An arrival window is the range of time a field service company promises a customer that the technician will arrive, such as "between 8:00 and 12:00." It covers arrival only, not how long the job will take.
How an arrival window is measured
Two numbers describe a window: its width and whether you keep it.
Window width = Latest promised arrival − Earliest promised arrival
Window kept = Actual arrival falls between the earliest and latest promised times
Across many jobs, the second becomes your on-time arrival rate. A narrow window you miss is worse than a wide one you keep, so read the two numbers together.
Why it matters for scheduling
Window width is a hedge against uncertainty. The less a scheduler knows about when the truck will really get there, the wider the window has to be. Two things drive that uncertainty:
- Job duration. If the job before this one could take one hour or three, every job after it inherits that spread.
- Travel. If the drive from the previous job was never calculated, the scheduler pads for the worst case.
That is why the first job of the day usually gets a tight window and the last job gets a wide one. The uncertainty stacks up through the day. The mechanism is laid out in Why arrival windows are so long.
Narrowing a window means removing one of those sources of uncertainty, not just promising a smaller range. Better job duration estimates shrink the first. Computing the drive from where the truck will actually be, at booking time, shrinks the second. That second part is what CrewLink does: it checks travel feasibility before a slot is offered. Practical steps are in How to shrink your arrival window.
A common mistake
Setting one window width for every job. A four-hour window on a first call of the day wastes the customer's morning for no reason. The same four hours on a fifth call after two long repairs may still be too narrow. Width should follow the uncertainty of the specific slot.
Related terms
- Service window is the time range when work can happen, which can differ from the arrival promise.
- On-time arrival rate is how often the window is kept.
- Travel-feasible scheduling is the practice that makes tighter windows safe to promise.
Common questions
What is a typical arrival window?
Many companies use two- or four-hour windows, often split into morning and afternoon. There is no correct width. The right width is the narrowest one your schedule can keep reliably.
Is an arrival window the same as an appointment time?
No. An appointment time is a single point. An arrival window is a range, used because field service schedules cannot predict a single arrival minute days in advance.
How do you shorten arrival windows without missing them?
Reduce the uncertainty behind them: estimate job durations from your own history and calculate travel from the previous job when the slot is booked.