Type 056(A) has a helipad but not a hangar. They can support helos based on land or bigger ships but don't have their own assigned.I don't think a 055 would be leading a green water SAG for ASW purposes. Most likely it will lead blue water SAGs if it wasn't in carrier escort duty.
Type 054As will lead green and brown water SAGs just fine. We have already seen many pictures to that effect.
YU-11 firing off from a Type 056A. Don't forget a 056A also has its own helicopter. It would most likely engage a submarine with its own assets before calling in for help. These ships also operate in packs of four, so they won't be alone. Type 056A or even Type 053H3 are sometimes seen in support or in lead.
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