axis’) location data must be accurate within 3 meters of the handset for 80 percent of indoor 911 wireless calls, tentatively concluding that the metric is sufficient to identify a caller’s floor level most of the time. The effort would start in major metropolitan areas and the rulemaking suggests it could be accomplished in the nation’s 50 largest cities by 2023. The FCC will now seek public comment.

Industry group CTIA, on behalf of the four nationwide carriers, proposed a 5 meter requirement pending more tests related to performance and scalability. However, the public safety community did not agree, and CTIA later revised its recommendation to align with the 3 meter (or 10 feet) metric, while stressing the importance of further testing.

Commissioners Geoffrey Starks and Jessica Rosenworcel both took issue with the 10 foot requirement in that it didn’t go far enough. Starks said that while the 3-meter metric will get first responders close, it still leaves a margin of error that can send them to the floor above or below a person in need. He concurred in part because the proposed rules don’t set out a plan to increase accuracy to greater than 3 meters.

“Only floor level accuracy will give first responders the right tools to go to the right floor, the first time, every time,” Starks said in his statement. “We need a plan to get there and that plan has to get it done as quickly as possible.”

Commissioner Rosenworcel in her dissenting statement said the proposed timeline is not ambitious enough, and the lack of floor-level accuracy falls short of what first responders need.

“The fact is we need real precision if we want to be able to locate with floor-level accuracy every 911 call—and we need it fast,” Rosenworcel said. “And on this score this rulemaking misses the mark.”