diff --git a/src/features/online-board/components/FlightSchedule/weekDateRange.test.ts b/src/features/online-board/components/FlightSchedule/weekDateRange.test.ts
new file mode 100644
index 00000000..920bcde1
--- /dev/null
+++ b/src/features/online-board/components/FlightSchedule/weekDateRange.test.ts
@@ -0,0 +1,31 @@
+import { describe, it, expect } from "vitest";
+import { getWeekDateRange } from "./weekDateRange.js";
+
+describe("getWeekDateRange", () => {
+  it("returns Monday/Sunday for a mid-week date", () => {
+    // 2026-04-15 is a Wednesday
+    const result = getWeekDateRange("2026-04-15T10:00:00");
+    expect(result.start).toBe("13.04.2026");
+    expect(result.end).toBe("19.04.2026");
+  });
+
+  it("returns Monday/Sunday for a Sunday input", () => {
+    const result = getWeekDateRange("2026-04-19T10:00:00");
+    expect(result.start).toBe("13.04.2026");
+    expect(result.end).toBe("19.04.2026");
+  });
+
+  it("returns Monday/Sunday for a Monday input", () => {
+    const result = getWeekDateRange("2026-04-13T10:00:00");
+    expect(result.start).toBe("13.04.2026");
+    expect(result.end).toBe("19.04.2026");
+  });
+
+  it("returns empty strings for invalid input", () => {
+    expect(getWeekDateRange("not-a-date")).toEqual({ start: "", end: "" });
+  });
+
+  it("returns empty strings for undefined input", () => {
+    expect(getWeekDateRange(undefined)).toEqual({ start: "", end: "" });
+  });
+});
diff --git a/src/features/online-board/components/FlightSchedule/weekDateRange.ts b/src/features/online-board/components/FlightSchedule/weekDateRange.ts
new file mode 100644
index 00000000..76bffaf3
--- /dev/null
+++ b/src/features/online-board/components/FlightSchedule/weekDateRange.ts
@@ -0,0 +1,19 @@
+import { parseISO, startOfISOWeek, endOfISOWeek, format, isValid } from "date-fns";
+
+/**
+ * Given a scheduled local-time ISO string, return the ISO-week bounds
+ * (Monday/Sunday) as `dd.MM.yyyy` formatted strings.
+ * Returns `{ start: "", end: "" }` for invalid or missing input.
+ */
+export function getWeekDateRange(scheduledLocal: string | undefined): {
+  start: string;
+  end: string;
+} {
+  if (!scheduledLocal) return { start: "", end: "" };
+  const d = parseISO(scheduledLocal);
+  if (!isValid(d)) return { start: "", end: "" };
+  return {
+    start: format(startOfISOWeek(d), "dd.MM.yyyy"),
+    end: format(endOfISOWeek(d), "dd.MM.yyyy"),
+  };
+}