Flight Rules Thrown Out of the ForeFlight Mobile App

No, we didn’t convince the FAA to change the regulations; however, in ForeFlight Mobile we’ve stopped using the term Flight Rules when referring to weather conditions for an airport. Flight Rules has now been replaced with a more appropriate term, namely, Flight Category which appears as a selection below TFRs. Same useful information, just under a new name.

Flight Category selected in the Map overlay selector

Flight Category overlay is shown selected in the Maps view menu.

Flight rules refers to the regulatory requirements defined in 14 CFR Part 91, Subpart B. These include Visual Flight Rules (VFR), Instrument Flight Rules (IFR) and Special VFR. Although derived from Flight Rules, Flight Category describes the observed or forecast weather conditions at the airport based on the combination of prevailing ground visibility and ceiling. Using a color-coded marker, flight categories include VFR, Marginal VFR (MVFR), IFR and Low IFR (LIFR) as shown below. Although not implemented in ForeFlight, the National Weather Service (NWS) uses a fifth category to represent Very Low IFR (VLIFR) conditions which includes a ceiling less than 200 feet and/or visibility less than 1/2 statute miles.

Flight Category legend.

Flight Category legend used in ForeFlight Mobile.

In the app, you can also display the ceiling and visibility markers separately on the ForeFlight Map. Similar color coding of these markers will occur based on the criteria shown above. For example, ceilings markers are being displayed on the Map below. Notice for Topeka, Kansas,  a marker labeled “26” representing a MVFR ceiling of 2,600 feet so the marker is shown in blue. It is critical to understand that this does not imply that the Flight Category for the airport is MVFR since this marker does not also factor in the reported visibility.

Ceiling marker view.

Ceiling markers do not factor in the reported visibility relative to Flight Category color coding.

In this case, tapping the marker for Topeka as shown below indicates that the surface visibility is reported at 1 statute mile representing an IFR Flight Category. Hence the coded observation is colored red accordingly.  Similarly, when displaying the visibility markers on the Map, the color shown does not also factor in the reported ceiling.

Weather station details in the Maps view.

Tap on the marker to reveal the Flight Category, indicated by the highlighted observation text, when using the Ceiling and Visibility overlays.

Lastly, ceiling markers are unique in that a marker will only be displayed when the observation is reporting a broken, overcast or indefinite ceiling. In other words, if the sky is clear or there are just scattered or few clouds in the report, a marker will not be displayed on the Map.

While the departure from Flight Rules seems pretty subtle, using Flight Category in the ForeFlight Mobile app now matches FAA documentation and other official weather guidance provided by the NWS.