A Layered Approach In ForeFlight

In addition to all of the other great features introduced in ForeFlight Mobile 6.8, we also enhanced the app to allow more layers to be displayed simultaneously on the Map view. Many of these layers are mutually exclusive of one another. That is, when you select a new layer, it will replace the current layer (if any) that was previously selected.  For instance, the app will not allow the Radar and Satellite layer to be displayed at the same time. Therefore, with the Radar layer on, selecting the Satellite layer will deselect and hide Radar layer.

Having this dependency certainly makes sense when selecting between many of the airport-specific layers such as Flight Category, Temperature and Ceiling just to name a few. That dependency hasn’t changed. However, the Pilot Weather Reports (PIREPs) and Lightning layers are not tied to an airport and can now be overlaid individually or together with any of the other Map layers.

Multiple Overlays on Map View

When viewing the Satellite layer, be sure to select Sky Coverage, PIREPs and Lightning for the most complete picture.

This was primarily done to allow users to select the satellite layer while also displaying Sky Coverage along with Lightning as discussed in this earlier blog post. Adding on the PIREPs layer will provide an even greater situational awareness of the weather occurring at any particular location as shown above. If you were to visit the Aviation Weather Center in Kansas City, Missouri, you will notice on the image below that they also make heavy use of overlays.

AWC Overlay Screen

Forecasters often overlay sky coverage and AIRMETs over the visible satellite image.

But if you really want to go crazy, you can select up to seven layers to be displayed at the same time as shown below.  But let’s not go crazy.

Everything Selected

Adding too many layers can render the Map view unreadable.


Automated Ceiling Reports

Every day pilots use surface observations to make many routine operational decisions before or during any particular flight. For example, as you approach an airport you have been trained to listen to the ground-to-air radio broadcast to determine the preferred landing runway based on the current wind direction. Or even before you are in radio coverage you may have been following the latest FIS-B METAR broadcast received by your Stratus and displayed in the ForeFlight Mobile app. Many of these observations come from automated systems. So it is critical that pilots at all experience levels understand how these systems collect and process the weather data especially those automated ceiling reports.


Listen to the ground-to-air radio broadcast when approaching an airport.

The two primary automated observing systems deployed at many airports throughout the United States includes the Automated Surface Observing System (ASOS) and the Automated Weather Observation System (AWOS). These automated systems like the one shown here consist of a collection of electronic sensors that measure the environment, and then process the data to create an observation once every minute. Even though these automated systems create a completely new observation every minute, they must have adequate sensor samples to develop an accurate observation. In order to provide a representative observation at an airport, the automated hardware must continuously collect the sensor’s real-time data over a period of time. The automated system applies an algorithm to the collected data to extrapolate the weather to cover a wider area.


Get the latest observation from ForeFlight Mobile before departing.

This is especially important when considering the observation for sky cover and cloud base height. When approaching an airport, for example, pilots don’t necessarily want to know what’s happening instantly over the sensor since it may not always be representative of the sky condition throughout the airport’s terminal area. Most importantly, it might vary quite a bit between reports.

Automated systems employ an upward-pointing laser beam ceilometer to determine sky cover and cloud height such as the sensor shown here. The cloud height indicator, for instance, transmits a little over 9,000 pulses in 12 seconds, but it’s not these individual samples that are used for the observation. Instead, this data is collected over a period of 30 minutes before a ceiling or sky cover observation is considered acceptable and broadcast to the pilot. So the ceiling report your see on ForeFlight or the one you hear from the ground-to-air radio broadcast is based on a sampling of 30 minutes of data and not the most recent sensor sample taken.


Automated report in the Airports View in ForeFlight Mobile.

Based on studies, 30 minutes of data provides a fairly reasonable description of sky conditions. This means that the system will detect and process all the clouds (if any) passing over the sensor in the past 30 minutes. To account for the latest sky conditions, the result is biased by counting the last 10 minutes of data twice, a technique referred to as double weighting. Using the last 30 minutes of data in this way will allow the system to determine the height and sky cover included in the surface observation and this becomes a reasonable estimate of the sky conditions that is valid over a three to five statute mile radius around the airport.

Keep in mind that these automated systems have a few important limitations. For instance, automated systems can only report clouds that are below 12,000 feet AGL. This means that an overcast cloud deck at 15,000 feet AGL will be reported as clear. Effectively, a clear sky report from an automated station means the sky is free of clouds below 12,000 feet AGL even though it still may be an overcast day.


