PACIFIC OCEAN (April 27, 2021) Sailors assigned to the embarked Medical Treatment Facility air department aboard the Military Sealift Command hospital ship USNS Mercy (T-AH 19) tie down an MH-60S Sea hawk helicopter assigned to Air Test and Evaluation (HX) Squadron 21 from Naval Air Station (NAS) Patuxent River, Md., on the ship’s flight deck April 27, 2021. Mercy is underway off the coast of Southern California completing dynamic interface testing, where the ship’s aviation facilities will be evaluated for compatibility with the V-22 Osprey and MH-60 Sea Hawk, and establish launch and recovery windows in adverse weather conditions. Mercy recently returned to homeport in San Diego from a regular overhaul in Portland, Ore., where improvements were made to its flight deck to support multiple aircraft platforms. Mercy must be in a five-day-activation status in order to support missions over the horizon, and be ready, reliable and resilient to support mission commanders. (U.S. Navy photo by Mass Communication Specialist 3rd Class Luke Cunningham)