Don’t Let Satellite Weather Get You Down

The radar depictions you see from the SiriusXM broadcast are highly filtered to provide only real precipitation areas. Ground clutter, anomalous propagation, birds, insects and such are carefully removed to provide the cleanest and most representative image. But like any process, there will be times where non-precipitation returns do not get filtered out. More importantly, you may see real areas of precipitation filtered out as well.

While rare, the latter usually occurs in regions where WSI (the weather provider for SiriusXM) implements what is called a manual gross filter. This kind of filter is the most efficient way to eliminate any clutter in large areas that are not expected to see precipitation. But when that filter is left on too long, it’ll be just as efficient at removing real precipitation from the broadcast.

zoomed-in-gross-filter

Lightning and a single hail storm attribute marker with no radar depicted.

Here’s one such example depicted above. While connected to the SXAR1 I panned the map over Texas and I saw some lightning and a lone hail attribute marker showing echo tops at 45,000 feet in north-central Texas, but no radar returns. Hmmm?

I verified that I had the Radar Composite turned on (I did) and zoomed the display out as shown below to see that there are plenty of other precipitation areas shown to the northeast and southeast of this area. Given that the area wasn’t cross-hatched with “Radar not available” why wasn’t there any precipitation shown?

texas-gross-filter

Zoomed out to show the presence of other precipitation on the radar composite.

About 15 minutes later I came back to the map to see if there was any change. Notice below that plenty of lightning and storm attributes are being depicted here in north-central Texas; however, there are still no radar returns being rendered. Given this activity, you’d expect there to be some precipitation shown when both lightning and storm tracks are present. This is a classic indication that the real precipitation in this region was being erroneously filtered.

gross-filter

This is a classic signature for a gross filter being left on too long. With the radar composite on, no precipitation is being shown despite the presence of lightning and storm tracks.

Just five minutes later, the gross filter was removed by WSI and the returns suddenly popped into existence as you can see below.

gross-filter-pulled

Once the gross filter was removed, the NEXRAD returns associated with these thunderstorms were rendered.

I took a look at the NEXRAD archives and discovered that the first precipitation developed in this region around 12:05 p.m. CDT. The gross filter wasn’t removed until 12:50 p.m. CDT. That’s 45 minutes with no radar for this area of rapidly developing and potentially severe thunderstorms. Moral of the story is to always have lightning ON and be sure the SiriusXM Storm Markers are also set to ON in the Maps Settings menu (the gear button on the Maps view). Having both of these layers on will likely expose these kinds of uncommon events.

Getting The Lowdown On ForeFlight Radar

In the pilot world there is a ubiquitous debate that continues to thrive over what ground-based radar product is better to use – NEXRAD composite reflectivity or NEXRAD base reflectivity from the lowest elevation angle. Without question, both of these radar mosaics provide a high glance value to the pilot to highlight the location and movement of the truly nasty adverse weather along your proposed route assuming you understand each of their inherent limitations. Now in ForeFlight Mobile 7.7, you’ll have the opportunity to wrangle over which is best since we’ve added a high resolution base reflectivity layer from the lowest elevation angle to complement the current composite reflectivity layer within the app.

But wait…there’s more! In addition to this new layer, we now offer two new low resolution NEXRAD mosaics, namely, a composite reflectivity and lowest elevation angle base reflectivity layer. These two four-color ground-based radar mosaics comply with the dBZ-to-color mapping standards defined by the Radio Technical Commission for Aeronautics (RTCA) documented in Table 3.2 of DO-267A. More on these later.

Radar-Selection

You can now select from one of two radar mosaic depictions in ForeFlight Mobile. The selections include Composite reflectivity and reflectivity from the lowest elevation angle or Lowest Tilt.

Base does NOT equal lowest

First, let’s squash a misnomer about base reflectivity. Many pilots (and even weather professionals) may use the term “base” in base reflectivity to imply lowest. That’s not what it means. In fact, every elevation angle generated by the WSR-88D NEXRAD Doppler radars has a base reflectivity product. The amount of energy directed back to the radar is measured and recorded in a logarithmic scale called decibels of Z (abbreviated dBZ), where Z is the reflectivity parameter. Next, these base data returns are processed by a radar product generator (RPG) to produce hundreds of meteorological and hydrological products including a few near and dear to pilots such as reflectivity.