Towered airport with a trained observer present.

While many high-impact airports throughout the U.S. still rely on a trained weather observer to construct the routine or special observation (SPECI), automated systems supply them with uniform and objective data for the observation. However, automated systems measure only the weather that passes directly through the sensor array so it is not able to report what’s happening outside the airport’s runway complex. Trained weather observers can certainly augment the observation to add these details such as clouds with bases above 12,000 AGL. By the way, the NWS is looking to extend the capabilities of the ceilometer to automatically report clouds above 12,000 feet, but don’t hold your breath; it may take several years before such a solution becomes available.

Customer Notice: Issue with Apple iOS 8.3 and External Bluetooth GPS Receivers

We have learned of an issue with Apple iOS 8.3 that affects some early model Bluetooth GPS accessories, such as the Dual GPS 150 and Bad Elf Pro. When used with iOS 8.3, position information from these accessories may not be delivered to iOS applications, including ForeFlight Mobile.

Stratus and Bad Elf Pro+ devices are not affected. Our friends at Bad Elf have escalated the issue to Apple for resolution.

As a workaround, customers with Wi-Fi + Cellular iPads who have upgraded to iOS 8.3 can disconnect their Bluetooth accessories and rely on the iPad’s internal GPS or Stratus. Customers with Wi-Fi only iPads who have upgraded to iOS 8.3 will need to wait for a resolution, upgrade to a newer GPS accessory, or connect to a Stratus.

We will keep you updated. If you rely on one of these early model Bluetooth GPS accessories, we do not recommend that you upgrade your Apple devices to iOS 8.3.

Fooling Around With Convective Wind Shear

Most pilots equate wind shear to turbulence or convection. Certainly some forms of wind shear are indeed turbulent and convection can also induce dangerous wind shear. If the wind shear occurs close to the surface when the aircraft is landing or departing, it may be in excess of the inertial capabilities of the aircraft making it difficult for the pilot to recover resulting in an accident that is often fatal. But don’t be fooled; some of the most dangerous wind shear situations come out of rather benign-looking convective environments.

Moist low-level outflow from a thunderstorm.

Moist low-level outflow from a thunderstorm.

Perhaps the most dangerous wind shear occurs in a convective downburst where downdrafts in thunderstorms have been estimated to be greater than 100 miles per hour. These high-speed winds strike the surface and spread out creating a gust front that can also be very dangerous especially if it occurs when landing or departing. When that downburst occurs in a very small area spatially (about 2 miles) it is referred to as a microburst similar to the one in this image. Most microbursts are ephemeral lasting no more than five minutes in most cases.

At this point in time, several large turbojet aircraft have succumb to the forces associated with a microburst. The one that is especially memorable is Delta Airlines Flight 191 that encountered a microburst on approach to the Dallas Fort Worth International Airport (KDFW) in 1985. Delta Flight 191 didn’t fly through or under an intense supercell thunderstorm as you might imagine. In fact, a thunderstorm with a cloud base of nearly 10,000 feet was the culprit. High-base convection with a heavy rain signature should be of particular concern to pilots since they signal a deep mixed layer with a high lapse rate and plenty of precipitation to fuel a strong downdraft. Pilots can be fooled because high-based convection does not seem particularly threatening (especially to pilots flying large turbojet aircraft) which makes them even more likely to stumble into the path of a downburst or microburst.

Here’s a quote from a paper written by Captain William W. Melvin entitled Wind Shear Revisited, Air Line Pilot Magazine, Nov 1994.

Many pilots have been trained to avoid large supercell-type thunderstorms in the belief that this will prevent encounters with microbursts. Yet no evidence exists that any of the known microburst encounters have occurred in supercell storms. Dr. Ted Fujita and Dr. Fernando Caracena recognized authorities in this field have repeatedly emphasized that microbursts are frequently generated from benign-appearing cells. Many “experts” who disagree with Drs. Fujita and Caracena have emphasized the supercell storms with warnings of dangers of gust fronts. These so-called experts are leading pilots down the primrose path for microburst encounters.

In a high-based thunderstorm there’s typically an extremely dry environment between the cloud base and the surface. Initially, little or no rain may reach the surface. As the rain falls out of the cloud into this very dry atmosphere it evaporates quickly which causes a cooling effect relative to the air around the precipitation. Such cooling makes the air much denser, and therefore negatively buoyant, effectively creating a very intense downburst with winds that may exceed hurricane force, even approaching the speeds found in a weak to moderate tornado.

