"For an hour and a half, he didn't know anyone was calling."
That's how one medical device manufacturer described a communication breakdown on their floor. A technician was in another building, unreachable, while operators kept pressing the call button. No one tracked it. No one reported it. The wait time simply vanished—along with 90 minutes of production.
Most plants are meticulous about tracking machine downtime. When a CNC goes down, the MES logs it. When a conveyor stops, it shows up in the shift report. But what about the time operators spend waiting for help that never comes?
That's the hidden downtime most plants don't track—and it's costing more than you realize.
Visible Downtime vs. Hidden Downtime
Manufacturing plants typically track what's easy to measure: machine downtime. Your MES captures when equipment stops running. Your shift reports show unplanned maintenance events. Your OEE calculations include availability losses.
But there's another category of lost time that rarely shows up in any report: human wait time.
Consider the difference:
Visible downtime:
- Machine breaks down
- PLC logs the event
- Maintenance responds
- Repair time is recorded
- Operator has a problem
- Operator calls for help
- Help doesn't come (or is delayed)
- Operator waits—untracked
The Wait Time Nobody Tracks
Here's a scenario that plays out daily in manufacturing plants: "It's been 5 minutes and no one has come to cell two."
Five minutes doesn't sound like much. But consider what's happening during those five minutes:
- The operator can't continue working
- The problem isn't getting solved
- Other cells may be affected downstream
- The delay compounds with each passing minute
Types of Hidden Wait Time
Wait time comes from multiple sources:
Waiting for maintenance. Equipment has an issue, but the maintenance tech is handling something else. Or didn't get the alert. Or didn't know which call to prioritize.
Waiting for quality. A defect appears, and production can't continue until a quality inspector signs off. But where's the inspector?
Waiting for materials. Parts run out, but the material handler is across the facility. How long until they arrive?
Waiting for a supervisor decision. Something unusual happens, and the operator needs approval. But the supervisor is in a meeting, or on another line, or out of range.
Each of these wait times shares one thing in common: most plants don't measure them.
Calculating the True Cost
Let's make this concrete. Consider a manufacturing cell with one operator earning $25/hour (fully loaded cost).
| Factor | Value |
|---|---|
| Calls per day | 6 |
| Average wait time per call | 8 minutes |
| Daily wait time | 48 minutes |
| Cost per day | $20 |
| Cost per week (5 days) | $100 |
| Cost per year (50 weeks) | $5,000 |
Now multiply by the number of stations on your floor. A plant with 20 production cells could be losing $100,000 annually in untracked wait time.
And this calculation assumes eight-minute average waits. When one manufacturer described "an hour and a half" of missed calls, the math gets much worse.
Common Sources of Hidden Idle Time
Based on how manufacturing plants describe their challenges, hidden downtime typically comes from a few predictable sources:
Communication Failures
The most common culprit: the call went out, but the response team didn't receive it.
Radios get missed in noisy environments. Intercoms don't reach the back of the facility. Pagers run out of battery. The operator thinks they called for help. The maintenance tech never knew.
No Escalation
What happens when the first call goes unanswered?
In many plants, nothing. The call sits there. The operator waits. Maybe they try again. Maybe they leave their station to go find someone—which creates even more lost time.
One manufacturer noted the need for automatic escalation: "If the call's been over 10 minutes, you can have it send multiple reminders." Without that capability, calls simply sit.
Operators Leaving Stations
"What I would like is that the operators don't need to go around looking for help as they're doing now."
When communication systems fail, operators improvise. They leave their stations. They walk the floor searching for maintenance techs. They interrupt supervisors in meetings.
That walking time is productive time lost—twice. The operator isn't producing, and they're pulling others away from their tasks.
Responders Don't Know Priority
"All just respond to calls whenever they get it."
When there's no coordination, responders handle calls in random order. High-priority issues wait while minor problems get attention. Multiple people respond to the same call while others go unaddressed.
Why Traditional Tracking Misses It
If this lost time is so costly, why don't plants track it?
MES Tracks Machines, Not People
Your Manufacturing Execution System is excellent at capturing equipment states: running, stopped, faulted. But the MES doesn't know that an operator pressed a call button. It doesn't know that eight minutes passed before anyone responded. It captures production output, not communication gaps.
Radios and Intercoms Leave No Records
Radio conversations vanish the moment they end. There's no log of who called, when, whether anyone responded, or how long it took.
One manufacturer evaluating their legacy system discovered: "No metrics tracking." Their paging system worked—calls went out, pagers received them—but there was no data. "No time tracking for issue resolution."
Spreadsheets Can't Capture Real-Time Events
Some plants try to track response times manually. Operators fill out forms. Supervisors enter data into spreadsheets. But this approach has obvious problems:
- Data entry happens after the fact (if at all)
- People underestimate wait times
- There's no automatic timestamp
- It adds administrative burden to operators
Real Examples from Manufacturing
These scenarios come from manufacturers describing their own situations:
Medical Device Plant: 90 Minutes Invisible
A technician spent an hour and a half in an adjacent building, out of range. Operators kept pressing the call button. No one tracked the accumulated wait time. The technician didn't know. Supervision didn't know. The gap only surfaced when someone mentioned it in conversation.
Food Manufacturing: 8 Lines, No Visibility
A food plant with eight production lines upgraded from a basic paging system because it lacked reporting. Their pain point: "No time tracking for issue resolution." They knew calls were happening but couldn't prove how long responses took or identify patterns.
HVAC Manufacturing: Stuck and Waiting
"I walked by the other day and you know they're stuck in a machine." An operations manager witnessed the problem directly—but how often does it happen when no one walks by? Without tracking, these events remain invisible.
How Response Time Tracking Helps
The solution isn't complicated: track the time between "call made" and "help arrived."
Effective response time tracking captures two distinct measurements:
Wait time: How long did the operator wait before someone acknowledged the call?
Resolution time: How long did it take to fix the problem once someone arrived?
As one manufacturer described it: "It's going to stop the initial timer to let you know how long they waited for the call, but it's going to start a new timer to let you know how long they're working on that issue for."
What Good Tracking Provides
Timestamps. Every call is logged with time and location. No more guessing.
Accountability. You can see who responded to which calls and how quickly.
Escalation data. Track which calls required escalation and why.
Historical trends. Identify patterns: Which stations have the most calls? Which shifts have the longest wait times? Which call types take longest to resolve?
Improvement targets. You can't set goals for response time if you don't measure it.
Frequently Asked Questions
What's the difference between downtime and wait time?
Downtime typically refers to when equipment isn't running. Wait time refers to when operators are idle because they're waiting for support—even if the machine could run.
How do I calculate my hidden downtime costs?
Start with estimates: (Calls per day) × (Average wait time) × (Hourly labor cost) × (Number of stations). Even rough numbers reveal the scale of the problem.
Why doesn't my MES capture this?
MES tracks machine states, not human communication. It knows when equipment is running or stopped, but it doesn't know that an operator has been waiting 10 minutes for a quality inspector.
What should I track?
At minimum: time from alert to acknowledgment, and time from acknowledgment to resolution. Advanced tracking adds call type, responder, location, and escalation history.
Taking the Next Step
Hidden downtime is a solvable problem. The first step is acknowledging it exists—and that most plants aren't measuring it.
The second step is implementing tracking that captures the gap between "help needed" and "help arrived."
If you're ready to explore systems that make this visible, start by understanding what's available.
Related reading: