The mares and stallions of Harmony Aeronautics attend the Royal Opera to get a chance to present the idea of their pony flight harness to the Princesses. Gowns by Rarity of Canterlot. Soarin & Pip’s formal wear by Snips of Ponyville.
From chapters 11, 12, and 13 of my MLP:FiM fan fiction Earth & Sky -> [link]