How Seattle's 911 Dispatch System Actually Works
Published April 24, 2026 · 12 minute read
If you have ever called 911 in Seattle, you may have noticed that the operator on the other end of the line asked you the same question two or three different ways, sometimes seemingly without listening to your answer. There is a reason for that, and it has nothing to do with the operator being distracted. The script the call-taker is following is a triage protocol designed to do two things in parallel: figure out what is actually happening at your location, and figure out which units to send before you finish describing the problem. This article is a plain-language walkthrough of that process, written for a general audience, with the goal of demystifying what shows up a few minutes later on the Seattle Breaking live feed.
The first six seconds: who picks up
Every 911 call placed inside Seattle city limits is routed first to the Seattle Police Department's primary public-safety answering point, generally referred to as the PSAP. The PSAP is staffed twenty-four hours a day by police call-takers, not by firefighters or paramedics. This is a deliberate design choice. Police call-takers are trained to handle the largest variety of call types and are best positioned to decide whether a call needs to stay with SPD or be transferred immediately to the Seattle Fire Department's dispatch center for fire, medical, or hazardous-materials response.
The first thing the call-taker is doing while they answer the phone is reading your phone number, your wireless carrier's best estimate of your location, and any pre-loaded address information from your wireless or landline provider. On a wireless call this location estimate can be precise (within meters, especially indoors, thanks to a technology called RapidSOS that aggregates GPS data from your phone) or it can be a several-block ellipse. The call-taker does not see your name. They do see your callback number.
The script: it isn't a script
Call-takers in Seattle follow a triage framework adapted from the International Academies of Emergency Dispatch (IAED) protocols — specifically a version called Medical Priority Dispatch System for fire and medical calls, and a parallel framework for police calls. The framework is decision-tree based: each answer you give routes the call-taker to the next branch of questions. A reported "person not breathing" routes one way; a reported "shortness of breath" routes another. The branching is deliberately tight so that two call-takers handling the same situation produce roughly the same dispatch outcome.
The reason it sometimes feels like the operator is not listening to you — for example, when you have already said "my husband is having chest pain" but they ask whether he is conscious and whether he is breathing normally — is that the protocol forces them to confirm specific facts before they can pick a code. The code, not the narrative, is what triggers the dispatch.
Determinants: turning words into a code
By the end of the triage, the call-taker has assigned the call a code. For fire and medical calls in Seattle, this code typically looks something like "29-D-2" or "10-A-1". The first number is the chief complaint (29 is "traffic / transportation incidents," 10 is "chest pain"). The letter is a determinant level that runs from Alpha (the lowest, like a stubbed toe) through Bravo, Charlie, Delta, and Echo (the highest, like an arrest in progress). The trailing number is a sub-determinant that distinguishes between, say, "chest pain with breathing difficulty" and "chest pain without."
Every code maps in the Computer-Aided Dispatch system (CAD) to a "response plan" — a pre-defined list of units to send. A Delta-level chest-pain call dispatches an aid unit, an engine company, and a medic unit (paramedics). An Echo-level cardiac arrest adds a battalion chief and may add a second medic. An Alpha-level "person down — possibly intoxicated" might only get an aid unit. The point is that the response is pre-decided by the protocol, not improvised by the call-taker.
What happens inside CAD
The CAD system is the central nervous system of the entire operation. Once a call has a code and a response plan, CAD examines the current locations of every unit in the city in real time, predicts which ones can reach the call address fastest, and dispatches them. Locations come from the automatic vehicle location (AVL) systems mounted in every SFD apparatus and SPD patrol car, transmitted continuously over the city's mobile data network.
The dispatch itself is a tone alert to the appropriate station's house alarm system (for SFD) plus an MDT — mobile data terminal — message to the unit's in-vehicle screen. Units do not need to wait for a voice radio dispatch to know where they are going; the CAD message arrives at the station within a couple of seconds of the call-taker confirming the address. The voice radio dispatch comes a few seconds later as a sanity check.
It is at this point — the CAD entry — that the event becomes visible in the Seattle Fire Department's Real-Time 911 dataset. Every record on the Seattle Breaking live feed was, at some prior moment, a single CAD record matching the description above. The dataset is generated by an automatic export from the CAD system, with personally identifying fields stripped before publication.
