Embraer SA’s board approved a pause in development of the slow-selling E175-E2 jetliner for another three years, further delaying the aircraft’s market debut.

The Brazilian planemaker plans to resume work following the hiatus, targeting an entry into service between 2027 and 2028, Embraer said Friday in a statement.

The 80-seat aircraft is the smallest of a three-jet family manufactured by Embraer that target airline routes that can’t support a medium-size jet like Boeing Co.’s 737 Max or Airbus SE’s A320neo. The E175-E2 had been slated to debut last year, but its commercial introduction has been postponed repeatedly because of an unusual weight problem.

The jet was designed to replace an earlier Embraer model that is a popular workhorse for regional carriers that feed traffic to Delta Air Lines Inc., American Airlines Group Inc. and United Airlines Holdings Inc. at hub airports.

But sales of the E2 model never took off due to a technicality in contracts for pilots at the larger U.S. airlines. Its bigger, more-efficient Pratt & Whitney engines pushed the plane model’s maximum take-off weight above the contractual limit for jets flown by airline subcontractors—and union leaders have refused to budge on the so-called scope clause.

“As in previous years, the re-programing of activities is associated with the ongoing U.S. mainline scope clause discussions with the pilot unions,” Embraer said in the statement. The industrial giant also cited “current global market conditions” for aviation and interest in the current E175 model in the U.S.