Republic Flight 1557, operated as Frontier Airlines lost pressure and dropped from 24,200 to 28,600 feet over Aspen, and returned to Denver where it made an emergency landing.
The cabin did not depressurize and the oxygen masks did not descend, but the crew descended to deal with the cabin pressure issue.
The ERJ-190 made a safe landing with all of the 98 passengers and 4 crew uninjured.
Passengers were provided alternative flights from Denver to San Diego.


Arik Air flight W3-433 had to divert and make an emergency landing in Benin City, Nigeria, on May 12th.
A Scandinavian Airlines flight had to return and make an emergency landing at Munich International Airport, Germany, on March 24th.