Helicopter Sea Combat Squadron 21
HSC-21 Blackjacks Insignia
Active	1977 - present
Country	United States of America
Branch	United States Navy
Role	Search and Rescue (SAR) Logistical Support Naval Special Warfare (NSW) Anti-Surface Warfare (ASUW) Vertical Replenishment (VERTREP) Medical Evacuation (MEDEVAC)
Garrison/HQ	Naval Air Station North Island
Nickname(s)	Blackjacks
Commanders
Current commander	CDR Dave Ayotte (Sep 2018 – present)
Notable commanders	CDR Anthony Saunders(AUG 2011-DEC 2012) CDR Greg Leland (DEC 2012-OCT 2013) CDR Jack Reardon (OCT 2013-Feb 2015)

Helicopter Sea Combat Squadron 21 (HSC-21), nicknamed "Blackjacks", is an aviation unit of the United States Navy based at Naval Air Station North Island. HSC-21 is made up of five expeditionary detachments that deploy aboard ships including Combat Logistics Force support ships, Hospital Ships and Amphibious Assault ships, among others. HSC-21 flies the Sikorsky MH-60S Seahawk helicopter.

HSC-21 was established as Helicopter Combat Support Squadron 11 (HC-11) "Gunbearers" on 1 October 1977 at Naval Air Station North Island, San Diego, California (United States), to provide logistics support for the units of the United States Pacific Fleet. In April 2005, HC-11 was redesignated HSC-21 "Blackjacks". During Operation Iraqi Freedom HSC-21 had shore base detachment as a part of the 2515th Naval Air Ambulance Detachment, Udari Army Airfield, Kuwait. This detachment closed in Fall 2012.

• History of the United States Navy
• List of United States Navy aircraft squadrons

• HSC-21 Official Website Archived 2008-10-20 at the Wayback Machine

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