MIAMI -

A state certified driving instructor offers his take on a fatal bus crash at Miami International Airport. Police said the driver was lost when he drove into an overpass at the arrivals terminal.

"It's a responsibility to have to do all the time, even more so when you're in an unfamiliar location," said CDL School driving instructor Al Hanley.

Hanley, a state certified driving instructor, teaches students at the CDL School in Miami.

"You're responsibility for lives of people and property," added Hanley.

The driver of the private bus who crashed at Miami International Airport on Saturday had a clean driving record and a commercial driver's license. But witnesses on the bus said he only spoke Spanish.

"The driving exam can be administered by an examiner that speaks that native language, so it is possible," said Hanley.

Drivers with a CDL must know how tall their vehicle is and the state's handbook discusses the danger of hitting overhead objects.

"Eleven-foot-six is 11-foot-6 in any language. It's three numbers next to each other and you know the the significance of it," said Hanley.

No charges have been filed against the driver. Investigators are trying to determine why he did not see the signs that warned him over the height of the overpass.

Four passengers remain in stable condition and one other is in critical condition at Jackson Memorial Hospital. Doctors there credited increased staffing at the Ryder Trauma Center with helping them save lives following the crash.