Dozens of Continental Airlines flights to the East Coast from Europe have been forced to make unexpected stops in Canada and elsewhere to take on fuel after running into unusually strong headwinds over the Atlantic Ocean.

The stops, which have caused delays and inconvenience for thousands of passengers in recent weeks, are partly the result of a decision by United Continental Holdings Inc., the world's largest airline, to use smaller jets on a growing number of long, trans-Atlantic routes.

United's strategy works when the winds are calm, and it allows the airline to operate less expensive aircraft with fewer cabin-crew members to an array of European cities that wouldn't generate enough traffic to justify larger planes.

But by pushing its international Boeing Co. 757s to nearly the limit of their roughly 4,000-nautical-mile range, United is leaving little room for error when stiff winds increase the amount of fuel the planes' twin engines burn.

Last month, United said, its 169-seat 757s had to stop 43 times to refuel out of nearly 1,100 flights headed to the U.S. A year earlier, there were only 12 unscheduled stops on roughly the same volume of 757 flights.

Such stops are safer than eating into the minimum amount of reserve fuel pilots are required to keep on board, which guarantees that a plane can fly 45 minutes past its destination or alternate landing spot.

The resulting delays can cause passengers to miss connections; require them to be put up at hotels by the airline; and sometimes prompt them to seek compensation for their troubles.

A United spokesman said the company has been offering compensation as a gesture of good will in situations where customers' experiences warrant it.

Remote Canadian fields at Gander and Goose Bay are the primary places to top off the tanks, but United confirmed that some of its 757 jets were also diverted to Iceland; Ireland; Nova Scotia; Albany, N.Y.; and Stewart International Airport, 60 miles north of Manhattan.

"Headwinds returning from Europe are more extreme than we have seen in 10 years," said a United spokeswoman. For the past decade, December headwinds averaged 30 knots, according to United data. But last month, the winds averaged 47 knots, and, on the worst 15 days of the month, 60 knots.

The winds didn't abate this month. In the first eight days of January, United said it made unplanned refueling stops on 14 flights on the six routes most prone to refueling, including four on the Stuttgart-Newark run, four on Paris-Washington Dulles and two each on Stockholm-Newark and Barcelona-Newark. Those routes tend to be nearly as long as the plane's maximum range.

For remote airports such as Goose Bay and Gander, which have been largely bypassed in recent years by jetliners' longer range capabilities, fueling stops can bring in tens of thousands of dollars in landing fees and other revenue a month.

The United spokeswoman said it hasn't substituted larger aircraft on the affected routes because those planes are being used on other parts of the route network of the Chicago-based carrier, which was formed by the 2010 merger of United Airlines and Continental Airlines. According to industry estimates, a nearly full 757, operating with fewer flight attendants, can be more profitable than a larger plane such as the Boeing 767 carrying the same number of passengers but more attendants.

The refueling-stop issues haven't posed any safety hazards, according to government and industry experts. But a Federal Aviation Administration spokeswoman said agency officials are "aware that United aircraft have made more unscheduled fuel stops this year than last year, and we are looking into the issue." Capt. Jay Pierce, chairman of the pilots union representing Continental pilots, said last week that he asked the union's safety officials to look into the matter.

The fluky weather pattern, which AccuWeather.com meteorologist Henry Margusity blames on La Niña, or cooler-than-normal equatorial ocean temperatures in the Pacific, has also created problems for other airlines using single-aisle 757 jets across the Atlantic.

US Airways Group Inc., which uses 757s between Philadelphia and some European cities, said that in December it diverted four of 112 trans-Atlantic flights due to strong headwinds. Three Amsterdam-Philadelphia flights and a flight from Brussels to Philadelphia gassed up in Bangor, Maine, the company said. Early in January, two more had to stop in Bangor. But the carrier, which has a much smaller European route map than United, has some flexibility to switch to Boeing 767 jets, and a spokesman said it tries to do so in the winter.

AMR Corp.'s American Airlines, which serves six European routes with 757s, said it has had "a few" unplanned fuel stops on westbound flights, but it's "not a daily occurrence." Delta Air Lines Inc., which also flies 757s to Europe, said it didn't experience a single diversion due to fuel constraints in December or so far this month.

United's Continental unit -- which relies on 757s to link its Newark, N.J., hub to numerous European destinations -- has been most adversely affected. And recently, Continental began deploying some of its 757s on two traditional United routes out of Dulles -- to Paris and Amsterdam -- that used to be served by larger planes, exposing some westbound fliers to the same diversions that have played havoc with its schedule and reputation.

Jesse Hoy, a TV producer in Los Angeles, was traveling back from Paris with his pregnant wife on Jan. 3 on a Continental plane. Shortly before takeoff, Mr. Hoy said, the pilot said the jet was going to make an unscheduled fuel stop in Gander due to high winds but would try to get passengers to Dulles in time to make connections. Mr. Hoy said the plane landed at 9:50 p.m., the exact time his United flight to Los Angeles was scheduled to take off. The couple didn't make it home for two more days.

The workhorse 757, which entered airline service in 1983 and was produced until 2004, can carry more than 220 passengers in one class. In the U.S., it was initially used for domestic flights, including coast-to-coast trips, and for trips to nearby overseas destinations. But once the FAA in the early 1990s granted airline operators permission to use it on over-water routes, carriers including American, Northwest, US Airways and Continental found the 757 a fuel-effective way to serve cities in Western Europe that had previously been reached with larger, more costly wide-body planes that consume more fuel but have greater range.

Continental's enthusiasm for the 757 came under scrutiny four years ago when federal officials determined the carrier was responsible for nearly two-thirds of all the minimum fuel or fuel-emergency incidents reported annually by airliners landing in Newark. There were minimum fuel issues on 23 flights arriving from Barcelona over the course of a single year. When pilots make those calls, air traffic controllers give them landing priority. The Transportation Department's inspector general didn't find any safety violations, however.