How Briefway works.

Type a departure and arrival ICAO code (optionally up to three alternates) and Briefway fetches NOTAM, METAR/TAF, en-route SIGMET and freezing-level forecast points plus an aeronautical map overlay for that route, then plots and decodes them into a single page: a route map, a NOTAM list, a weather panel, an en-route SIGMET panel, a freezing-level route summary, and a library of links to the official AIP for every country the route touches.

It does not generate or interpret data beyond what its sources publish - it re-formats and geographically filters public feeds so you read one page instead of four separate tools.

Route - enter departure and arrival as 4-letter ICAO codes (e.g. LIRF), or start typing a city or airport name (e.g. MILANO) and pick from the suggestions. Both endpoints are checked against a station database before the briefing runs. Add up to 3 alternates with "+ ALTN".

Choose on map- don't know the code? The "▦ MAP" button on any route field opens a picker: tap near the field to select the nearest airport, or drop a free coordinate point for an airfield with no ICAO code. See choosing a point on the map.

Cruise GS - your planned ground speed in knots (40-600 kt), used to estimate the time you will reach each NOTAM/SIGMET/en-route station along the route, and to compute an arrival time from an entered departure time. Three presets are provided - VFR ~100 kt, Turboprop ~250 kt, Jet ~450 kt - but you can type any value in range.

ETD / ETA - optional estimated departure and arrival times in UTC. When set they anchor the along-route time estimates and filter NOTAM and SIGMET to your flight window; see flight timing.

History - routes you brief are remembered locally (last 20) so you can re-open them with one click; see what stays on your device.

Share & print - the briefing page header lets you copy a link that reproduces the same route/alternates/ground speed for someone else, or print a compact summary. The printout is titled with the flight (DEP - ARR) and date, and the saved PDF takes the same name.

Edit the route on the map- the map's edit button lets you drop, drag and remove intermediate waypoints. Pressing Apply updates the URL and re-fetches the briefing for the new track. See editing the route on the map.

Personal alerts & GPS - the NOTAM panel can store your own local alert rules, and the map can show your current browser GPS position when you press the locate button. Neither one changes the route or the server-side briefing.

The banner at the top of a briefing (GO CHECK / ATTENTION / CRITICAL) is a deterministic checklist, not a model judgement. Each rule below can only raise the level, never lower it, and every triggered rule is listed as a reason under the banner:

• CRITICAL - any departure/arrival/alternate airport reporting LIFR; an active NOTAM classified CRITICO on one of those airports; or a SEV-qualified SIGMET along the route.
• ATTENTION - any airport reporting IFR or MVFR; one or more active ALTONOTAM; any SIGMET along the route (when none is SEV); freezing level at or below 3,000 ft AMSL along the sampled route; or a NOTAM/freezing-level source being unavailable (treated as a warning, never as "zero NOTAM" or "no freezing risk").
• GO CHECK - none of the above triggered for this route at fetch time.

Below the quick read, a data freshness line tracks how old the oldest of the weather/NOTAM/SIGMET/freezing-level fetch timestamps is, ticking forward every minute: fresh under 20 minutes, a watch notice from 20-30 minutes, and a re-check prompt past 30 minutes - matching the typical METAR/TAF update cadence.

If one of your personal NOTAM alert rules matches the current briefing, the banner adds a custom alerts line. Critical custom matches are called out separately, but they do not alter the underlying fetched data.

Each time you open a route, Briefway saves a small snapshot of that briefing in your browser. The next time you open the same route, it compares the two and, if anything moved, shows a CHANGES SINCE LAST CHECKbanner listing what differs - for example a new or cleared critical NOTAM, a shift in any airport's flight category, or a change in the number of en-route SIGMET.

The comparison is entirely local: it only ever diffs your own previous view of that route against the current one, so the first time you brief a route there is nothing to compare. The snapshot lives only in localStorage (see what stays on your device).

NOTAM are fetched for every airport on the route and plotted on the map when they carry coordinates; those that fall within ~100 nm of the route also show an estimated time-along-route in the list. Each one gets a status from its validity window - ATTIVO · IN_SCADENZA (≤24h left) · IN_ARRIVO · PERMANENTE · SCADUTO - and a severity derived first from the NOTAM text and, if that finds nothing, from its Q-code subject/condition:

• Critical - aerodrome or runway closed.
• High - ILS/GPS/GNSS/RAIM unserviceable or not available, a taxiway closed, or a restricted/prohibited airspace.
• Medium - obstacles, cranes, lighting, work in progress, fuel.
• Info - everything else.

