Private technical preview / aerodrome data observability
Detect missing, corrected or divergent METAR representations and source-path lag before discrepancies disappear into downstream processing.
receiptTimeexact TACLast-Modifiedexact TACfile clockexact TAC{ observation.changed }01 / THE PROBLEM
A METAR can be the same observation and still arrive through different paths with different timing, wrappers, remarks or revision state.
Live source comparison / public network
METAR LEMD 121500Z 21006KT 170V270 CAVOK 32/04 Q1020 NOSIG
d04876625abe102580cd9d8e4ceb54c13f4b9625516db713a309adb0a5718f42LEMD 121500Z 21006KT 170V270 CAVOK 32/04 Q1020 NOSIG=
8f5ff142982b5b0dae83802817f3cb3bf8668151bb288fd7b1e662dff999767cLEMD 121500Z 21006KT 170V270 CAVOK 32/04 Q1020 NOSIG
6040add3c65cece7e79d8e3987158974cb815186ae8eb00106a087b840672a7bObservation time comes from the report and identifies the weather observation.
Source time is labelled according to what that endpoint actually supplies.
Terminal Weather fetch records when this comparison snapshot was collected.
All monitored aerodromes
| Aerodrome | AWC | MET Norway | NWS mirror | Result | Open |
|---|---|---|---|---|---|
EFHKHelsinki Airport | 12/15:20Z | 12/14:50Z | 12/15:20Z | Source lag | |
EPWAWarsaw Chopin Airport | 12/15:00Z | 12/15:00Z | 12/15:00Z | Aligned | |
LFPBParis–Le Bourget Airport | 12/15:00Z | 12/15:00Z | 12/15:00Z | Aligned | |
EHAMAmsterdam Airport Schiphol | 12/14:55Z | 12/14:55Z | 12/14:55Z | Aligned | |
EGLCLondon City Airport | 12/14:50Z | 12/14:50Z | 12/14:50Z | Aligned | |
LEMDAdolfo Suárez Madrid–Barajas Airport | 12/15:00Z | 12/15:00Z | 12/15:00Z | Aligned | |
LTACAnkara Esenboğa Airport | 12/14:50Z | 12/14:50Z | 12/14:50Z | Aligned | |
LIMCMilan Malpensa Airport | 12/14:50Z | 12/14:50Z | 12/14:50Z | Aligned | |
ESSAStockholm Arlanda Airport | 12/14:50Z | 12/14:50Z | 12/14:50Z | Aligned | |
EDDFFrankfurt Airport | 12/14:50Z | 12/14:50Z | 12/14:50Z | Aligned | |
LOWWVienna International Airport | 12/14:50Z | 12/14:50Z | 12/14:50Z | Aligned | |
EIDWDublin Airport | 12/15:00Z | 12/15:00Z | 12/15:00Z | Aligned |
From evidence to service
LEMD 151230Z · TAC · timestamps · SHA-256Case files
Current snapshot / dynamic
CASE 01
LIVE / SOURCE LAG
At collection time, at least one endpoint still exposed an older nominal observation than the newest available path.
AWC 12/15:20Z / MET Norway 12/14:50Z / NWS mirror 12/15:20ZUseful forFeed migration checks, parser verification and source-path incident triage.
An archived EGCC bulletin sequence contains a NIL report, an automatic report, and a corrected conventional report for the same nominal observation. A latest-only table loses that chain.
METAR EGCC 151420Z NIL=METAR EGCC 151420Z AUTO 21011KT …METAR COR EGCC 151420Z 21011KT …Useful forRevision tracking, immutable archives and downstream replay.
The prototype keeps observation and source-receipt timestamps separate, making station-specific timing patterns visible without relabelling them as end-to-end latency.
Useful forStation baselines, threshold design and investigating a change in delivery behaviour.
The method
Fetch each public path centrally and cache the result.
Keep the exact TAC representation extracted from each endpoint response.
Hash every extracted TAC representation so identical bytes remain identifiable.
Group messages by station and nominal observation time.
Separate wrapper changes, content differences and source lag.
Practical applications
The weather is only half the operational question. The other half is whether the expected report arrived intact, on time for that path, and in the form downstream software expects.
Built for
Not a consumer weather application, pilot briefing service or official meteorological source.
Run old and new feeds side by side before changing a downstream system. Surface missing markers, stripped remarks and timestamp differences.
See whether a station is absent everywhere or only late on one route, reducing guesswork when a feed looks stale.
Retain COR, AUTO, SPECI and NIL states instead of silently replacing the previous message.
Replay exact source representations against a new decoder and detect fields lost during normalisation.
Measure completeness and source-receipt patterns by aerodrome, schedule and distribution path.
Preview coverage
The initial set spans northern, central, western and southern Europe, combining major hubs and distinct reporting environments. Stockholm Arlanda is the initial Swedish reference station.
Source clocks
JSON METAR records with nominal observation time and AWC receiptTime. Polled centrally no more than once per cache interval.
Global text product for recent METARs. Its response-wide HTTP Last-Modified value and the Terminal Weather fetch-completion time are retained; it does not supply a per-report receipt timestamp.
Latest station-coded report and HTTP file modification time. NWS describes the international observations as received from worldwide sources.
Gateway documentation ↗Private technical preview
We are inviting a small number of technical pilot conversations around feed verification, station coverage and downstream integration. No production or safety-critical use is offered.
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