Les Abend recently retired after 34 years as a Boeing 777 captain for American Airlines. He is a CNN aviation analyst and senior contributor to Flying magazine. The opinions expressed in this commentary are his. View more opinion articles on CNN.

(CNN)Before everyone goes all “Die Hard 2” and envisions airplanes being directed toward disaster by terrorist master minds, let’s please pause to understand reality.

I am referring to the July 17 event at Miami International Airport where it is alleged that an American Airlines 737 was sabotaged by an apparently disgruntled mechanic. The pilots determined there was a problem, discontinued the takeoff and safely returned the airplane to the gate, where it was then taken out of service for repair. It appears that the mechanic tampered with an ADM (Air Data Module), which transmits important information, like airspeed, pressure, temperature and more to the cockpit instrument panel. Airliners are designed with redundant systems to act as back-up for failures, so this airplane had more than one ADM. More than likely, the crew either noticed a difference between their airspeed indications immediately or they received a display warning about the failure on their center cockpit display, or both. Kudos to the pilots. Pilot: Why stowing away on an airplane undercarriage is a fatal mistakePilot: Why stowing away on an airplane undercarriage is a fatal mistakePilot: Why stowing away on an airplane undercarriage is a fatal mistakeEven if the airplane had become airborne, the pilots would have been able to safely return to the airport because they receive training for just such circumstances. In fact, as part of standard procedure, after accelerating to a speed of 80 knots (92 mph) pilots crosscheck their instrumentation for discrepancies during the takeoff roll.Read MoreSo how did this happen? Airplane mechanics are licensed by the Federal Aviation Administration. To maintain their certification, they must undergo a rigorous training– and recurrent training, as well. Airlines train mechanics for specific airplanes and for specific maintenance specialties. Whenever a mechanic repairs, replaces, or troubleshoots a problem, their signature and license number is recorded in a logbook. That signature is testimony to the airplane’s airworthiness. It’s a big deal.For all my four-plus decades of flying airplanes, professionally and recreationally, I never doubted a mechanic’s integrity. No mechanic would knowingly release an airplane for flight if they didn’t believe that they could put their own family on board, or so I thought—and still, mostly, believe.Court documents say the mechanic in question here (who was identified using surveillance video ) told investigators that he was upset over a contract dispute between union workers and the airlines, and the dispute had cost him money, according to CNN reporting. He said he tampered with the aircraft so he could get overtime working on the plane. Pilots shouldn't have to battle their planes for controlPilots shouldn't have to battle their planes for controlPilots shouldn't have to battle their planes for controlThis is of course ludicrous. Why a mechanic would deliberately sabotage an airplane and jeopardize not only the people on board, but his own livelihood is beyond my comprehension. Perhaps he believed that the warning systems would indicate a problem before the airplane left the gate. Listen: Do mechanics, like other union employees, get frustrated at airline management because of stalled progress at the negotiation table? Of course. But normally the reaction is to nitpick, or to find mechanical discrepancies that don’t affect the airworthiness of the plane, but enable the mechanic to keep the plane on the ground for a time. Repairing an item just prior to departure time creates delays, a circumstance that gets the attention of airline management.But the flying public should be aware that mechanics are screened and scrutinized the same as any airline employee. Most folks that reach the airline level of employment have a resume and a proven track record of repairing airplanes. Security issues are rarely a problem. Mechanics are a tight-knit group, working the same shifts together. Unusual behavior doesn’t go unnoticed.Follow CNN Opinion

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This unfortunate situation is an anomaly. There is no epidemic of terrorist mechanics infiltrating the airlines. For this circumstance, the safeguards worked. The pilots followed their procedures. Airplane warning systems were activated as designed. The culprit was discovered. Bruce Willis did not have to intervene. You can now board your flight.

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