Maersk and Hamburg Sud were top performers in May with Maersk Line taking first place. APL kept its No 3 spot, and is the first carrier to have held that position for four consecutive months.
The Mediterranean Shipping Company (MSC) was the worst performer of the 20 carriers surveyed, but it improved the most, posting an eight per cent reliability increase from February.
SeaIntel CEO Lars Jensen said the improvements showed most strongly on east-west trades.
"This might indicate that the lower performance seen in the last couple of months might have been related to the carriers' re-shuffling of networks as they were implementing new alliances," Mr Jensen said. "If that is the case, the new-found improvement in reliability will be good news to the shippers."