The subtitles were produced by www.unsv.com, a popular website for learning English.
When Florida Postal Service worker Doug Hughes
landed his homemade gyrocopter on the west lawn of the U.S. Capitol,
in a daring bid to deliver a political message to the lawmakers,
the security services were taken by surprise.
He was quickly surrounded and taken away by police,
his aircraft was checked for explosives, and now he faces several years of prison.
But his stunt highlighted once more
that the airspace around most of the public buildings
is easily penetrated by drones and light piloted aircraft,
too small and flying too low to be safely prevented from reaching their goals.
John Hansman a professor of Aeronautics and Astronautics
at Massachusetts Institute of Technology,
said small, flying vehicles are not easy to detect and stop.
"If you have a very small target, like a gyrocopter,
which doesn't have a very large radar cross-section,
so it's not reflecting much energy back, and it's close to the ground,
you might get some signal coming there,
but you may actually think it's a building or a car moving on the ground, not a helicopter."
Hansman noted that heavy traffic in downtown Washington
makes it even more difficult.
"If you have a complex environment like an area around Washington
where you have lots of other vehicles on the ground,
you have vehicles in the air, and you have something very small like this,
it's actually not that difficult for it to slip through the protection."
The chairman of the American Leadership and Policy Foundation,
David Stuckenberg, is a former military pilot who writes about the airspace security.
Speaking via Skype, he said the present safety systems are inadequate.
"We need to understand that we've been lucky
and as technology increases and as drones proliferate people
will increasingly look at these as weapons of opportunity
or technologies that can be adapted for ill intent."
Stuckenberg said a lot more needs to be done before such systems are in place,
such as conducting thorough analyses and bringing new regulations.