NEW YORK ( TheStreet) -- United Airlines(UAL) - Get Report has apparently not received the memo that says the life of the Boeing(BA) - Get Report 767 is coming to an end.

Rather, United is aggressively updating and reallocating its fleet of 767s, which includes both 35 Boeing 767-300ERs from pre-merger United and 16 767-400s from pre-merger Continental.

Last month, United said it would upgrade 11 of the 767-300ER aircraft, investing in winglets, interior modifications and supplemental maintenance. United had already announced plans to make similar investments in 10 other 767-300ERs.

Last week, United said it would put 767s from both fleets to work on four of its Newark-origination, trans-Atlantic routes now operated with narrow-body Boeing 757s. The first transition to a 767 will take place on Wednesday, when Newark-Barcelona becomes a 767 flight.

Subsequently, 757s will be replaced by 767s on Newark-Berlin on June 4 and on Newark-Hamburg and Newark-Madrid on Oct. 25. 

Andy Buchanan, United managing director of international planning, said the carrier has been planning the change ever since the 2010 merger with Continental.

"As we looked at the network and the fleet, we thought early on that getting larger gauge aircraft into Newark to fly to Europe would satisfy customer demand and also improve our financials," Buchanan said. "But our timing was dictated by fleet availability and by the opportunity cost since we were using those aircraft elsewhere."

United planned the change for two primary reasons. First, the 767s will have more premium seats than the 757. "Because of the power of the Newark hub, a larger percentage of the seats are premium seats," Buchanan said. "Especially in London, that's a very important part of the business for us. Moving to a 767-300 from a 757 with 16 in business first to a 767, we nearly double the number of premium cabin seats while economy remains roughly flat."

The United 767s had two configurations, one with six first-class seats and 26 business seats, the other with 30 business-class seats. Eventually they will all have 30 business-class seats, with 184 seats in coach.

Additionally, United and other carriers have recently faced stronger westerly winds as they cross the Atlantic from Europe to the U.S in the winter. As they fought the wind in the winters of 2011, 2012 and 2014, trans-Atlantic United 757s made dozens of fuel stops, typically in Newfoundland. The 767, because it carriers more fuel, would generally be able to avoid fuel stops.

"It's no secret that the (non-stop) reliability of the 757 has deteriorated over time because the winds aloft during the winter are stronger," Buchanan said. "Fuel stops have been in existence forever, but we've seen the trend worsening over the last few years; we're not the only ones taking fuel stops due to stronger winds.

 "Coming into the past winter we saw an uptick, which made us aware that we cannot continue to do this from a reliability and customer perspective," he said. "So we are identifying a plan to get these 767s into the market."

In general, the flights requiring fuel stops fly from deeper into Europe. Shorter flights, from London or elsewhere in England or Ireland, are not impacted. Currently, United flies 757s from Newark on some or all of its flights to Amsterdam, Barcelona, Belfast, Berlin, Birmingham, Dublin, Edinburgh, Glasgow, Hamburg, Lisbon, Madrid, Manchester, London, Oslo, Paris, Shannon and Stockholm.

A third reason for the change is that 767s provide more cargo capacity than the 757s do. "For cargo, the 767 is a game changer," Buchanan said.

In the 1990s, Continental built the Newark hub, originally envisioned by Frank Lorenzo, into a spectacularly successful trans-Atlantic hub by using narrow-body the 757s to cross the ocean. Much of the credit for the concept went to Glen Hauenstein, now executive vice president at Delta(DAL) - Get Report.

Over time, however, "they had stretched the 757 routes beyond the reliable or efficient range of the aircraft and maybe they also want to add some other secondary markets farther into Europe," said aviation consultant Sandy Rederer.

"United's plan also should be a factor for Boeing and Airbus to consider as they explore development of a 757 replacement aircraft," Rederer said.

"The 737-9 MAX and A321 NEO will be very capable and efficient replacements on most 757 missions and the shorter trans-Atlantic routes," he said. "If fuel prices are projected at $80 a barrel of so over the next couple of decades, the market for a substantially different version of the narrowbodies will be pretty thin. The 757s and 767s will be able to go on for several years and the 787s will impinge on that niche when they become more plentiful."

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.