The next time you see what appears to be a very inviting situation in and around active convection, think twice about departing or making that approach to land. Microbursts can happen quickly before any visual cue may exist. Especially avoid areas where you see a circular ring of dust at the surface that may be curled around the edges or any kind of bulge (piling up) of precipitation at the bottom of an evolving rain shaft. These are all characteristics of a intense downdraft, microburst or gust front.

Expanded Taxi Chart Coverage, Taxi Chart Improvements Land in ForeFlight Mobile 6.8

We are pleased to announce that ForeFlight Mobile version 6.8 is now available for download on the App Store! This update focuses on improving airport surface operations with more taxi chart coverage and more information on taxi charts for improved guidance. A new ownship setting makes compliance easy for customers operating under the guidance of FAA AC 120-76C. Version 6.8 also moves the app to a new minimum level of iOS support, paving the way to better product efficiency and more feature capability in the future.

FBOs on Taxi Charts

Taxiing to the FBO just got easier—over 2700 FBO locations are now mapped on both FAA and ForeFlight Airport Diagrams for better ground-based taxi guidance. When coupled with ownship display capability in ForeFlight Mobile Pro, you can easily see where your aircraft is in relation to the FBO. We continue to add more FBO markers with each Business Directory update.

(Edited 4/13/15: ForeFlight Mobile version 6.8.1 is now available on the App Store and resolves the issue where FBO markers were not displaying on ForeFlight Mobile Basic accounts.)

FBOs on Airport Diagram

FBO markers shown on the airport diagram for Houston’s Hobby Airport.

While viewing a taxi chart, tap on any FBO marker to see detailed information, including photos, fuel prices, contact information, and more. FBO markers will appear on taxi charts within the Plates view and also when displaying a taxi chart on top of the moving map.

FBOs on Airport Diagrams detail view.

Tap on the FBO marker to reveal detailed location information.

You can choose to show or hide the FBO markers using the FBO button on the Plates view:

Turn FBO overlay on or off in the Plates view.

Turn FBO overlay on or off in the Plates view.

Or on the Maps view, tap anywhere on the taxi chart to open the pop-over menu and toggle the Show FBOs button ON or OFF:

Turn FBO overlay on or off in the Maps view.

Turn FBO overlay on or off in the Maps view.

If you are an FBO and would like to place your marker, login to your ForeFlight Manage account or contact directory@foreflight.com to set up an account.

FBOs on Airport Diagrams is available to Basic and Pro subscribers; ownship position on geo-referenced airport diagrams is a Pro feature.

Expanded Taxi Chart Coverage

We continue to invest in expanding our taxi chart coverage, providing taxi charts for airports not mapped by the FAA. As of this release, we have added more than 1,700 ForeFlight taxi charts—more than tripling the coverage provided by the FAA alone! Our airport mapping team continues to expand ForeFlight’s library, giving you more coverage at more airports. Combined with the new FBO display on taxi charts, finding FBOs at airports is easier than ever.

Easy Ownship Compliance Support for Operations Under FAA AC 120-76C Guidance

Ownship depiction with runway proximity advisor.

Approval for ownship display on airport diagrams is a huge safety enhancement for Part 135 and 121 operators.

ForeFlight now makes it easier for our certificated FAA Part 91F, 91K, 121, 125 and 135 customers to comply with ownship display limitations as defined in FAA AC 120-76C operational guidance for use of electronic flight bags.

These operators are limited to using ownship depiction during airport surface operations and at less than 80 knots ground speed.

To access the setting, navigate to the More > Settings view, then scroll down to Preferences and tap on Enable Ownship. The ownship setting options include: Always, Never, and Limited. Limited mode automatically applies the speed-restricted display function as described in the Advisory Circular. Once airborne, the ownship display icon is automatically removed from view. 

New ownship setting for easy compliance.

New ‘Limited’ ownship setting makes it easy to comply with FAA AC-120-76C guidance.

If your flight operation is not taking advantage of ownship display on taxi diagrams, we have the tools and resources to help you get going. Email sales@foreflight.com for more information.

