Southend airport suffered a 99,000 fall in easyJet passengers in the five months to the end of July.
Parent company Stobart Group revealed the shortfall to 410,000 over the same period last year in a trading statement this morning.
However, it voiced confidence in achieving a target of more than 2.5 million passengers a year using the Essex airport by 2018.
Stobart said: “We reported in the AGM statement in June that we are currently working with easyJet to determine the optimum capacity for the routes it currently operates from London Southend airport.
“Stobart Group guided then that this would lead to a short-term fall in passenger numbers over the summer.
“As a result of this process, passenger numbers in the five months to 31 July 2015 decreased by 99,000 year-on-year to 410,000, but revenue per passenger increased.
“Stobart Group’s growing relationship with easyJet, coupled with discussions with other low cost airlines, gives us confidence we will be well placed to announce new routes and achieve our target of welcoming 2.5 million passengers to London Southend airport annually by 2018.”