One of the most common questions that comes from new and training pilots is, “Do airplanes fly in thunderstorms?” The answer isn’t always straightforward, but in most cases, airliners route around dangerous convective weather, and general aviation pilots should plan to avoid thunderstorm penetration altogether. Overall, the airline industry agrees that the safest encounter with a storm is usually the one prevented before takeoff.
Part of the reason for thunderstorm weather planning is that it gives pilots time to identify developing cells, consider another route, adjust the route as needed ahead of the flight, and leave room for a delay if the weather moves faster than expected. That makes storm avoidance as much a decision-making skill as a weather skill.
Why Thunderstorms Demand Respect
Thunderstorms are risky for anyone in the air because they generate several hazards at the same time. Those hazards can be difficult to avoid because they often go well beyond the clouds and lightning. The Federal Aviation Administration’s (FAA) Aviation Weather Handbook (FAA-H-8083-28B) discusses hazards to watch out for, such as severe turbulence, hail, lightning, icing, engine water ingestion, wind shear, and microburst activity.
Pilots also have to consider distance; flying near thunderstorms can be downright dangerous, even if you’re not inside of it, and the speed at which airplanes travel can get you into trouble fast. FAA guidance notes that turbulence may occur as far as 20 miles from a severe storm, while a gust front can travel up to 15 miles ahead of associated precipitation. Hail can also impact objects up to several miles from the storm itself, including into clear air.
Learning about thunderstorm hazards in flight training is important because simply remaining outside a cumulonimbus cloud doesn’t automatically mean an aircraft is safe from the storm’s reach.
Start With Preflight Weather Planning
Strong storm avoidance starts before the airplane takes off. Pilots have to review radar as part of a complete briefing. Then, they should look at METARs and TAFs along the proposed route. SIGMETs and Convective SIGMETs add another view of conditions that could affect the flight.
The FAA encourages pilots to gather all information relevant to a flight and continue reassessing weather as conditions change. And, during preflight planning, pilots should determine where convective weather is located and appears to be moving. From that point, an alternate route, along with a fuel reserve, gives the pilot more room to make decisions without allowing get-there-itis to take over.
Decode the Convective SIGMET
Understanding what a convective SIGMET is helps with diligent pilot planning, which can save a significant amount of trouble in the sky.
According to the FAA Aeronautical Information Manual, Convective SIGMETs may be issued for severe thunderstorms with surface winds of at least 50 knots, hail at least three-quarters of an inch in diameter, lines of thunderstorms, or tornadoes. They’re also issued for embedded thunderstorms and those producing heavy precipitation across at least 40% of the area concerned.
Every Convective SIGMET implies possible severe or greater turbulence. They also imply the possibility of severe icing and low-level wind shear, all of which can greatly impact and endanger an aircraft. Bulletins for the contiguous United States are issued hourly at 55 minutes past the hour, with special bulletins available when necessary.
For a general aviation pilot, a Convective SIGMET along the route deserves serious attention during the go/no-go decision, rather than becoming something to consider after departure.
In-Flight Storm Avoidance
Once you’re in the air, flight planning and storm avoidance don’t stop. Avoid by at least 20 mi any thunderstorm identified as severe or giving an intense, heavy, or extreme radar echo. This is especially true under the anvil of a large cumulonimbus. Such echoes should be separated by at least 40 mi before flying between echoes. Separation distances may be reduced for avoiding weaker echoes.
Some of the most useful storm avoidance techniques pilot training reinforces include the following:
- Don’t fly beneath a thunderstorm or its anvil.
- Keep significant distance from intense radar returns.
- Avoid attempting to thread between closely spaced cells.
- Circumnavigate larger areas when thunderstorm coverage becomes extensive.
- Divert and wait on the ground when a safe path around the weather isn’t available.
The FAA specifically recommends waiting out thunderstorms on the ground when navigating around the area isn’t possible. If you’re already in the sky, circumnavigating the storm is essential whenever possible.
The ADS-B Weather Trap
ADS-B weather radar for thunderstorms provides excellent situational awareness, but datalink weather isn’t a live picture.
The NTSB’s Safety Alert SA-017 explains that the age displayed in the cockpit refers to the mosaic image rather than the age of all weather information inside it. In extreme circumstances, actual NEXRAD latency can differ by up to 20 minutes. AOPA also reports on the NTSB warning.
That’s why FIS-B weather and other datalink products work best for strategic routing. Close-in decisions should rely on appropriate current information. Pilots should use visual cues as well as onboard radar when available.
Common Mistakes That Get Pilots Into Trouble
Most thunderstorm encounters happen because of a breakdown in decision-making that leads to errors such as:
- Letting get-there pressure influence the flight
- Underestimating how quickly a cell may develop
- Treating delayed radar as if it were live
- Allowing the aircraft to get too close before changing course
Recognizing these patterns early gives pilots a chance to interrupt them before their flight path options are cut off.
Decision-Making Is the Real Skill
Good aeronautical decision-making and weather planning means being willing to divert, delay, or cancel a flight when conditions fall outside what’s safe.
That’s where aeronautical decision-making and personal minimums work together. Setting limits before a flight helps remove some of the pressure a pilot might feel when making a call before takeoff. Always remember, no pilot, crew, or passenger has to be anywhere badly enough to trade safety for the schedule.
Practice Before It Counts
Scenario-based training is important as it helps pilots learn about and train with deteriorating weather patterns before seeing them in flight. Students might practice recognizing a developing squall line, choosing an alternate route, delaying a flight, or making an early diversion in simulation environments.
In real life, thunderstorms are unpredictable, but the decision process doesn’t have to be. Using simulations to practice builds stronger judgment and keeps pilots ready to face anything that happens.
Build Thunderstorm Decision-Making Skills With MzeroA
Thunderstorm accidents are usually preventable, as avoidance is a skill that pilots can practice and improve. MzeroA’s Private Pilot Course includes Weather and Textual Weather lessons, along with practical cross-country planning and flight preparation designed to support safer real-world flying.
Prospective and current pilots learning more can explore the Private Pilot Course or contact support@mzeroa.com with questions.
A good pilot is prepared for the worst to make every flight as safe as possible.
Sources
https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap7_section_1.html
https://www.ntsb.gov/Advocacy/safety-alerts/Documents/SA-017.pdf
https://www.aopa.org/news-and-media/all-news/2012/june/25/ntsb-warns-of-in-cockpit-weather-delays