Definition
In lightning strike protection, the route through an aircraft's structure along which electrical current flows most easily — typically the most conductive metal pathway from the strike entry point to the exit point. Aircraft are designed so this path carries the lightning current safely around the cabin and sensitive systems rather than through them.
Plain English
Electricity always takes the easiest route through whatever it's flowing through. In an aircraft, designers make sure that easiest route runs along the outside skin and structure, not through the people or the avionics inside.
Context Anchor
Seen in discussions of aircraft lightning protection, especially when explaining how metal structure, connected parts, or protective materials help carry lightning current safely through or over the aircraft.
Derivation
A general physics phrase, not aviation-specific. 'Resistance' here means electrical resistance — how strongly a material opposes the flow of current. Electricity, like water, flows most readily where the opposition is lowest. Knowing this helps pilots understand why metal aircraft skins handle lightning well and why composite aircraft need built-in conductive layers to give the current somewhere easy to go.
Why Pilots Care
Knowing this principle helps pilots and designers ensure lightning follows safe external paths instead of damaging critical components.
Grounding Statement
During a strike, electricity may enter at one point on the aircraft and leave at another, with most of it moving along the easiest electrical route available.
Intuition Check
Do not assume “path of least resistance” means the shortest physical path or one single perfect route. It means the easiest electrical route, and lightning current can spread through more than one path.
Example Sentence 1
The aluminium skin of the aircraft provides the path of least resistance, allowing a lightning strike to travel along the outside of the fuselage rather than through the cockpit.
Example Sentence 2
Designers add conductive strips to create a controlled path of least resistance that protects the fuel tanks.