By Chris Kahn and Tracy Rucinski

NEW YORK/CHICAGO (Reuters) - U.S. fliers still consider ticket prices the most important factor when choosing a flight, according to a Reuters/Ipsos poll, suggesting two fatal crashes of Boeing Co 737 MAX jets have had little impact on consumer sentiment.

In the public opinion poll released May 15, only about half of U.S. adults say they are familiar with the airplane crashes in Indonesia and Ethiopia that together killed 346 people, and only 43% could identify the Boeing 737 MAX as the aircraft involved.

Most importantly for Boeing in the wake of the crashes, only 3% said that aircraft maker or model number was most important to them when buying a plane ticket. In contrast, 57% said ticket price was most important. The poll has a credibility interval, a measure of precision, of 3 percentage points. For a graphic, click https://tmsnrt.rs/2DTmkpW

To see the full results of the poll, which was conducted online in English throughout the United States and gathered responses from 2,008 adults, click here: https://tmsnrt.rs/2VNbtI7

A Boeing spokesman declined to comment on the Reuters/Ipsos poll, but said the company is "committed to returning the MAX safely to the skies so that pilots, crew, regulators and the traveling public have total confidence in this airplane."

During a call with investors last month, Boeing CEO Dennis Muilenburg said he knows "we have some work to do to earn and re-earn the trust of our customers and the flying public in particular.”

If global regulators clear the jets for flight, the Reuters/Ipsos poll data suggest that carriers likely will not have trouble booking seats on the aircraft.

Boeing's fast-selling 737 MAX airliner was grounded worldwide in March after an Ethiopian Airlines crash, just five months after a similar disaster on a Lion Air flight.

Boeing's stock has fallen about 18% since the March 10 crash, and airlines have warned that the groundings are hitting revenues, and costs, to the tune of hundreds of millions of dollars.

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U.S. President Donald Trump urged Boeing to "rebrand" the 737 MAX with a new name in a April 15 tweet, saying "No product has suffered like this one." That sentiment was echoed in a recent Barclays Investment Bank report that concluded that "a large portion of fliers are likely to avoid 737 MAX for an extended period beyond when the grounding is lifted."

Barclays said it based its findings on a survey of fliers in North American and Europe, though it would not disclose to Reuters the survey methodology or questionnaire. It is unclear how Barclays selected its respondents and how much they were informed of the Boeing crashes before being asked their opinion.

Boeing declined to comment on the Barclays survey.

The Chicago-based manufacturer is the target of investigations and lawsuits, and is in regular discussions with U.S. airlines on how to regain public trust. Half of all U.S. adults say that airlines prioritize profits over passenger safety, nearly identical to the result in the April 2018 poll.

But based on the Reuters/Ipsos poll, even if people were aware of the 737 MAX crashes, that knowledge is not likely to influence their travel decisions. People say they mostly consider ticket price when planning upcoming plane trips, followed by travel time, the number of stops and the carrier.

That does not mean all fliers ignore models, according to Steve Hafner, CEO of travel booking website KAYAK. He said the website has seen significant usage of a plane model filter it introduced after the Ethiopian crash, showing demand from some travelers.

"As the news cycle on this simmers down and it becomes less top of mind for travelers, we've seen filter usage go flat. But that's not to say it won't pick back up once the planes start flying again," Hafner said.

SOUTHWEST STILL ON TOP

In another indication of the limited impact of the 737 MAX crashes on consumer sentiment, the airline with the deepest connection to the Boeing narrowbody, Southwest Airlines Co, remained the most popular carrier in the poll.

Southwest, the world's largest 737 MAX operator with 34 jets and at least 249 more on order, is cancelling 160 daily flights during the peak summer travel season as a result of the MAX grounding, more than rival U.S. carriers.

Still, 21% of respondents picked the low-cost airline as their preferred carrier, up from 19% in a similar Reuters/Ipsos poll that ran in June 2017.

"We don't book the plane, we book the place," said Allen Forrey, a 63-year-old truck driver who did not participate in the poll, after landing at Chicago's Midway airport from Phoenix, Arizona on Southwest.

Other frequent Southwest customers at Midway told Reuters they choose the airline because of its two free bag policy, versus fees charged by competitors, and friendly service.

Southwest said the comments were consistent with feedback it receives and noted that "well less than 1% of customers check their aircraft type traditionally, but we do expect more customers to become aware given the current climate."

To ease any concerns, Southwest said it is providing MAX updates on its website and communicating with passengers on a regular basis.

After Southwest, 14% chose Delta Air Lines, 11% American Airlines Group Inc and 8% United Airlines. Thirty-five percent said they did not have a preferred airline, while the rest selected among JetBlue Airways Corp, Alaska Airlines, Virgin America or ultra low-cost carriers Frontier Airlines and Spirit Airlines Inc.

As for the MAX, even if passengers rank prices as the top factor when buying plane tickets, U.S. pilot and flight attendant groups are demanding guarantees from Boeing that the aircraft is 100% safe before they support its return to service.

"The last thing we want is our flight attendants to be afraid to fly that plane," said Lori Bassani, president of the Association of Professional Flight Attendants.

(Reporting by Chris Kahn in New York and Tracy Rucinski in Chicago; Additional reporting by Eric M. Johnson in Seattle; editing by Chris Sanders and Edward Tobin)