What is the lowest altitude that ATC can assign on a Victor airway?

Answer: A — MEA (Minimum Enroute Altitude)

The lowest altitude that Air Traffic Control (ATC) can assign on a Victor airway is the Minimum Enroute Altitude (MEA). The MEA is the lowest published altitude that ensures adequate navigation signal reception and provides a safe clearance above terrain and obstacles along the airway. By adhering to the MEA, aircraft remain safe from obstructions and can ensure they stay within the navigation coverage area of the airspace. The MEA is defined for each segment of the airway and is critical for ensuring consistent and safe IFR (Instrument Flight Rules) operations. In contrast, Minimum Vectoring Altitude (MVA), Minimum Obstruction Clearance Altitude (MOCA), and Minimum Safe Altitude (MSA) serve different purposes. MVA is used by ATC for providing safe altitude during radar vectoring; MOCA provides obstacle clearance but is often lower than the MEA and may not guarantee navigation signal coverage; and MSA is intended for emergency maneuvering and does not specifically apply to the assigned altitudes along a Victor airway. Thus, the MEA is the definitive altitude that establishes the lowest safe altitude for aircraft navigating along a Victor airway.