Managing On-Call Across Timezones

The Global On-Call Challenge

When your engineering team spans San Francisco, London, and Singapore, on-call scheduling stops being a simple rotation problem and becomes a complex coordination challenge. Someone needs to respond at 2 AM Pacific Time, 10 AM GMT, and 6 PM Singapore Time—all simultaneously.

Organizations with globally distributed teams face unique on-call challenges that local teams never encounter. Timezone mathematics creates coverage gaps. Handoffs fail when context doesn’t transfer cleanly. Engineers work unsustainable hours because scheduling ignores their local time. Alert routing breaks when systems don’t understand that “business hours” means something different in Tokyo than in New York.

Yet global teams also have a significant advantage: properly coordinated timezone coverage means 24-hour incident response without forcing anyone to regularly work overnight shifts. The key is structure—not heroics.

Follow-the-Sun Coverage Models

Follow-the-sun on-call distributes responsibility across regional teams, with each team covering their local working hours plus a few hours on either side for handoff overlap. When the Americas team ends their shift at 6 PM Pacific, the EMEA team has already started at 8 AM London time. When EMEA ends at 5 PM GMT, APAC begins at 9 AM Singapore time.

This model works when organizations have sufficient personnel in each region to maintain sustainable rotations. A team of three engineers in each timezone can rotate weekly without anyone working permanent overnight coverage. Compare this to a single-location team where engineers rotate through overnight shifts regardless of their location, creating sustained sleep disruption.

The hardest part of follow-the-sun coverage is accepting that it requires investment in multiple regional teams. Organizations sometimes try hybrid approaches—one large US team with two engineers in Europe—which inevitably places unsustainable burden on the small regional presence. Either staff regions sufficiently or accept that someone will work nights.

Handoff Coordination Between Regions

The transition between timezone-based teams is where follow-the-sun coverage either succeeds or collapses. Effective handoffs require structured communication, not just calendar boundaries.

Each handoff should include incident status summary, current investigation state, pending actions, and context about any unusual system behavior observed during the shift. This takes 10-15 minutes of synchronous communication, which means scheduling shifts with deliberate overlap. If Singapore starts at 9 AM local time and London ends at 5 PM, there’s no natural overlap—you must create it.

Some teams solve this with asynchronous handoff documentation: the outgoing engineer writes a detailed shift report, the incoming engineer reads it and asks clarifying questions via Slack. This works for quiet shifts but fails during active incidents when context loss costs hours of re-investigation.

Better approach: schedule shifts with 30-60 minute overlaps specifically for handoffs. The outgoing engineer stays available during the incoming engineer’s first hour, available for questions but not actively monitoring. This provides continuity without doubling labor costs.

Timezone-Aware Scheduling Practices

Scheduling on-call across timezones requires more than just doing the timezone math correctly. You must account for daylight saving time transitions, regional holidays, and individual work schedules that vary by location.

Daylight saving time creates scheduling chaos twice per year. When the US springs forward but Europe hasn’t yet, the gap between regions shrinks by an hour. When Europe springs forward first, the gap widens. Systems that store times in local timezone representation rather than UTC produce incorrect shift boundaries during these transitions.

Regional holidays create another coordination challenge. US teams expect coverage on Chinese New Year. APAC teams work through American Thanksgiving. Either plan coverage explicitly or accept incidents will have slower response on regional holidays. Both choices are valid; unclear expectations are not.

Individual schedules matter more in distributed teams because “business hours” varies by region. A 9 AM meeting in San Francisco is 5 PM in London—end of day for one region, start of day for another. On-call schedules must account for standing commitments that vary by timezone to prevent conflicts.

Common Pitfalls

Ignoring Timezone Display: Alert timestamps showing Pacific Time confuse London engineers. System logs in UTC require mental timezone conversion during incidents. Every time-sensitive display should show in the viewer’s local timezone with UTC as backup.

Brittle Calendar Integration: On-call schedules that don’t automatically generate timezone-correct calendar events create confusion. Engineers miss shifts because their calendar shows incorrect local times. iCalendar feeds with proper timezone handling prevent this.

Single Team Covering Multiple Regions: Three engineers in San Francisco cannot sustainably cover 24-hour on-call by themselves. Attempting this creates burnout within weeks. If you lack multi-region teams, accept limited coverage hours rather than destroying your single team.

Ignoring Cultural Differences: Different regions have different expectations about work-life boundaries. North American engineers might accept weekend on-call as standard practice. European engineers often have stronger labor protections. On-call policies must respect regional norms or face retention problems.

Tooling for Multi-Timezone Coverage

Effective multi-timezone on-call requires tooling that understands timezones fundamentally, not as an afterthought. Systems should store all times in UTC internally while displaying in each user’s configured timezone. Shifts should generate correctly across daylight saving transitions without manual adjustment. Calendar exports should include timezone information so each engineer’s calendar displays shifts in their local time.

Alert routing should consider timezone when determining who receives notifications. Critical alerts might wake people regardless of time, but lower-severity notifications should respect quiet hours based on the recipient’s timezone, not the system’s default timezone.

Handoff coordination benefits from tooling that surfaces shift summaries, active incidents, and pending actions at the moment of transition. The outgoing engineer shouldn’t need to write a separate handoff document—the system should compile relevant context automatically from incident activity, alert patterns, and system health metrics.

Platforms like Upstat provide timezone-aware on-call scheduling with IANA timezone support per roster, UTC storage with local display, and automatic daylight saving time handling. Organizations can create multiple regional rosters—each configured in their local timezone—and coordinate handoffs between them, ensuring each team maintains their schedule in familiar local time while the system handles timezone mathematics in the background.

Multi-timezone on-call doesn’t require geographic scheduling complexity—it requires tools that treat timezones as first-class considerations rather than edge cases to work around.

Making Global On-Call Sustainable

The goal isn’t perfect 24-hour coverage—it’s sustainable coverage that doesn’t destroy your team. Accept that some hours might have slower response if you lack sufficient multi-region staffing. Acknowledge that handoffs introduce coordination overhead and plan for it.

Build explicit overlap time into shift boundaries for handoff communication. Document regional holidays and plan coverage explicitly. Configure systems to display all times in viewer’s local timezone. Use tooling that handles timezone mathematics correctly so engineers can focus on incidents rather than calendar math.

Global teams have operational advantages when structured correctly. Multi-timezone on-call makes those advantages real through thoughtful scheduling, clear handoff processes, and timezone-aware tooling that respects each region’s working patterns.