Most pilots are surprised when actual weather conditions don't match their in-cockpit weather displays.
An in-cockpit graphic showing a hazardous thunderstorm might be 5–20 minutes old.
An FAA simulator shows pilots how weather displays can lead them astray.
Having data-linked inflight weather information is a major safety advancement, assuming it is used correctly. Outdated or unnoticed weather information can lead to accidents. To help general aviation pilots understand how easy it is to misread weather information displayed in the cockpit, FAA researchers developed a simulation that demonstrates some of the most dangerous snares.
At the 2018 Sun 'n Fun International Fly-In and Expo in Lakeland, Florida, many pilots who flew the NextGen Weather Technology in the Cockpit (WTIC) Program simulator — known as the Weather Information Latency Demonstrator (WILD) — were surprised when their virtual flight took them into a dangerous thunderstorm or low visibility. Most pilots flying the simulation didn't know about the inaccuracies, latencies, and limitations of weather displays in the cockpit. They also failed to realize how often weather displays do not match what they see outside their cockpit windows.
FAA Human-Factors Engineer Ian Johnson flies the WILD simulator used at air shows, as WTIC Program Manager Gary Pokodner observes.
WTIC is part of the FAA's Aviation Weather Research Program, which works to create enhanced weather forecast products for various hazardous aviation conditions, such as turbulence, thunderstorms, and inflight icing. WTIC researchers are experts on the pitfalls of weather displays in general aviation cockpits. Their main goal is to encourage improvements in how meteorological information is shown, so pilots can consistently and accurately interpret that information, understand its limitations, and use it effectively to avoid bad weather.
WTIC researchers have conducted more than 30 studies and experiments on pilot errors in interpreting weather information or understanding the limitations of weather data. The research team plans to publish minimum weather service guidelines for cockpit instrument designers based on findings from their simulations — experiments where pilots perform certain tasks and assessments. The researchers say well-informed pilots will help encourage the aviation industry to improve cockpit instrument displays. The FAA doesn't focus on any specific brands of instruments or weather information services; it focuses research on the most effective ways to present weather information in the cockpit.
Decisions Made with Old Information
In the WILD simulation, pilots are shown a scenario with a thunderstorm ahead of the aircraft. Next Generation Radar (NEXRAD) is a network of 159 high-resolution weather radars. Areas of heavy rainfall may show locations of thunderstorm cells that can have violent updrafts and downdrafts, lightning, and hail. Cockpit displays of data-linked weather are meant to be used for strategic planning to help fly a wide berth around a line of thunderstorms that can be 100 or more miles ahead. Some pilots make the mistake of trying to navigate through perceived "holes" in the storms that can get dangerously close to the aircraft, especially when considering the weather display's latency. Only onboard weather radar should be considered for such a task; it is the pilot's only source of real-time radar imagery.
"Sometimes another thunderstorm cell can pop up behind the one a pilot is watching, and this can happen in a matter of minutes," said Gary Pokodner, the WTIC program manager.
A cockpit display may show a pilot data-linked information about a thunderstorm that is 5–20 minutes old. Believing he or she still is flying in clear air, a pilot can stumble into a storm that they thought would be 20 minutes away in flying time. Thunderstorms can be embedded in other clouds and difficult to spot out the cockpit window, even in broad daylight. A new thunderstorm cell can develop and grow into a deadly monster in a matter of 5–10 minutes. A pilot could even be inside a storm while the cockpit display shows the aircraft is in the clear.
Information presented in the cockpit is delayed for two reasons. First, when the National Weather Service creates a mosaic of precipitation from NEXRAD, it may take 5–15 minutes to render the data as a graphic. Second, it can take five more minutes for the graphic to reach the cockpit. A timestamp on the image may acknowledge only the delay in sending the image to the cockpit, not the delay involved in composing the mosaic. If general aviation pilots are unaware of that key discrepancy, the consequences can be fatal. Concerned about this problem, the National Transportation Safety Board (NTSB) published a safety alert in 2012 and revised it in 2015.
The WILD simulation was created by Purdue University and Western Michigan University under a grant to the Partnership to Enhance General Aviation Safety, Accessibility, and Sustainability. NTSB and NASA Aviation Safety Reporting System databases were analyzed to guide the creation of WILD scenarios, which are based on actual incidents and accidents.
NextGen weather researchers noted that many pilots who tried the WILD simulation at Sun 'n Fun thought they could watch a storm and anticipate where it would be in 5–10 minutes. What they did not realize was that new thunderstorm cells can form during that time to create hazards in unexpected places.
Another challenge for pilots is judging how soon visibility may start to deteriorate in changing weather conditions. For example, if pilots see clouds ahead but don't have any familiar landmarks to help judge distance, they often don't know how soon they will enter the clouds. The NextGen Weather Program team is also trying to determine if a tool could be developed to help pilots judge distances ahead based on ground reference points.
Watching general aviation pilots use the WILD simulation helped researchers confirm the value of their findings on how information gaps in the cockpit can mislead pilots. This includes everything from the latency problem to whether pilots are more likely to miss a cue about weather changes if the alert display uses a certain color.
FAA weather researchers frequently brief industry experts on findings from related studies. Unfortunately, many general aviation pilots don't appreciate the limitations and imperfections of today's dazzling weather displays in the cockpit. But the WTIC team's research into those issues continues, as does its outreach effort to teach pilots about the latest findings and safety guidance.