There are various synonyms for the phrase "soar like an airplane". It could be described as "flying high", "taking off", "rising rapidly" or "ascending like a bird". Alternatively, one could say "ascending like a rocket", "rocketing skyward", "shooting up" or "ascending swiftly". Other possible synonyms include "climbing steeply", "surging upwards", "ascending gracefully", "lifting off", "climbing rapidly", and "gliding through the air". No matter which synonym one chooses, the idea is the same: to emphasize a powerful, upward movement, as if one is soaring to great heights like an airplane.