The plain-language line under each NOTAM is a deterministic, rule-based decoding of standard ICAO abbreviations (e.g. RWY → runway) - not an AI summary. The original raw text is always shown alongside it; treat the decoding as a reading aid, not the authoritative wording.

When an ETD/ETA window is set, NOTAM that can't be active during the flight (ending before departure or starting after arrival) are filtered out; permanent NOTAM are always kept. See flight timing.

If you haven't connected autorouter yet, or a fetch fails, the panel shows an explicit "NOTAM data not available"notice instead of an empty list - an empty NOTAM panel always means the source returned zero NOTAM, never that the source wasn't checked.

The Alert Rules control in the NOTAM panel lets you create local rules that highlight NOTAM relevant to your own operation. Rules can match severity, status, category or Q-code, ICAO, keywords, distance from the route, and validity window.

Keyword matching is simple and deterministic: the terms you enter are compared case-insensitively against the original raw NOTAM text plus the decoded reading aid. Briefway does not run user-defined regular expressions and does not send your alert rules to the server.

Matching NOTAM get a CUSTOM ALERT badge in the list and a dedicated halo on the map. Rule preview counts update in the editor before you save, so you can tune a rule without changing the briefing fetch.

Current METAR and the latest TAF are fetched for every route airport, plus nearby reporting stations within the route corridor for an en-route picture. Each METAR is assigned a standard ICAO/FAA flight category from ceiling and visibility:

• LIFR - ceiling below 500 ft or visibility below 1 sm.
• IFR - ceiling below 1,000 ft or visibility below 3 sm.
• MVFR - ceiling 1,000-3,000 ft or visibility 3-5 sm.
• VFR - better than the above.

When the source publishes its own flight category for a station, that value is used as-is; the thresholds above are only the fallback computed from ceiling/visibility.

Nearest-station fallback - if an airport has no METAR of its own (common for small fields and map-picked points), the card shows the closest reporting station that does, labelled NEAREST STATION with the distance in NM, so you still get real nearby conditions.

Each card also decomposes the reported wind into per-runway components - see runway wind components.

The separate EN-ROUTE WEATHER panel lists the reporting stations inside the route corridor, each with its flight category, how far along and off the track it sits, an estimated time you would pass it, and its wind, visibility, cloud and freezing-level readings. An empty list means no station was found in the corridor, not that the lookup was skipped.

Under each airport's METAR, the RWY WIND block breaks the reported wind down for every runway end, so you don't have to do the trigonometry in your head. For each end it shows the along-runway component (headwind ↓ or tailwind ↑) and the crosswind component with the side it comes from (←/→), in knots.

The end most into wind - the most headwind, least tailwind - is flagged BEST. Runway headings come from the OurAirports dataset (true-north referenced, like the METAR wind), so no magnetic correction is applied. Calm or variable winds are shown as such, with no components.

This is decision support, not an authorisation: always cross-check against the active runway and your aircraft's crosswind limits.

Under each airport's runway wind block, the DENSITY ALT panel shows the altitude the air at that field currently feelslike to your aircraft. It is computed locally from three values the briefing already has: the field elevation, and the temperature and QNH in that airport's own METAR.

• Pressure altitude - field elevation corrected for the QNH, using the standard-atmosphere relation (about 27 ft per hPa, rather than the rougher 30 ft/hPa rule of thumb).
• ISA deviation - how far the reported temperature sits above or below the standard atmosphere at that pressure altitude.
• Density altitude - the pressure altitude plus about 119 ft for every degree C above ISA. The second figure tells you how far that sits above the field you are actually using.

The band is advisory: ELEVATED from 5,000 ft density altitude or 2,000 ft above the field, HIGH from 7,000 ft or 3,000 ft above the field. A warm summer day at a sea-level airport stays NORMAL on purpose - the number is always shown, the band only escalates when it is worth a second look. An escalated band at departure or arrival also appears in the quick read.

Briefway deliberately stops here and does not estimate take-off or landing distances: those are aircraft-specific and belong to your AFM/POH. Density altitude is the input you take to those charts.

