The national Israeli carrier said that it acquired a Boeing 787 Dreamliner in response and will continue improving its fleet, according to i24 News. Dreamliners are cleaner and quieter aircraft than the planes El Al currently operates with.

“These aircraft, which will gradually enter service until 2020, will replace by early 2019 the 747-400 fleet,” El Al said in a statement, i24 reported. “The Dreamliner aircraft will join the new 737-900 aircraft the company has purchased, which are already operating on European routes, making the El Al plane fleet younger and less polluting.”

Heathrow’s “Fly Quiet and Clean League” table listed El Al at the bottom out of 50 airlines that use the airport.

Airlines were rated on a number of categories, including nitrogen oxide emissions and efficient landing approaches.

Rounding out the bottom five were Kuwait Airways, Middle East Airlines, Pakistan International Airlines and Omar Air. At the top from number one to five was British Airways, Aer Lingus, Etihad Airways, Scandinavian Airlines System and Finnair.

The top two U.S. carriers came right after at numbers six and seven with American and United Airlines, respectively.