Methodology & Data Sources
This site tracks daily PLA military activity around Taiwan. Every figure is transcribed verbatim from the daily public releases of the Republic of China (Taiwan) Ministry of National Defense (MND) — nothing is estimated or inferred.
Source & updates
- Single source: the ROC MND "Real-time Military Activity" bulletins and flight-path graphics — transcribed and visualized only; nothing unconfirmed by the MND is added.
- Fetched automatically after the MND publishes around midday Taiwan time (≈ 12:00–14:00); if it does not publish, that day stays blank — never filled with an estimate.
- Records are append-only and never rewritten, so cited figures stay stable; values are checked for consistency before publishing.
Lines & terms
An informal line down the centre of the strait, never recognized by any treaty. For decades both sides largely refrained from crossing it, so a crossing is a strong political signal — but it does not constitute a violation of sovereign airspace under international law and does not trigger the right of self-defense. "Median-line crossings" here means the PLA sorties that crossed it that day.
Under UNCLOS, the 12 nautical miles from the baseline are a state's territorial sea and the airspace above it is sovereign airspace — the boundary that actually carries legal weight. PLA aircraft or vessels coming inside this line is a different order of event from a median-line crossing.
Declared for the early identification of airborne objects, and far larger than sovereign airspace. Entering an ADIZ is not a violation of sovereignty; it is used to gauge intensity.
"Sorties" is the number of PLA aircraft missions detected that day; "vessels" the number of PLA Navy ships — both per the MND's own count.
PLA Activity Index (v1)
The 0–100 figure on the front page compresses the day's four observations into one number that can be compared across days. It is not an official alert level — only Taiwan's MND and national security bodies issue those. This is simply another way of reading figures already published, so a reader can tell how today compares with the past half-year.
Three design rules: reproducible (it uses only fields in records.csv, no external signals and no human judgement, so anyone can recompute it), non-drifting (the scale is a set of constants calibrated once and frozen, never recomputed against fresh history, so a score that has been cited stays put), and decomposable (the front page shows what each of the four components scored — no black box).
Each observation is mapped to a 0–100 sub-score by piecewise-linear interpolation over the knots below, then weighted:
Index = 0.35×PLA sorties + 0.35×Median-line crossings + 0.20×PLA vessels + 0.10×Active airspaces (plus 4 if the bulletin reports balloon activity; rounded and clamped to 0–100)
Zero always scores zero, deliberately: no crossing means no crossing — it does not earn a baseline score merely because most days are zero. The knots are calibrated on the actual distribution since January 2026, with the top of each scale set at historical highs.
| Component | Weight | Scale (value→score) |
|---|---|---|
| PLA sorties | 0.35 | 0→0 2→20 5→40 10→60 15→70 22→85 30→95 42→100 |
| Median-line crossings | 0.35 | 0→0 1→15 3→30 6→45 9→60 12→70 16→85 25→95 32→100 |
| PLA vessels | 0.20 | 0→0 4→20 6→35 8→50 11→70 13→80 15→90 20→100 |
| Active airspaces | 0.10 | 0→0 1→35 2→55 3→75 4→88 5→95 6→100 |
| Range | Band | Meaning |
|---|---|---|
| 81–100 | Extreme | Large-scale sortie with heavy median-line crossing |
| 66–80 | High | Air activity clearly above the norm |
| 51–65 | Elevated | Activity above the everyday baseline |
| 31–50 | Normal | Routine activity at everyday scale |
| 0–30 | Low | Little or no air activity; naval presence only |
The ▲▼ arrow compares today's index with the average of the last 7 days that have data, and only shows a direction when the gap exceeds 5 points. Day-over-day comparison is not used: this data is bursty (median day-to-day swing ≈ 16 points), so it would flag a direction almost every day and carry no information.
The site's colour scheme follows the same index: days scoring 66 or above render the whole site dark, everything else light.
Should the scale ever need recalibrating (for instance if PLA activity shifts upward enough that the scale loses discrimination), the version number will increment and the change will be documented here. Past scores are not rewritten.
The arms dataset
The Arms Delivery Tracker is a separate dataset covering US Foreign Military Sales to Taiwan notified to Congress by the Defense Security Cooperation Agency (DSCA) since 2019. A DSCA notification is not a signed contract or a delivery, and notified values are ceilings. Direct commercial sales are excluded; every case is compiled by hand with its own source link.
Citation & license
The underlying figures are public information from the MND. This site's compilation, field structure and charts are released under CC BY 4.0. Please credit:
Source: ROC Ministry of National Defense; compilation & charts: PLA Activity Tracker (https://pla-tracker.skyfaring.net).
Raw data (CSV): https://pla-tracker.skyfaring.net/data/records.csv