A location gap inside a building usually means a dementia GPS tracker cannot get a clear satellite signal. A broad or delayed pin may be a fallback estimate, not proof of the person's exact room, floor, or exit route. No tracker is perfectly accurate, and some devices work poorly indoors, according to the Alzheimer's Association's technology safety guidance. Families should treat tracking as one part of a wider safety plan.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- Why GPS becomes unreliable indoors
- Why accuracy varies between buildings
- How caregivers should read a location gap
- Build protection beyond the tracker
- What to do when the person is missing
Why GPS becomes unreliable indoors
GPS calculates location using signals from visible satellites. Walls, roofs, tall buildings, and other obstacles can block the required line of sight. When satellite signals disappear, some devices estimate location through Wi-Fi or cellular networks.
Apple explains that its devices use these alternatives until GPS satellites become visible again in its location-services guidance. That switch can produce a pin covering a general area rather than a precise spot. It may also make the person appear stationary, outside the building, or at a nearby address. Such a pin does not reliably show which room or floor the person occupies.
Why accuracy varies between buildings
Indoor performance is not uniformly poor. A 2010 Aarhus University study measured errors below five meters in tested wooden buildings and below ten meters in most tested brick and concrete buildings. Phone GPS was less available and accurate than advanced receivers. Results changed with building materials, surrounding structures, the number of walls, overhead stories, satellite geometry, and reflected signals.
These reflections—called "multipath"—reach the receiver by indirect routes and can distort its calculation. The Aarhus University indoor GPS study shows why performance in one home cannot predict performance in a hospital, apartment block, or shopping center. A tracker may therefore work near a window or entrance but lose precision deeper inside the same building. A successful outdoor test also says little about how it will perform across several indoor floors.
How caregivers should read a location gap
Start by treating the display as uncertain, not meaningless. The last reliable point may help establish where the person entered a building or left satellite coverage. It cannot confirm that the person remained there.
Read the app carefully: Test the device in the places where it will matter. Check different rooms, floors, stairwells, parking areas, and doorways. Repeat the test rather than relying on one result, because signal conditions can vary.
- Note the time attached to the last update.
- Distinguish an exact-looking pin from a circle showing a broader vicinity.
- Check whether later updates trace movement or simply jump between estimates.
- Compare the location with likely entrances, exits, and familiar destinations.
- Do not assume that no movement on the map means the person has stopped.
Build protection beyond the tracker
Location limits matter because six in 10 people living with dementia wander at least once, and many do so repeatedly. Wandering can become dangerous or life-threatening, according to the Alzheimer's Association's wandering guidance.
A practical safety plan can combine: The National Institute on Aging presents GPS as an alternative or addition to medical identification, not a complete safeguard. A device that reports only a general vicinity cannot replace supervision or other preparations.
- A GPS tracker and medical identification.
- A current photograph that can be shared quickly.
- Neighbors who know whom to contact.
- Advance notification to local police about wandering risk.
- Attention to the tracker's charge, fit, and recent location updates.
What to do when the person is missing
Do not wait for an indoor signal to improve before starting a search. Check the immediate area and likely destinations while using the tracker as one clue among several.
An old pin, a large location circle, or a blank map should not reduce the urgency. The Alzheimer's Association recommends immediate search-and-rescue efforts and calling 911 if the person is not found within 15 minutes. Tell responders the last confirmed location, the tracker's timestamp, and whether the displayed position is precise or only approximate.
