Modex

A modex is a number that is part of the Aircraft Visual Identification System along with the aircraft's tail code. It usually consists of two or three numbers used by the Department of the Navy, U.S. Navy and U.S. Marine Corps aircraft that identify a squadron's mission and a specific aircraft within a squadron. These numbers are painted conspicuously on the aircraft's nose, or on helicopters; sometimes on the aft portion of helicopters fuselage or forward portion of the empennage. Modexes are also painted less conspicuously on other aircraft areas (i.e., fin tip, flaps, etc.). Shore-based aviation units use either two-digit or three-digit modexes, while carrier-based units always use three digits.

In a Carrier air wing (CVW), the first digit of a modex number indicates the squadron an individual aircraft is assigned to in the CVW. Modex numbers in the 1xx and 2xx series are assigned to the CVW's Super Hornet Strike Fighter Squadrons (VFA), which fly either the F/A-18E or F/A-18F Super Hornet. Modex numbers in the 3xx and 4xx series are assigned to the CVW's remaining two VFA squadrons (or, if a Marine Corps squadron is assigned, VMFA), which fly the F/A-18C Hornet. As more USN F/A-18C Hornet squadrons transition to the F/A-18E or F Super Hornet those 3xx and 4xx modexes may also belong to VFA squadrons flying the Super Hornet. All CVWs have four VFA squadrons or three VFA and one VMFA. Some are all Super Hornet E or F squadrons and some are a mix of Hornet C model squadrons and Super Hornet E or F model squadrons.

5xx side numbers are assigned to the Electronic Attack (VAQ) squadron flying the EA-18G Growler.

Modex numbers with the first digit of 6 are assigned to the Airborne Early Warning (VAW) squadron (600-609) flying the E-2C (currently transitioning to the E-2D) Hawkeye, and the Helicopter Sea Combat (HSC) squadron (610 and higher) flying the MH-60S Seahawk helicopter.

7xx modexes are assigned to the Helicopter Maritime Strike (HSM) squadron flying the MH-60R Seahawk helicopter.

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Wikipedia