There are lots of reasons why a person calling 911 might not be able to tell operators which floor they're on in a high-rise building. They could be panicked, injured, ill, incapacitated or simply confused. Yet precious minutes are wasted when emergency personnel have to search a building to find a person in need. With a new app called Sensory, emergency responders soon may be able to use a caller's smartphone to locate their exact position in a building.

Columbia University researchers William Falcon and Henning Schulzrinne created Sensory using a two-step process. First, the pair utilized all existing cellphone features that help narrow down a caller's location. All iPhones manufactured after 2014 already include GPS, altimeters and barometers that can be combined with information about signal strength to help emergency responders determine if a person is outdoors or inside a building. But when it comes to tall buildings, just knowing a person's altitude may not help because the distance between floors varies from one building to the next.

An answer for first responders

So Falcon and Schulzrinne analyzed the plans of more than 1,000 buildings in New York City to figure out the average distance between floors in residential buildings and office buildings. The pair tested their app in 63 experiments in five high-rises — including Rockefeller Center — and found that it could pinpoint a caller's location within two floors with about a 91 percent accuracy.

"The research was motivated by the countless victims who can’t get help in time because of how long it can take responders to search a building," Falcon said in an interview with MNN.

In a 2014 survey conducted by Find Me 911, a coalition of first responders that includes the U.S. First Responders Association and the American Academy of Emergency Medicine, dispatchers said that they regularly receive calls from people in need who often can't share or don't know their location. They sometimes accidentally give the wrong address or floor number. Some callers are too young to know and/or share their address. Some speak a different language than the call center operator. Others are suffering from a stroke, dementia or another condition that hinders their speech. Some are afraid. Dispatchers also received calls from those who are deaf or hard of hearing and are unable to hear the operator's questions.

The new Sensory app could help shave precious minutes off the time it takes first responders to get to those calling for help. It's not perfect. But it's a start. And it could make the difference between life and death for those calling 911.