Simplify the following text for a Grade 10 native English-speaking person.
Original: The aircraft had been eliminated from regular-scheduled service in the continental United States in 2006 , when Delta Air Lines withdrew the type , but still sees regular service through North American charter operators such as Sierra Pacific , Pace , SkyKing , Amerijet and others .
Simplified: The aircraft had been eliminated from regular service in the continental United States in 2006 , when Delta Air Lines withdrew the type .