The new tentative agreement between United Airlines and the Air Line Pilots Association (ALPA) aims to boost flying on mainline aircraft.
It continues to allow a "limited" number of 70- and 76-seat aircraft in the Chicago-based carrier's regional fleet based on a block-hour ratio but is designed to return block-hours to mainline pilots, says the union.
In June, Delta Air Lines completed a similar deal with its pilots that increased the number of 76-seat regional jets by 70 but capped the total number of small jets at 450 in return for adding 88 110-seat Boeing 717-200s to the airline's mainline fleet.
United anticipates that it will have 168 large regional aircraft, including 115 Bombardier CRJ700s, 15 Bombardier Dash 8 Q400s and 38 Embraer 170s, at the end of the year, according to the airline.
The four-year pilots contract covers both United and Continental pilots, and would be the first joint collective bargaining agreement with a labour group at United since its merger with Continental in 2010.
Voting on the tentative agreement begins on 1 December and will conclude on 15 December.
United and ALPA reached an agreement-in-principle in August.