A more accurate description would be to prefix the product with the elevation angle such as “0.5 degree base reflectivity.” Nevertheless, you may see labels like “Composite Reflectivity” and “Base Reflectivity” on various public and subscription-based websites including those from NOAA. It’s likely that the base reflectivity is from the lowest elevation angle (or lowest tilt) of NEXRAD radar. That’s because the lowest elevation sweep is most representative of precipitation that is reaching the surface which is helpful to the average person on the street including hikers, golfers, boaters and anyone else who wants to know if they need to take the umbrella to work. Unfortunately, the elevation angle is usually dropped (likely due to ignorance or brevity) from these labels.

CompositevsBase-Animation

This is an animated comparison of the composite reflectivity and lowest elevation angle for convection in Florida. Notice the composite reflectivity provides a larger footprint since it picks up on the ice crystals that make up the cirrus anvil.

You might be surprised to learn that in many locations across the U.S., the composite reflectivity image you study before or during a flight is largely made up of only three or four of the lowest 14 elevation scans of the radar.  So in these areas the composite reflectivity and base reflectivity from the lowest elevation angle are not all that different. These areas include regions where the NEXRAD coverage is sparse. Which surprisingly doesn’t only occur in the western U.S. Places such as my home town of Charlotte, North Carolina have distinct gaps in radar coverage.

Radar to the max

Each NEXRAD radar makes multiple 360° azimuthal sweeps at increasing elevation angles from 0.5° to 19.5° depending on the current mode of operation. The number of elevation angles (or tilts) depends on the scanning strategy or Volume Coverage Pattern (VCP) of the individual radar which is set by the radar operator that is located at the local weather forecast office that monitors and manages that particular radar site. A composite reflectivity image considers the base reflectivity from all of the most recent sweeps at each elevation angle and shows only the maximum reflected energy in the vertical column above each location within the radar’s effective coverage area.

It’s all about range

With respect to ground-based radar, range or distance is the key.  Even though the lowest elevation angle is only 0.5°, at 124 nautical miles away the center of the radar beam is already nearly 17,000 feet above the surface due to the curvature of the earth.  So it is easy to see how the higher elevation angles may easily overshoot precipitation that is not in the immediate vicinity of a radar site. Moreover, even if the beam is low enough to see the storm, it may still overshoot the precipitation core.  Let’s take a look at an example.

Below is a two-image animation from the NEXRAD located at the Greenville-Spartanburg Weather Forecast Office in Greer, South Carolina. This shows the returns received from the lowest elevation angle or lowest tilt of the radar which is 0.5° and the fourth elevation angle which is only 1.7° (remember that 19.5° is the maximum elevation). Notice the radar at the lowest elevation has identified an area of weather over Fayetteville, North Carolina (seen on the far right). This cell is approximately 150 miles away from the radar site in Greer (on the far left). However, given it’s distance from the radar, the 1.7° elevation scan completely overshoots this area of precipitation. That means the composite reflectivity image in the Fayetteville area is likely made up of only the lowest three elevation angles of the radar. The remaining higher 11 elevation angles overshoot the precipitation in this region.

Angles

This two-image animation from WDT’s RadarScope app shows the base reflectivity from the 0.5 degree and 1.7 degree elevations. The NEXRAD radar producing this image is located in Greer, SC on the far left. Notice that some returns farther from the radar completely disappear as the radar beam overshoots the weather entirely.

Now it’s true that other adjacent radars such as the one from Raleigh Durham, North Carolina might be able to see this area of weather at higher elevation angles. However, due to the curvature of the earth, the radar beam from the highest elevation angles often overshoots much of the precipitation out there unless it is close to the radar site. This means that locations where there is little overlap between adjacent radars, expect the composite reflectivity image to be very similar to the base reflectivity image for the lowest elevation angle in these gaps.

The four-color radar

If you are flying with airborne radar, you may want to look at the new low resolution four-color NEXRAD mosaic now available in ForeFlight Mobile. The colors depicted in this radar mosaic match the standard color-to-dBZ mapping defined by the RTCA as documented in Section 3.8.2 (Table 3-2) of RTCA DO-267A (shown below). This standard is also used for airborne radar displays.

