Airbus will commence flight trials of its A320 fitted with winglets slightly later than planned, but the prototype aircraft will still fly this year, says Tom Williams, the aircraft maker’s executive vice president for programs.

The first flight aircraft is also the first A320 built, MSN1. It has undergone numerous modifications over the years for various flight trials, which has made the latest update more challenging. However, Williams says the certification date for the winglet upgrade—Airbus calls the devices “sharklets”—has not changed, nor has the 2012 entry into service date. Airbus has adjusted flight test plans to make up for the delayed start of flight trials.