Lightning!

The city perches near the top of Australia, roughly 12 degrees south of the equator on the Timor Sea. A combination of humidity, temperature, ionization and frontal weather presents the area with thunderstorms six months of the year.

Everyone I know who has been through Darwin tells stories about incredible lightning storms, and I've made two trips through Darwin myself under the same conditions. Back in the days when Cessna was cranking out dozens of airplanes a day in the Wichita area, I used to witness violent Kansas storms during domestic ferry flights, but none compared to the sheer violence of Darwin's perpetually wild weather.

I remember standing on the porch outside my hotel room in Darwin one January night at 1 a.m., watching the most amazing light show I had ever seen, multiple slashes of lightning covering the horizon, illuminating muscular cumulonimbus clouds storming across the sky. The display went on until just before sunrise, when the clouds magically dissipated to near-clear conditions.

I was reminded of that time recently by Barry Andrews, a client whose A36TC Bonanza I ferried to Singapore a dozen years ago. During that trip, Barry arrived in Darwin the morning after I flew in from the Solomon Islands, and we departed a day later for the 1,800 nm leg up to Singapore. The forecast had been for reasonable weather most of the way, but by the time we passed Surabaya on the island of Java, we knew we were in for a rough ride.

Fortunately, Barry had radar and a Stormscope installed in his airplane, so we were able to keep tabs on the worst weather as we tracked up the Indonesian chain toward Singapore, lightning flashing in the clouds around us. I don't fly to Indonesia that often, but those who do tell me lightning and thunderstorms are regular occurrences.

Like most pilots smart enough to know better, I don't fly in thunderstorms when I can avoid it. Africa also is infamous for its frequent Cb activity, but we usually have the option of waiting out the weather or diverting if it becomes untenable on the Dark Continent. There have been instances over the ocean (mostly in and around the equatorial ITCZ) when I've been forced to ad-lib for a few hours in ugly atmospherics, simply because there was no other place to go than my destination. In 45 years of flying, I've watched lightning brighten the sky inside my cloud several times, but I've never been hit by it.

In contrast to the tremendous power of lightning (a typical ground strike can carry as much as one billion volts), the consequences of a strike on an aircraft are usually benign, because an aluminum fuselage is an excellent conductor, channeling the energy harmlessly through the aircraft's outer skin. In fact, it's estimated that virtually every commercial airliner is struck at least once a year, and hardly any suffer major consequences to people or systems.

The first known instance of a lightning strike bringing down an airplane was in 1940, when a DC-3 crashed in Lovettsville, Va. Since then, there have been a few other accidents, but very few. One common scenario that can cause a crash is a strike on a mostly empty fuel tank. If the air/fuel mixture approaches the optimum 15 to 1, and an electrical charge penetrates inside the tank, the results can be catastrophic.

Serious lightning accidents are so rare that the last verified instance of a strike causing an accident was in 1976, a Boeing 747 freighter in Spain. (The verdict isn't in yet on the 2009 crash of Air France 447, an Airbus 330, into the South Atlantic off Brazil. As we go to press, the data recorder has been recovered from 13,000 feet of water, but it's not known if there's any usable information on the tape.) Composite airplanes have less natural resistance to lightning damage, and therefore are fitted with an imbedded layer of conductive fibers or metal screening material.

General aviation aircraft aren't immune from lightning strikes, but their exposure is minimal, as they typically operate at lower altitudes and rarely in close proximity to thunderstorms. Also, personal aircraft are usually smaller and less liable to attract or generate lightning. Large corporate aircraft that operate in the airline environment are more likely to suffer damage. I once inspected a Beech Starship in New Mexico that had been severely damaged by a strike, forcing the crew to make an emergency landing at the Albuquerque Sunport.

Back in the 1970s, NASA conducted in-flight tests to study the effects of lightning strikes on aircraft. The research team from the NASA Storm Hazards Project flew into more than 1,500 thunderstorms, and their aircraft were struck by lightning over 700 times, usually with no adverse consequences to the airplane. It's a safe bet they did have to clean up the interior after each flight, however.

Incidentally, let no one infer that I'm suggesting thunderstorms aren't dangerous. All pilots know that they can be killers. It's thunder and lightning that's often more bark than bite. I hope no one concludes that I treat the severe weather associated with Cb activity lightly. In fact, the opposite is closer to the truth. Many of the places I fly have no alternates, so I'm actually more conservative than the average bear. I often don't have the option of landing and waiting for the nastiness to pass, so I often don't even depart when thunderstorms are menacing the route. Other pilots with the option of diverting or landing short may opt to take a look, then change the route or forget the whole idea.

Going into Brisbane, Australia, in a Caravan several years ago, I held for two hours out over the Coral Sea, waiting for violent lightning storms to move west, wondering what I'd do if they didn't. Fortunately, the boomers gradually rolled through the area, and I was able to land before fuel became critical.

Despite its spectacular noise and flash, lightning may not be a major hazard for general aviation aircraft, but avoiding it and the often violent weather that accompanies it is simply good sense.