With ForeFlight Mobile 7.4, SIGMETs issued beyond the U.S. border can now be displayed. These International SIGMETs are advisories that cover a wide range of hazards including convection (thunderstorms), severe turbulence, severe icing, tropical cyclone and volcanic ash just to name a few. In most cases these are displayed on the ForeFlight Map view as polygons similar to the way domestic AIRMETs, SIGMETs and convective SIGMETs are depicted. To help with all of these new advisories, we’ve also added the ability to filter this layer by the type of hazard.
The whole FIR and nothing but the FIR
Unlike advisories issued by forecasters in the U.S., International SIGMETs are not always well defined by the source. Occasionally the origin country may not provide the points that define the advisory area. For those situations, the entire Flight Information Region (FIR) is displayed on the Map as is shown below for a hazard within the Mexican FIR.
Similarly, when tapping on a SIGMET polygon, you may see “Unspecified Conditions” displayed in the title of the popover as shown below. This means the source of the advisory did not specify the details of the type of hazard. While ForeFlight will make an attempt to determine the hazard by parsing the raw text, there’s no guarantee we will be able to make that determination in every case. In these situations it’s strongly encouraged to review the raw text of the SIGMET for the details.
No more clutter
Another feature added to ForeFlight Mobile 7.4 is the ability to filter the AIR/SIGMET/CWAs layer by hazard type. When this layer is displayed, you’ll notice four buttons at the bottom of the Map view labeled Ice, Turb, IFR and TS representing hazards associated with airframe icing, turbulence, IFR conditions and convection, respectively. Tapping on any of these buttons will add or remove advisories for that hazard type from the Map. For example, the Turb, IFR and TS hazards have been filtered with only the Ice hazard displayed as shown below. Please note that these selections are preserved. Therefore, if you’ve removed the layer from the Map or closed the app, the next time you view the AIR/SIGMET/CWAs layer on your device, the hazard selections you made earlier will be restored.
The only hazards that are never filtered are those SIGMETs issued for tropical cyclones, radioactive cloud or volcanic ash like the one shown below. These SIGMETs often persist for days or even weeks at a time once they are issued.