Southwest Airline mechanics, including 80 based in Las Vegas.  The memo from Lonnie Warren, Southwest's senior director of tech ops production, called the airline's situation a "state of operational emergency."
Chicago Business Journal reporter Lewis Lazare obtained a copy of the memo on Friday and first reported about it
The memo was sent to 277 mechanics at Houston, 167 mechanics at Orlando, 375 mechanics at Phoenix and another 80 at Las Vegas.
Some 2,400 mechanics work full time for Southwest. All mechanics belong to the Aircraft Mechanics Fraternal Association (AMFA).
Warren wrote in the memo: "We've been experiencing an unusually high number of out-of-service aircraft over the last few days. Due to this issue of service aircraft, our operation requires all of our scheduled aircraft maintenance technicians and inspectors.
Southwest's maintenance organization issued a call to maximize the number of mechanics available for work. On an average day, the airline plans for as many as 20 aircraft to be unexpectedly out of service for maintenance items. Each aircraft has 750 aircraft, more than doubled the daily average. So that we can promptly return aircraft to service.
– Southwest statement from Michelle Agnew
The airline is the most prolific carrier at McCarran International Airport, flying more than 15 million passengers in and out of the Las Vegas each year. 3.
"On any given day, maintenance items and weather can result in daily cancellations for the airline operation, "Agnew said in an email Saturday. "The uptick in maintenance items we have done over a few days a year, but we do not have a breakdown in a single day."
The Chicago Business Journal has described the talks as contentious.
The mechanics have been trying to negotiate a new contract with the airline since August 2012 .
"We remain steadfast in our commitment to secure a new contract for our hard-working mechanics," Agnew wrote.