An average of 20 million cloud-to-ground flashes over the continental U.S. are detected on a yearly basis by the lightning detection network.
Several teams of atmospheric scientists at prestigious research universities have been examining trends in the amount of lightning. While there is always variability in the atmosphere’s behavior from year to year, the long-term trend indicates an increase in lightning.
A team of scientists at the Massachusetts Institute of Technology (MIT) led by Yakun Liu used satellite data and land-based lightning detection systems to track the movement of the tiny airborne particles generated by Australia’s “Black Summer” wildfires and measure lightning activity in the region.
The study found that lightning strokes increase considerably, by 73% over land and 270% over ocean, during the wildfire season compared to the same time period the year before. The project, “Lightning Enhancement in Moist Convection With Smoke-Laden Air Advected From Australian Wildfires,” was peer reviewed and published in the scientific journal Geophysical Research Letters in June 2021.
A research team led by David M. Romps of the University of California-Berkeley Department of Earth and Planetary Science with colleagues from the Department of Atmospheric and Environmental Sciences at the State University of New York at Albany investigated the effect of changes in the global climate on the frequency of lightning. Their research, “Projected increase in lightning strikes in the United States due to global warming,” was published in the scientific journal Science in November 2014. Overall, their work predicts a 50% increase in the rate of lightning strikes in the continental U.S. during this century.
Any increase in the frequency of lightning will have serious adverse effects on aviation. The impacts affect pilots and aircraft in the air as well as to aviation workers on ramps and the flow of aircraft into busy airports. It also will have a significant effect on wildfire frequency and severity, which in turn can affect the air quality of many states, as well as place added strain on the wildfire management teams and aircraft used in hostile environments.
More Lightning Strikes To Aircraft
The French Aerospace Lab estimates on average that each airplane in the U.S. commercial fleet is struck by lightning on average every 1,000 flight hours. The damage incurred by these lightning strikes causes approximately $2 billion annually in airline operating costs and passenger delays.
Lightning causes physical damage to the aircraft due to the direct attachment of the lightning channel and conduction of the current. Additional effects include bending, melting, burning, pitting, and/or vaporization of the aircraft structure or components, magnetic pinching, shock wave and overpressure, explosion of fuel vapors, electric shock and flash-blindness, and residual magnetism. It also includes the currents and voltages directly injected in associated wiring and plumbing.
According to Greg Sweers, an associate technical fellow in Boeing’s Lightning/High Intensity Radiated Field Protection program, a single bolt of lightning can contain as much as one million volts or 30,000 amps. The amount and type of damage an airplane experiences when struck by lightning can vary greatly, depending on factors such as the energy level of the strike, the attachment and exit locations, and the duration of the strike.
When lightning strikes commercial airplanes , the result can range from no damage to serious damage that requires extensive repairs that can take the airplane out of service for an extended period of time.
Risk To Airport Personnel
When lightning strikes in the vicinity of an airport, a wide spectrum of people are endangered. This includes baggage handlers, fuel and food suppliers, mechanics, other logistics and maintenance personnel, airline passengers, field maintenance and construction workers. Unfortunately, such strikes have sometimes resulted in fatalities.
Airport ramps provide zero protection from lightning. When a lightning storm passed within five miles of the U.S. Marine Corps Air Station at New River in Jacksonville, North Carolina, on July 11, 2017, workers on the flight line were ordered to leave. Mechanics in an MV-22 Osprey were exiting the aircraft when it was struck by lightning. One of the mechanics was ruled brain dead five days later.
A deplaning airline passenger was killed by lightning on June 25, 2015 at Columbia Metropolitan Airport in West Columbia, South Carolina. A tug driver was towing an aircraft with his headset attached to it when lightning struck the aircraft’s tail, sending the electrical current through the headset and electrocuting the driver.
Even after the “All clear” signal has been given, the risk of lightning strikes can still exist. Work on aircraft at Hurlburt Field, a U.S. Air Force facility in Okaloosa County, Florida, in April 1996 was delayed in one morning due to thunderstorms in the vicinity. At 8:29 a.m., airmen were permitted back onto the ramp. A lightning bolt from a developing thunderstorm stuck at 8:38 a.m., killing one airman and injuring 10 others.
National Oceanic and Atmospheric Administration analysis of lightning injuries data reveals that the threat of lightning casualties is lower when a thunderstorm is directly overhead. The greatest number of lightning casualties happen before a thunderstorm arrives and right after it begins to depart. An important point learned from their analysis is that people do not seek shelter or cease outdoor activities quickly enough to protect themselves from lightning strikes.
Lightning Damages Airport Infrastructure
The electrical energy contained in a single bolt of light is sufficient to damage buildings and unprotected electrical circuits and short-circuit communications systems, resulting in millions of dollars of losses.
Randy Bass, formerly manager of the FAA’s Weather Research Branch, has presented data to the aviation industry titled “Lightning Warnings for Airports.” His presentation included an incident on June 23, 2019 when lightning destroyed the transmission equipment in the terminal radar approach control room at Dallas-Fort Worth International Airport (DFW). Even though the controllers worked feverishly to shift to backup transmitters, the incident delayed 600 aircraft and led to the cancellation of 425 flight at DFW. Nearby at Dallas Love Field, an additional 135 flights were delayed and 65 were cancelled.
On April 23, 2009, lightning struck the tower at Hartsfield-Jackson Atlanta International Airport (ATL). The tower was evacuated for a brief time. Due to storm and wind shear, all arrivals and departures were halted. The estimated direct cost due to the lightning-induced outage was $2.3 million in delay costs and $169,000 in cancellation.
Lightning-induced ramp closures cause notable air traffic impacts on both departures and arrivals. This can cause a ripple effect on air traffic globally. According to Bass, airports with the highest number of flights affected by ramp closures for lightning are: ATL, MCO, MIA, TPA, FLL, DEN, IAH, DFW and ORD. Airports with extensive pushback delays include JFK, LGA, EWR, ORD, MDW, IAD and BWI.
Be aware that this data is skewed toward high-traffic demand airports.An astute reader can infer that nearby airports serving business aircraft will be similarly affected.
In Part 2 of this article, we discuss the impact of increasing lightning on wildfires.
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