The alleged risks could become catastrophic as the airplanes age.
The Southwest Flight 3695 returned safely to Denver International Airport.
It comes as the industry desperately looks for ways to reduce carbon emissions.
Police were unable to catch the flying objects.
The main attraction is a World War II Mosquito that's been grounded for 70 years.
The Yanks are heading to Central Otago for the Warbirds Over Wānaka International Airshow this Easter.
CEO Dave Calhoun will step down by the end of the year.
It'll use sustainable fuel and needs only a simple packed-dirt or gravel runway to land on.
They could hold crucial data as to why the plane dropped suddenly.
