When lightning strikes an airplane, it will latch on to an extremity such as the wing tip or the nose of the plane. As the plane proceeds to fly through the lightning flash, an electric circuit is created and the lightning reattaches to the body of the plane. The current of electricity travels through the exterior skin of the plane and exits from another extremity.
Lightning Protection Features in Aircraft
Most aircraft skins are made out of aluminum and it is a conductor of electricity. There cannot be any gaps in its path because the current must remain on the exterior of the aircraft. Inside the aircraft, there are computers and cables and other equipment. All of this must be shielded from the indirect effect of lightning strikes and attached to surge suppressors.
The airplane’s fuel system must be protected from the lightning current because sparking can occur. The fuel tanks must be thick in order to withstand a burn plus all joints and fasteners must be securely fastened. Any gaps in the structure will allow the current to enter and spark an explosion.
The nose cone, known as a radome, contains radar and other flight instruments. Radar cannot function within a conductive enclosure so lightning diverter strips are applied to the outside of the nose cone.
The Crash of Pan American Flight 214
This Boeing 707 was built in 1958 and was named the “Clipper Tradewind” and had logged 15,609 hours, as recorded by the Aviation Safety Network.
On December 8th, 1963, Pan American Flight 214 departed Puerto Rico and arrived in Baltimore at 7:35pm for refueling before proceeding to Philadelphia. It took off for Philadelphia at 8:24 and went into a holding pattern because of high winds.
At 8:58, the plane was struck by lightning and ignited fuel vapors inside the left reserve fuel tank. This triggered explosions in the center and right reserve fuel tanks. The spilled fuel caught fire and forced the separation of the left wing. The plane went out of control and crashed in flames. All 81 passengers were killed.
What Was Learned from the Crash of Pan American Flight 214
In order to avert future aviation disasters, modifications were needed in order to reduce the vulnerability of fuel tanks. All fuel tanks and fuel lines must have their own systems for grounding, shielding and surge protection.
Jet fuel now has additives that reduce the amount of vapor produced. Although vapor is still explosive, the stricter requirements for the protection of fuel systems have eliminated the possibility of electrical currents caused by lightning strikes entering fuel tanks.
If lightning is dangerous, why do pilots fly through thunderstorms?
Most times, planes are re-routed around a storm or are not allowed to take off or land at airports. According to Jack Williams of USA Today, “All thunderstorms, especially small ones can't be avoided. Lightning flashes into the air and to the ground a few miles from the thunderstorm. An airplane flying into a cloud that's built up an electric charge can trigger a lightning stroke even though the cloud isn't producing lightning on its own”.
Related Articles on Airline Disasters:
Crash of Southern Airways Flight 242
Crash of Delta Air Lines Flight 191
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