RTCA radar

This is Table 3.2 of DO-267A that defines the color-to-dBZ mapping for airborne radar.

To see the four-color radar depiction, simply select one of the two radar layers on the Map view. Then tap the gear button next to the Map mode button and scroll down the Settings window until you see the setting switch labeled Four-color Radar just above the Radar Opacity slider. Tapping on the right side of this switch will change the radar depiction from the high resolution radar mosaic to the four-color mosaic. You can also find this four-color switch in the general Map View settings.

4-color setting

The four-color radar switch is located in the general Map View settings or can be found under the gear button at the top of the Map view.

If you use the Stratus (FIS-B) to receive weather while in flight, you won’t find the capability to select the lowest tilt, but you will find the four-color radar will also be available for the composite reflectivity mosaic. As you can see below, the four-color radar mosaic (second image) provides a much more ominous depiction of the weather as compared to its higher resolution counterpart (first image).

Stratus-High-Res

Normal resolution radar mosaic from FIS-B (Stratus).

Stratus-4-color

Four-color radar mosaic from FIS-B (Stratus).

The reason for this may not be obvious. The data broadcast for FIS-B radar does not specifically include the raw dBZ values. Instead it uses intensity encoded values or “bins” that map to dBZ ranges as shown in the table below. Notice the wide 10 dBZ ranges for intensity encoded values of 2 and 3. Based on the RTCA standard defined in the table above, these are mapped in the ForeFlight four-color radar to green and yellow, respectively. Red is mapped to intensity encoded values of 4 and 5 with magenta mapped to 6 and 7. Because of the wide ranges as they map to the RTCA standards, the four-color radar depiction from FIS-B will use much “warmer” colors than the standard depiction.

Intensity-To-dBZ-Mapping

This table from RTCA DO-358 defines the intensity-to-dBZ mapping for FIS-B radar broadcasts. The intensity encoded values of 0 and 1 are considered background and are not displayed as a color. ForeFlight chose to use magenta for intensity encoded values of 7.

Keep in mind that the four-color radar mosaic is a low resolution depiction and will not emphasize storm characteristics like you may see with the Internet radar. This is especially true for the initial evolution of convective cells.

Pilot Reports Get A Facelift

Pilot weather reports are the eyes of the skies. They are not only consumed by pilots, but they are critical data for meteorologists as discussed in this earlier blog post.  For example, SIGMETs for turbulence and icing often live and die by pilot reports. It’s rare to see a SIGMET issued for severe or extreme turbulence until pilots begin to report those conditions. As such they are an important part of any preflight briefing and are even more valuable as they trickle in over ADS-B while en route. That’s why we’ve given pilot report symbols used in ForeFlight a much needed facelift.

ForeFlight PIREPs

The new ForeFlight pilot weather report symbols help to quickly identify adverse weather along your proposed route of flight.

The hunt is over

In ForeFlight Mobile 7.5.2, we’ve significantly enhanced the way you see pilot weather reports displayed in the Map view. Prior to this release, pilot reports were loosely organized into three types, namely, turbulence, icing and sky & weather – each represented by a single pilot report symbol (chevron, snowflake and eyeball, respectively). However, this required you to tap on each and every PIREP marker to see important details such as altitude and intensity. Moreover, routine (UA) and urgent (UUA) pilot reports looked exactly the same. Now, standard pilot report symbology used in this release makes it clear as to the type of report, intensity, altitude (when known) and whether or not it’s an urgent pilot report without the need to tap on the pilot report symbol. So the hunt is over; with the added glance value, the truly nasty weather conditions reported by pilots jumps right out of the glass.

The good, the bad and the ugly

Pilots can include all sorts of things in a report, like seeing a flock of geese or even critters camping out on the runway. But reports of adverse weather (or lack thereof) of turbulence and icing are typically made through a subjective estimate of intensity. In order to enhance the glance value and minimize taps to get information, ForeFlight now uses standard pilot report symbols for turbulence and icing reports. Reports that do not contain turbulence or icing details are defaulted to use the legacy sky & weather “eyeball” symbol. These may contain reports of precipitation, cloud bases and cloud tops as well as outside air temperature and winds aloft (speed and direction).

