A medical evacuation of a Philippine Navy sailor from the BRP Sierra Madre at Ayungin, also known as Second Thomas Shoal, was delayed by more than 10 hours. Officials said the China Coast Guard blocked the Philippine vessels sent out to respond to the emergency. Retired Rear Adm. Roy Vincent Trinidad of the Armed Forces of the Philippines gave details of the incident on Friday. The BRP Sierra Madre, a grounded warship, has long been used by Philippine forces as an outpost, with a small detachment stationed on board. The shoal sits in waters claimed by both Manila and Beijing and has seen repeated confrontations between vessels of the two countries. Evacuations from the outpost depend on maritime missions that China has frequently shadowed or obstructed. The delay adds a humanitarian dimension to an already drawn-out maritime dispute between the two neighbors.