On-call · 7 min read · 2026-10-29

Gaps in on-call coverage: where they come from and how to prevent them.

Most gaps in an on-call schedule show up after it's published: a physician falls ill at noon on Friday, leave gets approved without anyone checking call, a swap is settled in the hallway. To prevent them, don't approve leave until the shifts in that period are swapped, don't accept a swap that isn't on the schedule, and write down that the scheduled physician stays on call until a replacement is entered in their place. Here are the situations we see most often, and how a team can organize to avoid them.

By Kamel Gorieze

Co-founder · product and user experience

In short

Most gaps show up after publication: a last-minute withdrawal, leave approved without checking call, a swap never recorded, a weekend split across two months, or an old copy at the switchboard.
The scheduled physician stays on call until a replacement is entered in their place. Letting people know starts the search, but it doesn't release the shift.
Leave shouldn't be approved until the shifts in that period have been swapped.
Every slot on the schedule shows start and end times, not just the day.
At the bottom of the schedule, the escalation chain says who to call when a gap happens anyway: the person who keeps the schedule, then the chief of department.

What counts as a gap

A gap is when the ward nurse, the ER or the switchboard operator calls the on-call physician and finds nobody. Sometimes the slot is empty. More often there's a name in it, but that physician isn't on call that night: they swapped, they're on vacation, or they thought their weekend ended on Sunday evening. The same situations come up from one team to the next, in FMGs and hospitals alike.

Where gaps come from

1. The Friday-noon sick call

A physician falls ill at noon on Friday and tells the person who builds the schedule. As far as they're concerned, it's handled. The person who builds the schedule starts calling colleagues one by one, who are in clinic, in the OR or already gone for the weekend. Meanwhile, if the rule isn't written down, nobody really knows who's on call.

2. Leave approved without checking call

The person who approves leave is often not the one who builds the schedule. A physician gets their vacation approved in February, the information stays in an email, and the March schedule comes out with their name on a Thursday that week. They never sent an unavailability, because as far as they were concerned, it was already settled.

3. The swap nobody recorded

Dr. A and Dr. B agree between two patients to swap Tuesday the 13th for Thursday the 22nd. Nobody writes it down, and the schedule still says A on the 13th. If Dr. B forgets, the switchboard calls Dr. A, who thinks they're off. This one is hard to spot ahead of time, because the schedule looks complete.

4. The weekend split across two months

With monthly schedules and weekends from Friday 5 p.m. to Monday 8 a.m., a block sometimes starts in one month and ends in the next. In 2027, that happens on Friday April 30. The April schedule puts a name on the 30th. The May schedule starts on Saturday the 1st with an empty cell, because whoever builds it assumes the block is already covered. Holidays next to a weekend, like Easter Monday, cause the same kind of confusion.

5. The old copy at the switchboard

The schedule is right, but only in the file of the person who builds it. The switchboard, the ER or the wards are working from the version printed two weeks ago, before three swaps.

How to organize against gaps

Tie leave to call

Leave approved without checking the schedule is fixed in the leave request itself. Add one question: "Do you have call during this period, and who have you swapped with?" The leave is approved once that's settled. The person leaving finds the swap weeks ahead, instead of the person building the schedule finding out three days before.

For periods when everyone wants to leave at once (summer, spring break, the holidays), set the vacation deadline earlier than usual, before you build the schedule. Our article on the holiday schedule shows how to share those weeks out.

Write the times in every slot

"April 30, Dr. E" doesn't say until when Dr. E is on call. Write "Friday April 30, 5 p.m. to Monday May 3, 8 a.m." instead. That clears up most of the confusion about weekends split across two months and long holiday weekends. Add the rule for those cases at the bottom of the schedule, for example: a shift belongs to the schedule of the month it starts in.

Only recognize recorded swaps and replacements

A swap agreed between two patients is fine. The person who keeps the schedule just has to get it in writing, from both physicians, and send out the new version the same day. Until then, each keeps their original shift. Have one way to send swaps that everyone knows: an email address, a messaging group or the software.