New Icing PIREP Symbols New Turbulence PIREP Symbols

Each icing and turbulence pilot weather report is shown in the ForeFlight Map view with one of the symbols above that depict the reported intensity.  From left to right, the top row includes icing intensities of null (negative), light, moderate and severe. Also from left to right, the bottom row includes turbulence intensities of null (negative), light, moderate, severe and extreme.

Some intensity reports are “rounded up” to minimize the overall number of icons to remember. For example, you may notice in the symbols above that ForeFlight doesn’t use the official symbol for trace icing. Consequently, a report of trace icing is rounded up to use the light icing symbol. Similarly, we’re not providing a symbol for reports that straddle two intensities such as “moderate to severe.” Therefore, a “light to moderate” turbulence report will be rounded up to use the moderate turbulence symbol; a report of “moderate to severe” turbulence will be rounded up to use the severe turbulence symbol and so on.

Urgent-Report

All urgent pilot reports and reports of a severe nature will be tagged with a red badge to add increased glance value to those reports. For example, shown here is an urgent pilot weather report for severe turbulence at 8,000 ft MSL in the Florida Panhandle.

Above and beyond the different turbulence and icing symbols and to further attract your attention, urgent pilot reports in ForeFlight contain a red badge in the upper-right corner like the turbulence report shown above. These badges will typically be included on a turbulence or icing symbol for a report for severe or extreme turbulence and/or severe icing, respectively.

However, you may also see a red badge included with a weather & sky report like the one shown below. This is typically an urgent pilot report for low-level wind shear (LLWS) or mountain wave activity that did not also include any turbulence or icing details. Also, reports of hail, tornadoes, waterspouts or funnel clouds will be classified and tagged as urgent.

Sky & Weather Urgent

A red badge on a sky & weather (eyeball symbol) pilot report means that the report was tagged as urgent even though no icing or turbulence details were provided. Most of the time this means that low-level wind shear or mountain wave activity was reported by the pilot.

Altitude at a glance

If the pilot report contains a flight level (MSL altitude), this flight level is displayed below the symbol using three digits. For example, from the icing pilot report shown below, 057 is added below the symbol which identifies the reported altitude of 5,700 feet MSL.

PIREP Altitude

A light icing pilot weather report at 5,700 feet MSL (FL057).

On the other hand, when the flight level is unknown (FLUNKN) as it is in the icing pilot report below, we will just show the appropriate symbol (turbulence, icing or sky & weather) without an altitude. Even so, there may be specific altitudes reported, but you’ll have to tap on the pilot report marker to examine the raw report for those details. In this case, light rime ice was reported between 6,000 and 4,500 feet MSL, for example.

No Altitude PIREP

Flight level in this light icing report is unknown (FLUNKN). Tapping on the report reveals more details.

I see double

If the pilot reported both icing and turbulence in the same report, you will see a pair of symbols side by side like the ones shown below with the center of the symbol pair representing the actual location of the report. This pair of report symbols indicates light icing and light turbulence at 16,000 feet MSL.

Pair Of Symbols

A pair of reports means that both icing and turbulence details were provided for the altitude shown in the marker.

Spreading the wealth

To keep everything consistent you will also see these standard symbols show up when tapping on the Map with the AIR/SIGMET/CWAs layer displayed. AIRMETs for turbulence and icing are displayed with their respective moderate symbol and SIGMETs for turbulence and icing will be displayed with their respective severe symbol. For example, in the list below, it’s very simple now to see that the last item in the popover is a SIGMET for turbulence.

AIRMET/SIGMET Icons

Standard symbology is also used in the display of AIRMETs and SIGMETs for icing and turbulence.

Even though there’s now more information available at first glance, you will still want to examine the details of any relevant pilot reports by tapping on the specific markers. Like anything new, it may take a little while to get used to the new pilot report icons. But we feel that the use of standard symbology is critical for flight safety and these changes will provide less taps and a much higher glance value for determining the location and altitude of the most nasty weather being reported by pilots. Lastly, keep those pilot weather reports coming; they are important for all stakeholders in aviation safety.

 

Weather Without Borders

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.

Entire FIR

When the source of the SIGMET isn’t specific about the exact location of the hazard, the entire FIR may be outlined in red.

Unspecified conditions

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.