It is only computed from the field's ownMETAR. If an airport has no METAR and the briefing falls back to a nearby station, no density altitude is shown - another field's pressure and temperature would produce a meaningless figure. The same applies when the elevation, temperature or QNH is missing.

The DAYLIGHT & TWILIGHT panel gives sunrise, sunset and the civil-twilight bracket for departure, arrival and every alternate, all in UTC. Nothing is fetched for this: it is a solar-position calculation run locally from the airport coordinates, so it also works with no connection.

Each airport is judged at the moment you are actually there - the ETD for the departure field, the ETA for the arrival and the alternates - and badged DAY, TWILIGHT or NIGHT.

The night warning only appears when you enter an ETD or ETA. Without them the briefing is a "depart now" brief: the times are still shown for reference, but the sun's position right now says nothing about a flight you are planning for later, so Briefway does not raise a night-operation flag it cannot support. When you do set the times and a leg falls outside daylight, the panel and the quick read both say so.

Above the Arctic and Antarctic circles the panel reports polar day or polar night explicitly rather than showing blank times.

Accuracy is around a minute at temperate latitudes and degrades toward the poles. Aviation "night" is defined nationally - EASA uses the end of evening civil twilight to the beginning of morning civil twilight, others use sunset to sunrise - so both pairs are shown and you apply your own rule. This is planning information, not a legal night-time reference.

The route form has an optional Cruise ALT field in feet AMSL. Set it and Briefway samples the forecast wind and temperature at your planned level along the route; leave it blank and nothing is queried at all, so a briefing that does not need it stays exactly as fast as before. Tapping an active preset again clears it.

The data comes from Open-Meteo's pressure-level model - the same key-less source used for the freezing level. Your cruise altitude is matched to the nearest standard pressure level (850, 700, 500, 250 hPa and so on), and the panel always shows which level was used and its standard altitude, plus how far that sits from the altitude you asked for when the gap is 500 ft or more.

• Mean along track - the wind resolved against the route bearing at each sample and averaged: a headwind or a tailwind in knots. This is the figure that moves your fuel plan.
• Strongest wind and coldest point - with how far along the route each one sits.
• A per-point table of wind and temperature, in along-route order.

Winds above 50 kt at the cruise level, or a mean headwind above 25 kt, are raised in the quick read.

This is numerical model forecast data, not a published aviation wind chart and not an official upper-wind forecast. It complements, and never replaces, the SIGMET and SIGWX charts above it.

The ALTERNATE SUGGESTIONS panel searches the airport dataset around your destination and ranks what it finds. Nothing is fetched until you press FIND ALTERNATES, so the panel costs nothing if you never open it.

Two filters drive the search: a minimum runway length and a maximum distance from the destination. Airports already on your route are excluded, as are heliports, seaplane bases and balloonports.

Each candidate is graded on runway length and the conditions reported there:

• SUITABLE - VFR reported and the longest runway meets your minimum.
• MARGINAL - MVFR or IFR reported, or something is unknown: no METAR at the field, or no runway length in the dataset. Unknowns are never quietly promoted.
• UNSUITABLE - LIFR reported, or the longest runway is shorter than your minimum.

Every card lists the reasons behind its grade, plus distance and bearing from the destination, runway count, elevation and the current wind, visibility and cloud - so you can disagree with the grade on the evidence rather than take it on trust.

This is a shortlist to investigate, not a legal alternate selection. Fuel, approach minima and availability, opening hours, PPR, customs and the NOTAM at each field are all outside what these inputs can see. Check them in the AIP and the official briefing before you file.

A snapshot freezes the whole briefing exactly as it is on screen and stores it on the device, with a validity window you choose (30 minutes, 1 hour or 3 hours). It is meant for the gap between reviewing a brief on the ground and flying it: the page stays readable with no signal, and its data can never silently change underneath you.

Open the SNAPSHOTS panel at the bottom of a briefing, pick a validity and press SAVE SNAPSHOT. Saved snapshots are listed with when they were taken, how old the data in them is, and how long is left in their window. OPEN loads one.

A briefing opened from a snapshot is clearly banded as frozen: it shows the capture time, the true age of the data, and it does not refresh. Once past its window it is banded EXPIRED SNAPSHOT and tells you to re-check live data. BACK TO LIVE returns to the live briefing for the same route. A frozen briefing is also never used as the baseline for changes since last check.

