This simulator lays an unplanned outage and a scheduled maintenance window on a single observation timeline and computes availability from the minutes of uptime. It makes the denominator visible and shows why the answer depends on whether maintenance counts as downtime.
• A 3D observation timeline with an unplanned-outage lane, a maintenance lane and a live service conveyor that loops through the window. • Sliders for observation window (4-12 h), unplanned outage start (30-360 min) and duration (15-120 min), and maintenance start (30-360 min) and duration (15-120 min). • Six live readouts: availability including maintenance, availability excluding maintenance, total union downtime, planned downtime, window uptime and playback position in minutes. • Two presets: Overlapping downtime (the union is 60 minutes, not 120) and Separate interruptions (inclusive availability 360/480 = 0.75).
Downtime D is the duration of the union of the unplanned and planned intervals within the window, so overlapping minutes are counted once. Inclusive availability is A_inclusive = (W - D) / W. Excluding scheduled maintenance from the denominator gives A_excluded = (W - D) / (W - planned duration). Both use the same productive uptime; only the eligible time in the denominator changes.
This is a deterministic observation window, not a stochastic reliability model. Only scheduled maintenance is excluded from the alternate denominator, and playback runs at 15 observed minutes per animation second and loops. Move the maintenance window on top of the outage and watch the union shrink, then separate them and watch both availability figures change.
No. Downtime accounting uses the union of the intervals, so two events covering the same 30 minutes contribute 30 minutes, not 60.
Yes. Excluding scheduled maintenance reduces the eligible observation time, which raises the availability figure even though the uptime is the same.
A = (W - D) / W, where W is the observation window and D is the union of downtime. The alternate definition divides by (W - planned duration).
It is deterministic and does not model random failures, repair-time distributions or partial degradation. Availability is computed only from the intervals you set.