An Airplane appears in the Elmo's World "Transportation" episode. The airplane boasts that he could go faster than a car, train or boat, and explains how all forms of transportation require someone to operate them.
The Airplane's eyes appear on his windshield. Uniquely, he also has a horn, which sounds like an antique car horn. Planes don't typically have horns, because there's nothing to honk at in mid-air.