Snapshots stay in this browser. Nothing is uploaded, there is no account and no server-side copy, which also means a snapshot does not follow you to another device. To move one, use EXPORT to save it as a file and IMPORT FILE on the other device. The eight most recent snapshots are kept; expired ones are cleared automatically.

Briefway installs a small service worker that keeps a copy of the app and of the last data it successfully loaded, so opening the briefing with no signal shows something useful instead of a browser error page. You can also install Briefway to your home screen and run it like an app.

The cache is strictly a fallback. Every request goes to the network first, and the stored copy is only used when the network actually fails - a connected device always shows live data.

When the browser reports no connection, an OFFLINE banner appears at the top of the briefing stating that nothing is refreshing and exactly how old the data on screen is. Because a cached briefing keeps its original generation time, the age you are shown is the real age of the weather, NOTAM and SIGMET in front of you - stale data is never presented as current.

What is cached: the app shell, map tiles you have already loaded, and the last successful response for the routes you have viewed. What is never cached: anything tied to your autorouter sign-in, and the source diagnostics endpoint.

For a briefing you know you will need in the air, prefer a snapshot: it is explicit, it carries a validity window you chose, and it cannot be evicted by the browser reclaiming cache space.

The route form has optional ETD and ETA fields, entered in UTC (Zulu). If you set an ETD and leave ETA blank, Briefway estimates the arrival time from your cruise ground speed and the route distance.

When a departure time is set, the along-route time estimates on NOTAM, SIGMET and en-route stations are anchored to it instead of "depart now". The flight window then filters what you see:

• SIGMET - already-expired ones are always dropped; with a window, ones ending before departure or starting after arrival are dropped too.
• NOTAM- with a window, ones that can't be active during the flight are hidden; permanent NOTAM are always kept.

The chosen ETD/ETA also appear in the header readout and set the flight date used on the printout and PDF filename. With no times set, the briefing behaves as before ("depart now").

Freezing level is fetched separately from METAR/TAF because those reports do not publish a route-wide freezing level. Briefway queries Open-Meteo's forecast field freezing_level_height for each route airport, nearby en-route weather station, and up to 10 samples along the planned track. Values are converted from metres to feet AMSL and shown as forecast data.

The quick-read banner shows the lowest route sample and the sampled route range. Airport cards and en-route weather rows show their own point value when available; if the source returns no value for a point, the UI says so explicitly instead of estimating one.

Briefway does not derive freezing level from surface temperature or a lapse-rate rule. If Open-Meteo is unavailable, that missing coverage is surfaced as an ATTENTION reason.

Briefway pulls the full international SIGMET feed and keeps only the ones whose polygon passes within 100 nm of the actual great-circle route between your airports (not just a bounding box), sorted by where along the route they occur. Hazard types follow the standard SIGMET set - TS · TURB · ICE · MTW · VA · TC · DS · SS - and a SIGMET is flagged SEV or MOD when the source itself qualifies it that way.

Expired SIGMET are always removed, and when you set an ETD/ETA the list is further filtered to your flight window - see flight timing.

The SIGNIFICANT WEATHER CHARTS section is separate from the SIGMET list: SIGMET are structured hazards filtered against your route; these are broad-area forecast images. A SIGWX / SWLL toggle switches between the upper significant-weather charts (high + mid level) and the low-level significant weather (surface-FL100/150).

SIGWX comes from NOAA Aviation Weather Center Fax Charts: the best matching high-level chart and, when available for the route area, a mid-level companion. SWLL shows low-level charts where a source covers the route - for Italy / the central Mediterranean the Italian Air Force (meteoam.it) charts. Where no low-level chart is available, the SWLL view says so.

SIGWX/SWLL charts are not georeferenced overlays. Briefway does not draw chart hazards on the route map, because doing so from static imagery would imply false precision. The exact valid time is printed on the chart image itself; the fullscreen button only enlarges the source image.

The map's GPS JAM toggle overlays areas of reported GPS/GNSS interference along your route, drawn like SIGMET hazard areas. The data is the free daily aggregate from gpsjam.org, which derives each cell's interference ratio from how many aircraft there reported good vs degraded navigation integrity.

Cells are coloured by severity (LOW / MED / HIGH) and are clickable for the percentage of aircraft affected and how many were observed. Only significant cells inside the route area are shown, and the layer is off until you enable it.

This is a crowd-sourced, day-scale picture of where interference has been seen - useful for awareness, not a real-time NOTAM. Always treat official GPS/RAIM NOTAM as authoritative.

