On 22 Sep 2021, the Republic of Singapore Navy (RSN)'s Formidable-class frigates RSS Steadfast and RSS Supreme conducted a passage exercise (PASSEX) with the People's Liberation Army Navy [PLA(N)]'s Type 052D destroyer Hohhot, Type 054A frigate Huangshan, and Type 903 replenishment ship Luomahu.
Conducted in the southern reaches of the South China Sea within international waters, the PASSEX saw ships from both navies conducting a series of drills employing the Code for Unplanned Encounters at Sea. Aside from communication and manoeuvring exercises, contactless helicopter operations involving a Republic of Singapore Air Force Super Puma helicopter and Huangshan's Z-9 Haitun helicopter were conducted between RSS Steadfast and Luomahu. In addition, RSS Supreme took part in a replenishment-at-sea drill with Luomahu.
