SIGMET and AIRMET Along Your Route
Weather at departure and arrival tells only part of the story. Convective cells, turbulence, and icing can sit halfway between two clear METAR stations. NG ROUTE scans active SIGMET and AIRMET bulletins from aviationweather.gov and highlights any that intersect your planned track. The warnings appear in a dedicated panel below the runway card once a route is calculated.
SIGMET versus AIRMET
SIGMET (Significant Meteorological Information) describes weather hazardous to most aircraft: severe turbulence, severe icing, widespread dust storms, volcanic ash, and convective activity reaching specified criteria. SIGMETs cover larger areas and carry higher severity for airline operations.
AIRMET (Airmen's Meteorological Information) describes weather hazardous to lighter aircraft and VFR traffic: moderate turbulence, moderate icing, sustained surface winds, and obscured mountains. Jets still review AIRMETs because moderate icing or turbulence at lower levels can affect departure and arrival phases.
NG ROUTE groups both types in one list because sim pilots benefit from seeing any hazard that crosses the magenta route line on the map.
What NG ROUTE does technically
When your plan is ready, the planner fetches current international SIGMET polygons in JSON format and tests whether your route path passes through or near those areas. Matching bulletins appear as cards with:
- Hazard type (e.g. convection, turbulence, icing)
- FIR or region identifier when available
- Valid time window in UTC
On the map, affected areas may be shaded so you can see geographic context relative to your waypoints. If no warnings intersect your track, the section stays hidden — no news is good news.
How to use warnings in MSFS or X-Plane
Simulators do not automatically inject SIGMET weather into live weather engines. Treat bulletins as briefing cues, not as guaranteed in-sim conditions:
- Convective SIGMET — consider delaying departure, choosing a different cruise level in live weather, or practicing diversions. In MSFS, live weather may already build thunderstorms nearby; the SIGMET confirms where real-world pilots would be cautious.
- Turbulence — expect ride discomfort; reduce autopilot gain or practice manual attitude corrections. Some pilots add weather presets to match the briefed area for training.
- Icing — turn on de-ice systems in turboprops and jets; avoid prolonged flight in known icing layers without protection. Check if your aircraft add-on models icing realistically.
Timing and validity
SIGMETs and AIRMETs have start and end times in UTC. A warning valid for three hours may expire before you reach that airspace on a long flight — refresh your plan closer to departure in real-time prep sessions, or mentally note that conditions evolve.
NG ROUTE pulls active bulletins at plan creation time. It does not continuously update them while you leave the browser tab open for hours. Rebuild the route if you are briefing a evening flight after leaving the tab open all afternoon.
Relationship to METAR and radar
METAR is an observation at a point (the airport). SIGMET/AIRMET describe areas. The weather radar layer on the NG ROUTE map shows precipitation intensity. Together they answer three questions:
- METAR — Can I take off and land right now?
- Radar — Where is precipitation along my map view?
- SIGMET/AIRMET — Are there hazardous phenomena along my route corridor?
Simulation scenarios worth practicing
When a convective SIGMET crosses your track, fly the route anyway in clear weather first, then repeat with live weather and attempt a deviation around the cell — either visually or by editing waypoints on the NG ROUTE map. When turbulence is flagged, practice maintaining altitude in manual flight with autopilot off.
Limitations
Coverage follows aviationweather.gov international SIGMET feeds. Some regional advisories may use different issuance systems in the real world. NG ROUTE is a planning aid for simulation — not a substitute for official weather briefings before real flights.
Checking SIGMET and AIRMET along your route takes seconds and mirrors what airline crews scan on dispatch paperwork. Make it part of your standard NG ROUTE workflow after every plan generation.