Flying is pretty safe. Plane crashes are not that frequent. Part of the reason is the care taken to keep things safe. A FOD Sweeper is used to pick up items on the runway that could cause problems. The planes themselves go through a series of checks at every stop. People are screened as they enter the airport, so some potentially harmful items are kept off the airport.
FOD stands for Foreign objects debris, which could be anything on the runway. Small screws or bolts fall to the ground during maintenance or fall off vehicles. Foreign objects of all kinds can end up on the runway for a variety of reasons. It takes a good FOD sweeper to pick up those small items and that keeps airplanes safe. A small screw or bolt getting sucked into a jet engine could cause serious problems. Nails could potentially damage tires as the plane tries to take off or land.
Equipment like a FOD Sweeper does a good job of keeping the runway clear. The greater danger is in items people try to sneak onboard flights. The Transportation Security Administration was formed at least in part in response to 9-11 as the government tried to make flying more secure. They now screen all passengers and they find unusual things at times. The TSA keeps a blog where it posts things it finds.
In the first half of November alone the TSA screened almost 32 million passengers. The fond 205 firearms in carry on bags. The TSA said 176 of them were loaded, and 72 had a bullet in the chamber. The TSA warns that you could be fined as much as $13,000 for trying to get a firearm through a security checkpoint. There are ways to pack a firearm legally if you travel by air. In the second half of November 153 firearms were found, and 127 of them were loaded.
Firearms and other weapons like knives, or explosives are often found. Even replicas or fake weapons are not allowed. In November agents found a metal sculpture of a frog holding a grenade in carry on baggage, and the owner was arrested.
People have tried to sneak snakes and small animals on to flights. Agents have also confiscated fake body parts, and someone even tried to sneak through a live peacock. A scientist tried to bring a 70-million-year-old Tyrannosaurus from Mongolia to the United States.
There seems to be no limit as to what people will try to sneak onto a plane. TSA agents try to keep dangerous stuff off planes, but even the TSA estimates it catches only about 50 percent of illegal items. A FOD sweeper catches a higher percentage of debris on runways than that, keeping most flights safe.