What Happens When Lightning Strikes an Aircraft?

One of my most memorable moments on a commercial flight took place just after takeoff from Chicago O’Hare International Airport. It was mid-July, and a summer thunderstorm had the airport struggling to get flights out of the city before the weather worsened. Shortly after takeoff, I peered to the right and my eyes fell to a window just above the wing— dark, swollen clouds sat in the near-distance and lightning bolts illuminated the sky in grey and purple hues. The pilot calmly announced that due to weather we were cleared for an emergency landing in Minneapolis. As frightening as this event might be to everyday passengers, aircraft components are designed to be resistant to lightning damage, strikes to an aircraft are actually quite common, and aviation professionals are well prepared for events of this nature.

Of all reported lightning strikes to an aircraft, 96% occur within a cloud structure between 5,000 ft. and 15,000 ft. (1,524 to 4,572 meters). 70% occur during the presence of rain, and 42% of reported strikes occur with no visible thunderstorms in the area. This is because of the energy storage availability created during precipitation, which can affect aircraft up to 5 miles away from the electrical center of a cloud. Lightning attachment is most common on the wing tips, nose, and rudder, or the aircraft’s leading edges because the air around the edges ionizes and creates a strike opportunity during rainy weather. Airports will analyze these factors and more to determine whether aircraft will be able to clear these parameters and reach a safe altitude and to formulate emergency landing procedures.

In production, there are three main factors that OEMs consider when incorporating lightning redundancy in aircraft components. These include the energy level of a potential strike, vulnerable attachment and exit locations on an aircraft, and the duration of a potential strike. The metal structure of an aircraft is the first defense against a lightning strike. It is designed to resist lightning strikes and provide initial protection from current; it prevents electromagnetic energy from interfering with the array of electrical wiring in an aircraft. Other lightning protection components include wire bundle shields, ground straps, aluminum flame spray coating, coated glass fabric, and more. Operational test procedures and subsequent inspections are conducted on vulnerable components to ensure that an aircraft is equipped for a lightning strike event.

Lighting inspection procedures, both before flight and post-flight, are utilized by technicians. The guidelines referenced for inspection include those set by aircraft maintenance manuals (AMMs) and SAE Aerospace Recommended Practices (ARP) 5414, which outlines vulnerable lightning zones on an aircraft. A technician must have a thorough understanding of how lightning damage might manifest on an aircraft. Because of the various lightning protection measures on an aircraft, a pilot may not be aware that their aircraft experienced a lightning strike, and therefore might not report it on the flight log. If it is known that an aircraft has encountered a lightning strike, a conditional inspection will take place. This inspection is performed to identify lightning strike attachment and exit points and to examine any affected systems.

At ASAP Aviation Hub, owned and operated by ASAP Semiconductor, we can help you find all the airport lightning components you need, new or obsolete. As a premier supplier of parts for the aerospace, civil aviation, and defense industries, we’re always available and ready to help you find all the parts and equipment you need, 24/7x365. For a quick and competitive quote, email us at sales@asapaviationhub.com or call us at +1-269-264-4495.