What is alarm flooding, and how can it be prevented?

What alarm flooding is

Alarm flooding is the state in which the number of alarms in a period exceeds what an operator can respond to meaningfully. It can come from one large failure or from many small deviations across a system. When the operator has to work through each alarm in turn, the risk of missing the critical one rises.

A cascade alarm is a chain of alarms that follows a single source failure, and most of them share the same cause. Alarm flooding is a design problem in the alarm system. A new software package or an AI model does not solve it by itself.

Example: a 10-minute window

An operator sees 60 alarms in a 10-minute window (hypothetical). Of these, 36 come from one level alarm that keeps chattering, and 24 come from other alarms. A deadband and an on-delay are added to the chattering alarm, so it now produces only one event. The new total is 1 + 24 = 25 alarms. That is still above ten, so the flood remains. One fix is not enough: the other 24 alarms need prioritisation and suppression as well. The total fell from 60 to 25, a 58.3 percent reduction (35 / 60).

Common mistakes and order of work

The first mistake is raising thresholds at random to reduce the count, which also hides real risks. The right order starts with alarm rationalisation: each alarm needs an operator action, a priority and an acceptable response time. The second mistake is adding only a delay to chattering alarms and skipping the deadband. The third is failing to document suppression used during maintenance or start-up. Adding new alarm types before the count is under control makes the problem worse.

Follow-up questions