Unspecified Conditions

In some cases the type of adverse conditions are not specifically provided by the source government. For those situations, Unspecified Conditions will be shown. You are encouraged to read the raw text for those 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.

AIR-SIGMET-Filters

When the AIR/SIGMET/CWA layer is active, use the buttons at the bottom to hide or display the advisories by hazard type.

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.

Volcanic-Ash-SIGMET

Not all hazards can be filtered. These include volcanic ash, radioactive cloud and tropical cyclone advisories.

Prog Charts Are Changing

The Prog Charts that pilots have been using for the last decade or two (pictured below) will be undergoing a facelift sometime in September 2015.

Old-Progs

So at ForeFlight we’re giving you the opportunity to test drive the new charts before they become operational and are officially released by the National Weather Service (NWS). We’ve added these forecasts to our USA Ensemble Imagery and you can find them under the NDFD Progs collection as shown below.

NDFD-Progs

So What’s Changing?

The current Prog Charts are issued by highly experienced meteorologists at the Weather Prediction Center (WPC) in College Park, Maryland; that won’t change. The new implementation will still use the fronts and sea level pressure (SLP) forecast issued by those same meteorologists at the WPC, however, the precipitation forecast represented by those pale green lines is being replaced. The new instantaneous precipitation forecast is now being extracted from the National Digital Forecast Database (NDFD). Instead of the green contours, you’ll see the new precipitation forecast as shaded and outlined regions like the ones shown below.

New Prog chart

Example of the new NDFD Progs.

The new NDFD Prog Charts contain a mosaic of digital precipitation forecasts issued from all of the local NWS weather forecast offices (WFOs) throughout the United States working in collaboration with the National Center for Environmental Prediction (NCEP) and WPC. The forecasts depicted combine the familiar WPC forecasts of fronts, isobars and high and low pressure centers with the NDFD depiction of expected weather type and likelihood.

The precipitation presented on the new NDFD Progs is forecast coverage just like its legacy counterpart. So it is valid at the time posted on the chart and not over a period of time. Using a color-coding, the legend in the lower left corner of the image describes the precipitation type or weather expected (rain, snow, mixed, ice and thunderstorm) as well as the likelihood (chance versus likely) that the precipitation will occur.

Precipitation type legend

Definitions for the various weather types depicted on the NDFD Progs.

We know that it’ll take some time to become completely comfortable with the new forecast depiction of precipitation, but give them a try now so you’ll be way ahead of other pilots come September.

ForeFlight for Apple Watch. Coming Soon.

ForeFlight for Apple Watch

Apple Watch is the first product Apple has designed to be worn and represents a new chapter in the relationship pilots have with technology. It brings a fresh opportunity for ForeFlight designers and developers to deliver new experiences that make interacting with ForeFlight Mobile and important flight information easier and more personal. We are excited to share with you this preview of ForeFlight for Apple Watch.

ForeFlight for Apple Watch weather and instruments.

At-a-Glance Weather and Time

With a flick of the wrist, ForeFlight displays nearby flight conditions, as well as local and zulu time using the Apple Watch Glances feature. Know when flight conditions are above minimums and forget having to do local to zulu time conversions in your head!

ADS-B Weather to Your Wrist

With a Stratus on board and connected to iPhone, ADS-B weather is delivered right to ForeFlight for Apple Watch. In flight and on the ground, easily view current METARs for airports in your recents and favorites lists.ForeFlight for Apple Watch Instruments view.

Customizable Flight Instruments

A customizable dashboard of flight instruments helps you keep track of information like ETE, ETA, distance to destination, track, ground speed, GPS altitude, and more. Configure the instrument layout to suit your preferences.

Flight Notifications and Timers

Apple Watch delivers the ForeFlight flight notifications that you are used to, but in a more convenient way. Get a discreet wrist tap as soon as an expected route clearance is issued. Keep tabs on total flight time or timed approaches in the Timers view.

ForeFlight for Apple Watch Timers view.Get Ready

An iPhone 5 or later running iOS 8.2 or higher is required to run ForeFlight for Apple Watch. The iPhone installs supported applications on Apple Watch and manages communications between the devices. Without an iPhone, you cannot install Apple Watch applications at this time.

 

 

Pre-orders begin today and Apple Watch goes on sale April 24th.

ForeFlight for Apple Watch with iPhone.

