ForeFlight adds wake turbulence alerts

Datalink weather stole the show when portable ADS-B technology debuted over a decade ago, providing pilots with free in-flight weather imagery in mobile apps like ForeFlight. The companion datalink traffic feature took a little longer to reach maturity, requiring your airplane to be equipped with an ADS-B Out transponder to get the full traffic picture.

That limitation is now in the past since nearly every airplane flying in busy and high-altitude airspace is ADS-B out equipped. As a result, midair collisions are down significantly.

In recent years, ForeFlight has made great strides in using this ADS-B traffic data to better alert pilots of potential hazards beyond en-route avoidance. Last year, the app added Traffic on Runway alerts to notify pilots about potential conflicts between aircraft on final approach with another aircraft on the runway. More recently, the app added Traffic on Same Runway alerts to notify a pilot of a potential conflict when taxiing onto a runway for takeoff that is already occupied by another aircraft.

The latest app update includes a new Wake Turbulence alert to inform pilots about a potentially hazardous situation when flying behind the flight path of heavy airplanes.

Alert visualization

First, several requirements must be met before ForeFlight will display a Wake Turbulence alert:

• ForeFlight must be connected to an external ADS-B device (such as a Sentry)
• You must be flying 500′ AGL or higher
• Traffic must be in a larger wake category than ownship
• The predicted time of entering the wake is 30 seconds or less

When the above requirements are met, both visual and aural “Caution Wake Turbulence” alerts are triggered. The alert can be dismissed with a tap or will disappear after 10 seconds if not acknowledged. It will not trigger again for at least one minute.

The visual depiction of the wake provides an aid to situational awareness when approaching wake turbulence. It moves based on the current winds and dissipates over time, eventually disappearing from the map display. The wake will show on the map until it has fully dissipated or 60 seconds have passed since the alert.

The red portion of the wake represents the vertical portion of the wake closest to your ownship altitude. The red area is from 100 feet above to 300 feet below your ownship altitude. Light green portions indicate areas where the wake is either above or below you. This portion will change as the wake descends or ownship altitude changes.

A white intersection line accompanied by two chevrons will display where the predicted flight path will cross the wake turbulence, providing insight into how to maneuver away from the potential threat if the chevrons are in the red area of the wake tail.

How it works

ForeFlight uses the connected ADS-B receiver (like Sentry) to detect your aircraft weight class and nearby traffic by retrieving it from the ADS-B out data packet. This is converted to the ICAO wake turbulence categories for analysis in the app:

Light < 15,500 lbs

Small – 15,500 to 75,000 lbs

Large – 75,000 to 300,000 lbs

Heavy > 300,000 lbs

Based on this data, ForeFlight will only display an alert if the potential traffic threat is in a heavier category than the airplane you are currently flying. So, if you’re flying a Cessna 182, you won’t see an alert for a Cirrus flying in front of you, but you will see an alert for a Boeing 737 up ahead.

To make this alert more accurate, the app gathers current wind data from a connected ADS-B/SiriusXM receiver or internet winds aloft data saved during preflight to estimate the potential movement of the wake turbulence.

The Wake Turbulence alert feature requires a Pro subscription or higher.