abalanzar

v. weigh, measure the heaviness of (an object, proposition, etc.); balance, make even weight; consider; hurl, throw; impel, urge into action

= careen, swoop.
Ex: The jet ultimately shot up fully vertically -- at which point the wings snapped off and the whole works careened down into the ocean.
Ex: Magpies are very protective of their young and may swoop on intruders if they feel threatened.
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* abalanzarse sobre = lam into, lay into.