Every route field (departure, arrival, alternate) has a ▦ MAP button that opens a picker. Tap near where the field is and you get two choices:

• Use the nearest airport - resolves your tap to the closest airport in the database and fills its ICAO. The dataset includes many small airfields, so this often lands right on the field.
• Use this point- drops a free coordinate as the endpoint, for an airfield with no ICAO code at all. It's shown as a pilot-style waypoint code (e.g. 4132N01401E).

For a free-coordinate endpoint there is no METAR of its own, so weather falls back to the nearest reporting station and NOTAM to the nearest airport, while the route, SIGMET filtering and time estimates all work off the exact coordinates.

There is no free, unified worldwide AIP feed, so Briefway does not fetch or reproduce AIP content. Instead, for every country the route touches it links directly to that country's official AIS/eAIP portal - from a hand-curated registry for the most common destinations, falling back to a worldwide index of national AIS portals, with the free EAD Basic (Eurocontrol) portal added automatically for member states. These are deep links to the authoritative source, not a mirror of it.

The route map is drawn with MapLibre. The base aeronautical layer (airspaces, airports, navaids) is an optional tile overlay from openAIP, proxied through Briefway's server so the API key is never exposed to your browser. Tiles are cached for 24 hours; if no openAIP key is configured, the map still shows the route, NOTAM and SIGMET, just without the aeronautical base layer.

The map auto-fits to the route only when the route itself changes, so background data refreshes never snap your manual zoom/pan back - useful on small phone screens. Optional overlays include GPS jamming areas and your own GPS position.

NOTAM that match a personal alert rule are drawn with an extra custom alert ring, separate from the standard severity colours. The map can also be switched into an edit mode to reshape the route - see editing the route on the map.

The route the briefing is built on is normally the straight great-circle track between your airports. The edit-route button on the map (top-left) switches into an editing mode where you can shape that track with up to 10 intermediate waypoints:

• Add & drag in one gesture - press and hold on the route line and drag: a new waypoint is created under your finger and follows it until you release (works with mouse and touch).
• Move - drag an existing waypoint to reposition it; the route distance preview updates live.
• Rename / remove - tap a waypoint to relabel or delete it. Departure, arrival and alternate markers are shown for reference but cannot be edited.

Editing is a local preview - nothing is re-fetched while you drag. Reset returns to the original track, Cancel leaves edit mode, and only Apply commits: the new track is drawn immediately, then the briefing re-fetches in the background so distance, en-route weather, SIGMET filtering, freezing-level sampling and the time-along-route estimates are recomputed.

An edited route is a briefing trace only - a direct line through your waypoints, not an airway routing or an official flight plan.

The map's locate button uses the browser Geolocation API only after you press it. When permission is granted, Briefway draws a blue position marker and an accuracy circle, then recentres the map on that fix. Pressing again asks the browser for a fresh fix.

Your GPS position is never sent to Briefway's server, never stored in localStorage, and never included in the share link or print output. Geolocation requires a secure browser context in production.

Every external source Briefway calls, what it's used for, and how often it's re-fetched:

Your route history (the last 20 routes you've briefed) and the record used to detect what changed since you last opened a route are stored only in your browser's localStorage. Personal NOTAM alert rules are stored there too. Nothing about your routes or history is sent to Briefway's server beyond the live API calls needed to build the briefing you're looking at.

Snapshots are stored the same way - frozen briefings live in this browser only and are never uploaded. The offline cache is also local: it holds the app shell, tiles you have already loaded and the last response for routes you have viewed, and it deliberately excludes anything tied to your autorouter sign-in.

GPS position is even more temporary: it lives only in page memory while the map is open. It is not persisted, not shared, and not included in any briefing URL.

Briefway is not an official source and does not replace the official pre-flight briefing from the competent AIS for your flight. Always verify NOTAM, weather and airspace information with an authorised source before departure.

NOTAM severity classification and plain-language decoding, runway wind components, and the GPS-interference overlay are best-effort computed aids - they can misclassify non-standard wording or lag reality. The raw NOTAM/METAR/TAF/SIGMET text is always shown next to the decoded version so you can verify it yourself.

When a data source is unconfigured or temporarily unreachable, Briefway shows that explicitly rather than silently displaying an empty result - but the absence of that notice is not a guarantee of completeness from the upstream source itself.