Answer: There are many observed cases of lightning strikes to aircraft inside or near clouds that had not previously produced natural lightning. Studies show that about 90 percent of the lightning strikes to aircraft are thought to be initiated by the presence of the aircraft itself. The scary statistic, however, is that 40 percent of all discharges involving airborne aircraft occurred in areas where no thunderstorms were reported.

Apollo 12

One of the more famous cases of aircraft-initiated lightning is the Apollo 12 launch at the Kennedy Space Center, Florida, in November 1969. The Saturn V rocket was struck not once but twice on its way into orbit.

According to the 1970 NASA findings, other than these two strikes, there was no other lightning activity reported six hours before or six hours after the launch. At the time of the launch, a cold front was moving south into the launch area. Broken towering cumulus topping out at 23,000 feet with light to moderate rain showers were reported.

Rarely Fatal

Damage to airborne aircraft struck by lightning includes minor pitting or scarring to the aircraft’s skin to complete destruction of the aircraft.

Besides direct damage at the point of entry and/or exit, indirect effects that include the loss of VHF communication, loss of navigation equipment, and loss of instrument panel gauges are also possible.

In 1963, a Pan American Airlines Boeing 707 over Elkton, Maryland, was struck by lightning while in a holding pattern at 5,000 feet. The outermost fuel tank in the left wing exploded causing two other fuel tanks to follow suit. There were no survivors.  

• READ MORE: Does the FAA Punish Pilots for Logbook Mistakes?

It’s certainly true that a catastrophic accident such as this is extremely rare, but lightning strikes to aircraft are more common than you might imagine—most of which are aircraft-initiated strikes.

Based on compiled data it is estimated that in the U.S. a commercial airliner is struck once for every 3,000 hours flown. That’s an equivalent of about one strike each year. 

Melting Level

While aircraft-initiated lightning is still being actively studied, there are a few important characteristics to consider.

Based on the current research, it doesn’t take flying in or near a mature thunderstorm to become the victim of a lightning strike. The mere presence of the aircraft in an environment conducive to an electrical discharge is all that is necessary.

Most of the aircraft-initiated lightning strikes occur when the aircraft is flying at or near the melting level (0 degrees Celsius). The preferred temperatures include a range from plus-3 C to minus-5 C, with the highest number of incidents occurring right at the melting level.  

A few of the strikes down low are the result of an aircraft intercepting a lightning strike in progress. Essentially, this is the case of being in the wrong place at the wrong time.

On the other hand, aircraft-initiated strikes are observed the most are between 3 km and 5 km or 10,000 to 16,000 feet during the warm season. Once again, temperature is a key factor. The melting level that typically occurs is in this same range of altitudes throughout the summer months.  

Low-Topped Convection

In general, natural lightning in deep, moist convection doesn’t form until the tops of the storm build well above the melting level.

For lightning to form, three ingredients must be simultaneously present. These include vapor-born ice crystals, graupel, and supercooled liquid water. If any one of these three is missing in sufficient quantities, natural lightning doesn’t generally occur, but this not to say the cloud is void of all electrical activity—some still remains.    

Therefore, an aircraft-initiated lightning strike typically occurs within local air mass instability within low-topped convection.

Often low-topped convection doesn’t produce natural lightning. The updrafts are rather weak in comparison to those that do produce lightning. Consequently, the updrafts do not carry enough supercooled liquid water into the upper part of the cloud where it is needed. 

• READ MORE: What Are Echo Tops?

Clouds and Precipitation

An overwhelming number of lightning strikes occur within the cloud itself. Only a very small percentage of strikes occur outside of the cloud boundary or below the cloud.

Here’s the key: A very large percentage of the strikes occur within precipitation to include rain, snow, snow grains, ice pellets, and hail. It is not uncommon to find a mixture of these near the melting level. 

Keep Your Distance?

The FAA encourages all pilots to keep a safe distance from an active thunderstorm for obvious reasons.

Unfortunately, this practice alone isn’t quite enough. Even when thunderstorms (natural lightning) are not occurring or expected to occur, an aircraft-initiated lightning strike can still be a risk.

In order to avoid an encounter with lightning, the best advice is to remain in cloud-free air whenever possible, especially when the atmosphere is conditionally unstable and capable of producing marginally deep, moist convection extending well above the melting level.

While it may be difficult, the best advice is to operate outside of areas of precipitation and minimize your time in clouds and precipitation near the melting level.

The post How Can an Aircraft Get Struck by Lightning Without a Close Thunderstorm? appeared first on FLYING Magazine.

NASA’s Ray Heineman, director of flight operations and one of the pilots for the behemoth aircraft, gave FLYING a cockpit tour of the airframe that goes back to the early days of the space race—and is still flying.

According to Heineman, the massive cargo aircraft substantially reduced the time it took to transport large rocket parts from the West Coast to Cape Kennedy in Florida. At the time, the parts had to be loaded on barges to get through the Panama Canal or Gulf of Mexico then loaded onto trucks.

“It often took 18 days,” said Heineman, noting that was too long when you were trying to get a rocket into space.

In 1961, California-based Aero Spaceline Industries highly modified a KC-97 Stratotanker. The giant tanker looked an awful lot like a pregnant fish—at the time, guppies were the aquatic pet of choice in America—and the name Pregnant Guppy was bestowed on the aircraft, which had the greatest cargo capacity of any aircraft ever built. 

The interior of the airplane was 19 feet wide, perfect for carrying the second stage of the Saturn V rocket, which was the backbone of the Apollo program.

“Instead of taking 18 days by barge to get to the cape, the Pregnant Guppy was able to do it in 18 hours,” said Heineman.

Super Guppy Ops

The Super Guppy boasts a cargo area that is 25 feet in diameter and 111 feet long. Chances are, if NASA flies it or sends it into space, it will fit in there.

According to Heineman, the size and shape of the Super Guppy make for some interesting flight characteristics, Although the cockpit resembles that of a KC-97 and is very reminiscent of the Boeing B-29 (the yoke and the rudder pedals in particular), the height of the fuselage gives the pilot a vertical center of gravity as well as a longitudinal one. 

“We have a crosswind component of about 20, and we try to avoid gusts,” he said, adding that this aircraft requires a flight engineer and two pilots. ‘”And the pilots are flying all the time, all the way to the ground.”

Open Wide

The Super Guppy nose is hinged, allowing it to open 110 degrees for ease of loading and unloading oversized cargo. According to NASA specs, a control lock and disconnect system at the fuselage break allows the nose to be opened and closed without disrupting the flight or engine control rigging.

A 10-watt electric motor actuates the hinge, and you have to be careful to park the airplane so it isn’t opening into the wind, according to Heineman, because the nose has so much surface area it is like a sail—and you’d be bucking a headwind.  

“It takes 30 to 40 minutes to open the nose,” he said.

Closing the nose is also done carefully with checklists and double checks to make sure the hinge is secure and all the control cables are functioning normally.

Flying the aircraft is an exercise in patience.

“Like any airplane, you roll into a turn and add rudder and then you wait because that control input has to travel down the cables, the cables stretch, and then the aircraft moves,” Heineman said. “You have to be patient and always keep flying it.”

The Super Guppy is on display at the show center at EAA AirVenture 2023 in Oshkosh, Wisconsin.

The post Inside NASA’s Super Guppy appeared first on FLYING Magazine.