Under 18 U.S.C. § 1505, it is a federal crime to obstruct, influence, or impede any pending proceeding before a federal agency or department. The NTSB, as a federal agency, conducts mandatory accident investigations under statutory authority. Providing false statements to NTSB investigators — as Radhakrishnan Karthik Nair is alleged to have done regarding the flushing pump — constitutes obstruction. The DOJ also charged the Synergy entities with obstructing the NTSB proceeding by concealing and fabricating documentation about the vessel's fuel systems. Obstruction charges are distinct from the underlying safety violations and can be prosecuted even when the underlying conduct might not independently constitute a crime.