The same rule applies to a withdrawal: the scheduled physician stays on call until a replacement is entered in their place. Letting people know starts the search, but it doesn't release the shift. Our article on shift replacement explains how to find someone faster.

Give the switchboard the week's list

A monthly schedule printed on the 1st is out of date after the first swap. What the switchboard and the ER actually need is a short page: who's on call this week, from what time to what time, at what number, with the version date. Send it again in full with every change, and ask them to throw out the old one.

Write the escalation chain at the bottom of the schedule

Even with all that, a gap will happen eventually: the on-call physician falls ill on a Saturday evening, and nobody has been found to replace them yet. Write at the bottom of the schedule who to call, in order, with their numbers: the person who keeps the schedule, then the chief of department, or the physician in charge in an FMG. At 3 a.m., the switchboard operator doesn't have to guess.

Where to start

No need to change everything at once. For your next schedule, do three things.

Write the times in every slot, and the escalation chain at the bottom of the schedule.
Write under the schedule that a swap or replacement only counts once it is recorded.
Add the call question to your leave requests.

The rest can wait for the next meeting. All of this works fine in an Excel file, as long as one person keeps the schedule and everyone knows who that is. For building the schedule itself, see our step-by-step method, and for writing the team's rules on one page, our article on fair on-call distribution.

Where Synchro fits in

Synchro generates the schedule from the types of call and the rules the team has defined. Each physician writes their unavailability in plain language, in their own words, and rest rules are applied when the schedule is generated. The dashboard shows covered slots, conflicts and pending transfers.

When a physician can no longer cover a shift, they post it on the transfer board. Eligible colleagues are notified at the same time, the schedule updates when one of them takes it, and the transfer is counted in the fairness counters. Everyone sees the same schedule in the team calendar, and can add it to Google Calendar or their Apple calendar. There is only one version of the schedule.

The limits, to be clear. Synchro is not an establishment-wide on-call directory and does not send code alerts: the department has to give the switchboard access or an up-to-date copy. Synchro does not decide the team's rules, does not calculate on-call pay and holds no patient data. There is no native app, but the web interface works on a phone.

Frequently asked questions about on-call coverage gaps

What is a gap in an on-call schedule?

It is a moment when someone looks for the on-call physician and finds nobody. Either the slot is empty, or it carries the name of a physician who is not on call that night, because they swapped, they are on leave or the copy being used is old.

How do you prevent gaps in an on-call schedule?

Don't approve leave until the shifts in that period have been swapped. Treat a swap as nonexistent until it is on the schedule, and the scheduled physician as on call until a replacement is entered in their place. Write start and end times in every slot, give the switchboard an up-to-date list for the week, and write at the bottom of the schedule who to call when a gap happens anyway.

How do you make sure the switchboard and the ER have the right on-call schedule?

Give them a short page for the week: who is on call, from what time to what time, at what number, with the version date. Send it again in full with every change, the same day, and ask them to throw out the old one.

Who is responsible for a shift when the scheduled physician can no longer cover it?

The team's rule decides, and it is best written down. The safest one: the scheduled physician stays on call until a replacement is entered in their place. Telling the person who builds the schedule starts the search, but it does not release the shift.

Which schedule owns a weekend on call that straddles two months?

Whichever one the team has chosen in writing. The simplest rule is that a shift belongs to the schedule of the month it starts in. A block that starts on Friday April 30 at 5 p.m. is on the April schedule, even though it ends on Monday May 3. Write the full times in the slot, and note it at the top of the May schedule.

How much does Synchro cost for an on-call schedule?

For an FMG or a clinic, $10 CAD per user per month, the first month free and every feature included. For a hospital department, it is free for the whole beta phase.

The physicians, swaps and leave described are examples built for illustration from situations we have observed, not identifiable real cases. Product names belong to their respective owners and this site is not affiliated with any of them.

About the author

Kamel Gorieze