Code 3 vs. Code 1: lights and sirens
You may have heard the term "Code 3 response," sometimes referred to in popular usage as "lights and sirens." Code 3 is the highest-urgency response level: emergency lights on, siren active, exemption from speed limits and stop signs. Code 1 means a routine response — no lights, no sirens, obey traffic laws. There are intermediate levels in some jurisdictions but Seattle largely uses Code 3 and Code 1.
Whether a call is Code 3 or Code 1 is also pre-decided by the determinant. A Delta or Echo chest-pain call is always Code 3. An Alpha-level alarm activation is Code 1 if the building has a history of false alarms. This matters for the live feed because Code 3 responses are concentrated in the highest-severity incident types — structure fires, working medical emergencies, MVAs with injuries — and these are the events that tend to draw the visible activity (multiple units, longer on-scene times) you can see on the map.
What happens after the units arrive
Once a unit is on scene, the officer in charge can request additional resources, downgrade the response, or cancel responding units. They communicate back to the dispatcher over the radio, and the dispatcher updates CAD. This is also where the largest gap between "what the data shows" and "what actually happened" opens up. The original dispatch type is rarely updated after the fact. If a "structure fire" turns out to be burnt food and clears within ten minutes, the SFD feed will still show "structure fire." This is why we encourage readers to treat the feed as a description of what was dispatched, not as a description of what was found.
The transfer to fire dispatch
If your call to 911 is for a fire or medical emergency, the SPD call-taker will conference in Seattle Fire dispatch ("Fire on the line, go ahead, caller") rather than transfer you outright. This means you do not need to repeat the address. It also means that for a brief moment there are three people on your call: you, the SPD call-taker, and the SFD dispatcher. The SFD dispatcher is the one who finalizes the determinant for fire and medical calls. The SPD call-taker stays on the line as a safety net.
For calls that are police-only — a property crime in progress, a noise complaint, a welfare check — the SPD call-taker handles the full triage. For calls that overlap (an assault with injuries, an MVA with entrapment), both SPD and SFD will be dispatched and you may hear both on the radio.
The dispatch you'll never see on this site
Not every dispatch shows up in the Seattle Fire Real-Time 911 or SPD Call Data feeds. Specifically, the City does not publish:
- Sensitive calls related to ongoing investigations, sexual assault, juvenile incidents, or domestic violence at certain stages.
- Calls involving certain protected addresses (e.g., domestic-violence shelters).
- Calls flagged for administrative review prior to release.
- The full dispatcher-unit conversation. Audio is only available through third-party scanner services like OpenMHz and Broadcastify, and only for unencrypted frequencies. SPD tactical channels and most encrypted talkgroups are not publicly listenable.
What you see on Seattle Breaking is everything the City has chosen to release, no more and no less. The choices the City makes about what to release have changed over time and will change again. The current rules are visible in the open-data portal's data policy documentation.
How long does the whole pipeline take?
From the moment a 911 call hangs up to the moment the corresponding record appears on the public dataset is typically two to four minutes for fire and medical calls. Police data lags by hours because SPD events are not exported to the open-data feed until after their initial clearance code is assigned. From the dataset to the Seattle Breaking display takes another sixty to ninety seconds. So when you see a fire pin appear on the map, the actual dispatch usually happened three to five minutes earlier.
One more thing: the 911 system is fragile
The dispatch pipeline described above relies on a chain of systems — wireless carriers, the PSAP, CAD, AVL, the export pipeline, the open-data portal, our backend, your browser. Any one of them can fail, and during major incidents (the 2018 Mountlake Terrace transformer fire, the 2021 windstorm) several of them have. If you ever cannot reach 911, the SPD non-emergency line at 206-625-5011 and the SFD non-emergency line at 206-386-1400 are alternates for non-emergencies. For active emergencies during a 911 outage, neighbors and physical signaling are sometimes the only options.
That fragility is also why we are very firm in saying Seattle Breaking is not, and will never be, a substitute for emergency reporting. The feed exists to help you understand the city around you after the fact — not to make decisions in the moment.