ForeFlight 6.8 requires iOS 8 or higher

Please note that ForeFlight Mobile 6.8 requires iOS 8 or higher. By moving to iOS 8 as the minimum supported iOS version, we can deliver new features enabled by the Apple update, deliver smaller application downloads, improve energy efficiency, improve support for devices like the iPhone 6 Plus, and deliver faster application performance. 

If you would like to take advantage of the new features in ForeFlight Mobile 6.8 or later, you will first need to update your device to the current iOS 8.x version. Apple posted this helpful article with instructions on how to update your iOS device to iOS 8.

For those of you running Apple iOS 7.x or earlier versions, you will still be able to use your current version of ForeFlight Mobile. After ForeFlight Mobile 6.8 is released, if you need to reinstall ForeFlight on an existing device you can download the last compatible version of ForeFlight Mobile from the App Store. If you have any questions, please contact us at team@foreflight.com.

The only device that is not capable of upgrading to iOS 8 that is currently also supported by iOS 7 (the current minimum iOS requirement for ForeFlight Mobile) is iPhone 4.

Blue skies!

Density Altitude: The Secret Killer

Now that the warm season is approaching, pilots need to start planning for the secret killer, namely, density altitude. In fact, density altitude (DA) is perhaps just as hazardous as airframe icing. In an NTSB study, density altitude contributed to just as many accidents as icing shown in the pie chart below. To be fair, some of the accidents in the NTSB study that were attributed to density altitude were caused by pilots departing in an over-gross weight aircraft or using improper procedures (e.g., improper flap usage). However, every pilot needs to be aware that gross mistakes such as this are not forgiving when the density altitude is high.


What is Density Altitude?

In simple terms, density altitude is pressure altitude corrected for non-standard temperature. Therefore, if the pressure and temperature throughout the atmosphere matches the standard, then pressure altitude and density altitude are equal. Of course, during the warm season, the temperature is generally above standard in most locations throughout the U.S. creating an invisible hazard if ignored.

If you’ve ever flown out of a high-elevation airport such as Santa Fe, New Mexico (6,348 feet MSL), you have experienced the effect of density altitude. At these airports, the performance of the aircraft decreases. For fixed-wing aircraft you will experience a longer takeoff distance, longer landing rollout and reduced rate of climb. The higher you are above sea level, the lower the pressure and that means the air is less dense. This reduction in air density reduces the wing’s lift and also lowers the efficiency of the propellor or rotor.

What About Temperature?

The temperature of the air can have the same effect even at sea-level airports. As daytime temperatures begin to creep up into the upper 80s and 90s, the air becomes much less dense similar to being at that high-elevation airport. That means there are fewer air molecules in a given volume of airspace. Less air, means poor aircraft performance similar to what was described above. And of course, the combination of high temperatures at high-elevation airports can make for a serious hazard waiting to happen if unchecked.

While a pilot can determine pressure altitude in the cockpit by setting the altimeter to 29.92″, there’s no handy-dandy instrument that you can use to directly measure the density altitude. It must be calculated based on the station’s pressure (not the altimeter setting), temperature and dewpoint temperature. Not to worry, the ForeFlight Mobile app does all of the work for you.

Finding Density Altitude in ForeFlight

To find the density altitude simply select an airport from the Maps view. In the pop-over window, tap the METAR tab at the bottom and scroll down a bit to see the current density altitude for the chosen airport.

Density-AltitudeJust like any other aspect of weather, pilots need to prepare in advance. Before you close the door to the cockpit, double-check the density altitude in ForeFlight to be sure it won’t adversely affect your flight. To learn more about density altitude, please refer to this FAA safety publication.

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

Forecasting for the Terminal Area is Incredibly Difficult

Perhaps the most difficult forecast any meteorologist has to issue is a Terminal Aerodrome Forecast or TAF. They are the most detailed aviation forecast made available to pilots and they will be around for a long time to come. The terminal area is quite small; it is officially defined as “the area within five statute miles of the center of an airport’s runway complex.” Do you remember the world globe you used in grade school?  Well, imagine placing a single dot on that globe with a sharp pencil – that’s about the size of the terminal area. Consequently, forecasters consider a TAF a point forecast.

Let’s take a look at a specific example. Below is a TAF for the Fort Smith Regional Airport (KFSM) issued at 1736 UTC – well before any thunderstorms had formed. Notice the forecaster believes that moderate rain and thunderstorms will temporarily impact the Fort Smith terminal area between 0000 and 0300 UTC (8 p.m. to 11 p.m. EDT).

