CLEARWATER — An Allegiant Air McDonnell Douglas MD-83 took off from St. Pete-Clearwater International Airport on Jan. 19 bound for Ohio — and never made it.Instead, the crew reported "smoke in the cockpit" and headed back to the airport.That was one of more than three dozen mechanical issues reported by Allegiant pilots across the country from September to March. Nine of the incidents involved St. Pete-Clearwater International.Do the mechanical issues indicate that Allegiant — one of the nation's top low-cost airlines — is having problems safely maintaining its planes?"My colleagues have spent a lot of time reviewing incident data," said Indiana University transportation professor Clinton Oster Jr. "We have never been able to establish that an increase of these incidents is an indicator of a greater probability of accidents."The report detailing Allegiant's mechanical mishaps was based on pilot reports and compiled by the International Brotherhood of Teamsters' Aviation Mechanics Coalition, or TAMC. The Teamsters represent the pilots union, which is at odds with Allegiant. The airline and pilots are waiting for a federal judge to decide whether the pilots can strike.In a statement to the Tampa Bay Times, Allegiant defended its record. "The safety of our passengers and crew is … our number one priority. Allegiant has one of the best safety records among passenger airlines in the world and complies with all FAA regulations."Chris Moore, the TAMC chairman and veteran aviation mechanic who prepared the report, said Allegiant's pilots think the airline could do more to address mechanical issues."We gave our recommendations as to what we think would help them to run a better maintenance program," Moore said. "The pilots think (Allegiant) has a really disproportionate number of air returns and ground returns that they felt were not being addressed."Three of the nine incidents involving PIE — St. Pete-Clearwater also goes by its three-letter designation — saw Allegiant planes return to the airport. In addition to the smoke on Jan. 19, others were due to electrical and pressurization issues.One flight taxied back to the gate because of an aileron control issue. Two flights "aborted takeoff" and returned to the gate because of problems with the aft stair door indicator and "uncommanded" movement of the flaps.Two Allegiant flights that left PIE were diverted to Orlando Sanford International Airport, one with an "inoperative center fuel tank boost pump" and the other with a "left windshield anti-icing device" failure. That same windshield problem caused an Allegiant plane that left Orlando Sanford International to divert to PIE.The pilots said they're concerned, given the age of the airline's fleet: 70 percent of Allegiant's aircraft have an average age of 22.2 years, according to the report. About 77 percent of the fleet — 53 out of 69 jets — were built in the 1980s.The older planes are serviced by inexperienced mechanics, the union report said, noting that 55 percent of Allegiant's 1,800 mechanics have less than four years of experience and 35 percent have less than two years.But Oster said that although airframes age, airplane systems are regularly updated. "Just because the airplane is old," he said, "doesn't necessarily mean the components are old."