SEATTLE (Reuters) - Boeing Co said it planned to announce on Tuesday a significant airplane order, a deal sources familiar with the matter said would be with Irish budget carrier Ryanair for about 170 planes worth $15 billion at list prices.

Boeing Commercial Airplanes Chief Executive Ray Conner is scheduled to be in New York for the announcement Tuesday morning, Boeing said on Monday.

The sources, speaking last week on the condition of anonymity, said the landmark order was exclusively for the current generation Boeing 737NG jet.

Reuters reported exclusively in late January that Ryanair was closing on a deal for at least 150 current-generation 737NG passenger jets to be completed within weeks.

(Reporting by Alwyn Scott and Tim Hepher; Editing by Bernard Orr)