Tail strike is what happens when the rear end of an aircraft fuselage hits the ground.
The usual cause is when the aircraft's angle of departure is too steep, although it can also happen during landing.
To avoid damage to the skin of the aircraft, some planes are fitted with tail skids, or tail wheels, which absorb the impact of the strike.
After experiencing a tail strike on take-off the pilot will usually execute a go-around and return to the airport where any damage can be assessed, but not necessarily.
When a Singapore Airlines aircraft experienced a tail strike during take-off from Melbourne Airport in 2016 in strong, gusting winds, air traffic control alerted the pilots.
With no tail strike message displayed on the aircraft's instrumentation, the flight crew carried out a tail-strike checklist, determined the aircraft was structurally intact and continued to Singapore.
Despite accusations of unsafe procedures in the tabloid media, a subsequent investigation by the Australian Transport Safety Bureau found the pilots had acted correctly, deeming the incident "an excellent example of flight crew managing a non-normal operation".