Depiction in the series
The Lavender Spirit first appears in Sweet and Elite. Rarity, Fancy Pants, Swan Song, Four Step, "Caesar", and Sealed Scroll ride the airship—referred to by Rarity as a "fancy yacht"—during the song Becoming Popular (The Pony Everypony Should Know), Rarity christens the airship for its maiden voyage later on in the song, and a miniature version with a different balloon appears in Rarity's Canterlot Castle suite at the end of the song.
The Lilac Sky first appears in Apple Family Reunion. Wensley, Gala Appleby, and Apple Cinnamon arrive to the reunion at Sweet Apple Acres using the airship, and Aunt and Uncle Orange and Bushel return home using it.
The Lavender Spirit appears in silhouette on a poster in Just for Sidekicks.
My Little Pony: Friends Forever Issue #29 briefly features an airship called the Resplendent Duchess. Rarity and Maud Pie plan to book passage on it to the Crystal Mountain Range, but Buried Treasure beats them there.
The Lavender Spirit and Lilac Sky both appear, and are named, in Gameloft's mobile game, offered as rewards for completing certain character collections. The Lavender Spirit is rewarded for completing the "What's Hot" collection consisting of Fine Line, Lemon Hearts, Night Glider, Peachy Pie, Silver Shill, and Upper Crust. The Lilac Sky is rewarded for completing the "Lifelong Friends" collection consisting of Twilight Sparkle, Lemon Hearts, Twinkleshine, Moondancer, and Minuette.