FSM-TAFIf you had also looked at the automated ForeFlight MOS forecast below within a similar timeframe, you would have seen a much different forecast. In fact, MOS did not forecast any thunderstorms or precipitation from 1900 to 0200 UTC (3 p.m. to 10 p.m. EDT). Instead, MOS predicted some gusty southwest winds with good visibility and a high scattered cloud deck. Which one provides the best guidance?


Actually, both! As it turned out thunderstorms did roll through the terminal area as predicted by the TAF a little bit after 0000 UTC as shown in the METARs below. However, the total amount of precipitation measured in the Fort Smith rain bucket for the event was a meager 3/100 of an inch.  So the primary thunderstorm cell passed through the northern edge of the terminal area with the sun low in the horizon beaming in from the west (notice CLR skies were also reported).

KFSM 250353Z 28005KT 10SM CLR 18/14 A2992 RMK AO2 SLP127  

KFSM 250253Z 27007KT 10SM CLR 19/15 A2990 RMK AO2 SLP122

KFSM 250153Z 26010KT 10SM SCT050 22/15 A2986 RMK AO2 RAE19 TSE33 P0003

KFSM 250139Z 28008KT 10SM FEW038 BKN050 21/16 A2986 RMK AO2 RAE19 TSE33 P0003

KFSM 250053Z 21012KT 10SM -TSRA CLR 24/14 A2982 RMK AO2 RAB49 TSB02 SLP093 LTG ICCC P0000 

KFSM 250008Z 21013KT 10SM TS CLR 26/13 A2980 RMK AO2 TSB02 LTG ICCC 

KFSM 242353Z 21016G21KT 10SM CLR 26/13 A2979 RMK AO2 

KFSM 242253Z 22019G26KT 10SM BKN065 27/12 A2979 RMK AO2

Fort Smith was on the southern-most edge of a fairly broken line of thunderstorms as shown on the ForeFlight Map view below.  This line of storms quickly moved in from the west along and ahead of a surface cold front. As you can see below, there was one small cell that moved through the Fort Smith terminal area approximated by the small red circle. It’s this cell that triggered the thunderstorm observation at 0008 UTC.


So it’s easy to see that Fort Smith could have been in that large gap to the northeast creating a situation more representative of the automated MOS forecast. The forecaster that issued the TAF took a little meteorological risk and felt there was a fairly reasonable chance this line of thunder would evolve and impact the Fort Smith terminal area; a gutsy move given how this broken line of storms ultimately evolved.

MOS, on the other hand, wasn’t as certain about the possibility of thunderstorms passing through the terminal area; it was leaning towards a forecast more representative of the weather within the gap. This is a good example of the “edge effect” that happens quite often when issuing such a point forecast whether it is issued by a meteorologist or automated tool. Ten miles can make a huge difference in making a good forecast or getting it wrong.


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.


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.


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.

Faster, Better Auto-router Now Available and DUATS service deprecated

Last night we released an update to our airway routing suggestion in Route Advisor by replacing our previous route provider, DUATS, with our integration partner Lockheed Martin. This enhancement brings quicker response times and more accurate and direct routing for user-provided origin and destination pairs. 

Lockheed Martin provides proper entries and exits onto and off of the airways so that clicking on the suggested route and loading it as a flight plan should be a seamless process. Previously this was not always the case with DUATS and some routes failed to load properly.

Below is a screenshot of an airway routing between KAXH and KLAL in preparation for our flights to Sun ‘n Fun 2015, as computed by the new router:


In addition to leveraging Lockheed Martin’s routing engine, we implemented server-side caching on routes that will provide an instant response for routes that have been recently searched by other users. Give it a try for some of your favorite routes and let us know about your experience – it is fast! 

We are always working to improve our infrastructure to provide the most utility for your flight planning goals, and this is another great step forward!

DUATS Support Deprecated

With this release, we are also deprecating our support for DUATs based services in favor of the modernized web services technologies provided by Lockheed Martin. For those customers who still have DUATS credentials configured in ForeFlight Mobile, we recommend removing those credentials to take full advantage of the more advanced capabilities.

Sign out instructions are provided on page 153 of the ForeFlight Mobile Pilots guide and as follows:

  1. Tap More > Accounts.
  2. Tap on the “CSC DUATS” field.
  3. Tap the red “Sign Out” button on the next page.

As always, we are on frequency at team@foreflight.com to answer any questions you have.