Several airline rankings were released in the past week, and Frontier Airlines didn't do very well in any of them.

The Denver-based airline, which earlier this month filed the paperwork to go public, ranked last in two recent rankings, and didn't appear at all in a third.

In the "2017 Airline Quality Rating" compiled by researchers at Embry-Riddle Aeronautical University and Wichita State University, Frontier finished 12th of 12 airlines ranked, with Alaska Airlines finishing first and Delta finishing second.

"The rating is a multifactor examination of the airlines based on mishandled baggage, consumer complaints, on-time performance and involuntary denied boardings," researchers said in the study, released this week. The good news for Frontier is that its score improved from 2015.

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