(Adds statement from SkyWest)
By Marcelo Rochabrun
Jan 30 (Reuters) - Brazilian planemaker Embraer SA said on Thursday that U.S. regional carrier SkyWest Inc has signed a firm order for 20 E175 planes from its E1 generation, worth close to $1 billion, as an order for newer E2 aircraft remains in limbo.
SkyWest ordered 100 next-generation Embraer planes in 2013, but labor negotiations between pilot unions and airlines in the United States - where there are union restrictions on aircraft size - have so far not allowed regional carriers to fly the new plane.
Due to the uncertainty, Embraer in 2018 removed the order for the newer E175-E2 from its backlog, a document where the planemaker lists the number of orders it has received for its various planes.
SkyWest said on Thursday that its order for the E175-E2 was still on its books, but that its execution depended on reaching a new agreement with pilot unions, under a provision called the "scope clause".
The airline added that the order announced on Thursday did not affect the order for the 100 E175-E2 planes.
SkyWest was the launch customer for the broader E2 line in 2013, announcing back then an order worth as much as $9.4 billion.
Embraer executives said at the time that the order was a vote of confidence in the new aircraft line, which has since faced some delays.
Embraer has yet to deliver any E175-E2 jets. Embraer executives have said the planes might have more commercial success outside the United States, where there are fewer pilot union restrictions on size. (Reporting by Marcelo Rochabrun; Editing by Daniel Wallis and Christopher Cushing)