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What is an alarm flood and why does it happen?

An alarm flood is a burst of many alarms in a short time, more than anyone can read and act on. It often starts with one fault, like a power dip, that trips dozens of linked alarms together. On a phone, it looks like a wall of texts.

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Glossary

Alarm flood

In plain English, with what it means for alert texts.

Illustration of Alarm flood.

What causes an alarm flood

Most floods trace back to a single event that many points react to. A SCADA system watching hundreds of points is a common source.

  • A power failure that knocks out several sites in one go.
  • A network switch going down, so every device behind it reports as lost.
  • Chattering, where a reading hovers at a limit and the alarm flips on and off.
  • Cleared or back-to-normal messages sent for every alarm that recovers.

What the first two minutes of a flood look like

A radio repeater loses power at 2:52 AM. The first text names the cause. The ones behind it are side effects, and dozens more follow.

  • 2:52 AM, the cause: Welco: [Repeater Hill] Site power FAIL, on battery at 2:52 AM. Reply STOP to opt out.
  • 2:53 AM, side effect: Welco: [Site 14] Comms FAIL, RTU not responding at 2:53 AM. Reply STOP to opt out.
  • 2:53 AM, side effect: Welco: [Site 15] Comms FAIL, RTU not responding at 2:53 AM. Reply STOP to opt out.
  • 2:54 AM, side effect: Welco: [Site 16] Comms FAIL, RTU not responding at 2:54 AM. Reply STOP to opt out.

A phone showing these alert texts: 2:52 AM, the cause, "Welco: [Repeater Hill] Site power FAIL, on battery at 2:52 AM. Reply STOP to opt out."; 2:53 AM, side effect, "Welco: [Site 14] Comms FAIL, RTU not responding at 2:53 AM. Reply STOP to opt out."; 2:53 AM, side effect, "Welco: [Site 15] Comms FAIL, RTU not responding at 2:53 AM. Reply STOP to opt out."; 2:54 AM, side effect, "Welco: [Site 16] Comms FAIL, RTU not responding at 2:54 AM. Reply STOP to opt out."

Why a flood hurts the on-call person

The one alarm that matters gets buried in the pile. At 3 AM, nobody scrolls through forty texts to find the cause. They read the top few and guess.

Some reply STOP just to make it quiet, and then they get nothing at all. The entry on what a STOP reply does explains why that is risky.

Alarm flood vs chattering vs duplicate alerts

A flood is many different alarms at once. Chattering is one alarm flipping on and off over and over. A duplicate is the same alarm email delivered twice by a mail server.

Each has its own fix. Welco sets aside duplicate emails for you, while chattering is best tuned at the source.

How Welco keeps a flood off the phone

Alarm flood control caps how many alert emails each hour become texts. Alert rules can skip cleared or normal messages, which often cuts a storm a lot.

Fixing the source is still the best cure. The guide on how to prevent alarm floods covers tuning limits and grouping alarms. Related on-call words are in the alert texting glossary.

Frequently asked questions

How many alarms make a flood?

The ISA-18.2 alarm management standard counts 10 or more alarms in 10 minutes, for one operator, as a flood. On a phone, the practical test is simpler: any burst too fast to read.

Which alarm in a flood should I read first?

Usually the earliest one. The first alarm tends to name the cause, such as a power or comms failure, and later alarms are its side effects. Sort by time, not by how loud each sounds.

Does an alarm flood use up message credits?

Each text that goes out uses credits, so a flood can cost more than a normal night. Flood control and dropping all-clear messages keep that in check.

Is an alarm flood the same as an alarm storm?

Yes, the two names mean the same thing. Operators and standards tend to say flood, while IT teams often say storm. Both describe more alarms than a person can handle.

Stop the next alarm burst from burying your phone

Turn on flood control and skip the all-clear messages.

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