ForeFlight Lands at 2015 Army Aviation Summit

ForeFlight at Army Aviation Summit.

Team ForeFlight lands in Nashville this week to participate for the first time in the annual Army Aviation Summit. ForeFlight is all about making your flight mission easier,  safer, and more productive. Come by Booth 1902 for a full demonstration of our Military Flight Bag (MFB) electronic flight bag solution.

MFB is your all-in-one app for digital access to charts and maps, weather, route planning, document management, and more. MFB is an enhanced version of ForeFlight Mobile Pro that integrates the global data set of the DAFIF, D-FLIP publications, AQP pages, and geo-referenced D-FLIP terminal procedures, airport diagrams, and enroute charts.

We have extensive MFB deployments in the Army and Army National Guard, United States Air Force, Coast Guard, Navy, and Marine Corps, with major deployments in Air Force Special Operations Command (AFSOC), Air Force Global Strike Command (AFGSC), US Coast Guard, and US Army Operational Support Airlift Agency.

We can help get your electronic flight bag program off the ground! Reach out using the form here or see us in Booth 1902 at the Summit. Let’s get going on your ForeFlight Military Flight Bag deployment!

Learn more at: www.foreflight.com/military

ForeFlight MOS is Now Booming

As icing AIRMETs begin to morph into convective SIGMETs, you’ll be happy to know that ForeFlight Mobile is ready for the upcoming convective season with some enhancements to its Model Output Statistics or MOS forecast. As was announced earlier, MOS provides a TAF-like forecast out to three days for over 2,000 airports in the U.S. and its territories. To help you anticipate convection during your preflight planning, MOS now includes a forecast for thunderstorms over the next three days as shown below.

Thunder-MOS

April Showers

To celebrate the spring thaw, we are taking MOS a step further; in addition to thunderstorm forecasts, ForeFlight’s MOS product now forecasts showery precipitation at the airport as shown below. While rain showers may not seem like a threat to many pilots, it can be a precursor for deep, moist convection or thunderstorms, including embedded thunderstorms. So any forecast for rain or snow showers should get your attention since it means a convective process is anticipated even if natural lightning isn’t likely. Showery precipitation creates a hazardous environment capable of moderate or greater turbulence in those showery clouds. Additionally, a forecast for showers should raise a red flag that a serious threat of airframe ice may exist while flying in visible moisture at a temperature below freezing.

MOS-Showers

Finding MOS in ForeFlight

The MOS forecast is available to all subscribers with ForeFlight Mobile 6.6 or later. To find it in the app, simply select an airport or station from the Maps view. In the pop-over window, tap the Forecast tab at the bottom. Then tap the MOS button and scroll through the next three days to see if those springtime boomers may alter your plans.

Access the MOS forecast in the Maps view by tapping on an airport.

Access the MOS forecast in the Maps view by tapping on an airport.

Icing and Turbulence Products Now Approved for Operational Decisions

If you have ever used the Current and Forecast Icing Products (CIP and FIP) or the Graphical Turbulence Guidance (GTG) product available in ForeFlight or on the Aviation Digital Data Service (ADDS) website, you may have noticed a disclaimer at the top of the image like the one shown below. Essentially, FAA policy prohibited pilots from using this automated guidance to make operational decisions without also consulting the official forecasts, namely, G-AIRMETs and SIGMETs that are issued by meteorologists.

Warning-CIPEffective January 21, 2015 the NWS and the FAA agreed to relax this limitation and quietly removed the disclaimer from the charts. This opens the door for pilots to make safety decisions based on the information contained within this guidance. This is not to say that G-AIRMETs and SIGMETs can be ignored; they still provide valuable guidance to pilots, but may not have a comparable temporal or spatial resolution found in these automated products.

The disclaimer was also confusing to pilots given that G-AIRMETs for icing are issued for widespread moderate non-convective icing whereas the CIP and FIP provides guidance about all icing hazards big or small. In fact, these automated tools often provide a more realistic picture of the icing environment as it evolves.

It is certainly understandable for such a disclaimer to be required when a new weather product is first introduced or is considered experimental, especially if the guidance is automated. However, these icing and turbulence tools have been available to pilots for over a decade, so it’s finally nice to see them lift these restrictions.

 

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.