The Reality of Inverted Flight: Why Commercial Aircraft Don't Maneuver This Way

Popular culture frequently portrays aircraft performing inverted flight, a thrilling scene in movies and TV shows. However, it is important to understand that such maneuvers are not within the operational parameters of commercial airliners, such as the DC-9 and its derivatives, including the MD-80 series. These aircraft are specifically designed for safety, efficiency, and passenger comfort, not for inverted flight.

The Design and Operation of Commercial Aircraft

Commercial airliners like the DC-9 and MD-80 are primarily designed for safe and efficient operations in the commercial air transport industry. They are engineered to adhere to strict safety protocols and operational guidelines set by regulatory bodies. Inverted flight, which involves flying the aircraft upside down, is a maneuver typically reserved for aerobatic aircraft, which are specifically designed to handle such maneuvers.

While these aircraft can perform various flight maneuvers, flying inverted is not within their primary operational scope. Attempting such a maneuver would not only be outside of the aircraft's design specifications but also highly dangerous. This is why commercial airliners do not include the capability for inverted flight in their systems and training protocols.

Practical Implications and Safety Concerns

The portrayal of inverted flight in movies and television adds excitement and drama, but it does not accurately reflect the capabilities or safety protocols of commercial airliners like the DC-9 or MD-80. Commercial aircraft are equipped with sophisticated safety systems, including fail-safes that would prevent such dangerous maneuvers from occurring. If an aircraft were to encounter a malfunction that could lead to inverted flight, the safety systems would automatically correct the situation to maintain structural integrity and control.

Moreover, aircraft are designed to prioritize altitude gain when encountering any issue that could compromise the flight. If a jack screw (a crucial component in aircraft control systems) were to fail, the aircraft's priority would be to regain altitude and ensure safe and controlled descent, rather than trying to maintain a flat or inverted position.

The Jack Screw Failure: A Case Study

The jack screw is a critical component in the flight control system of aircraft, such as the Boeing 737. In the case of Alaska Airlines flight 261, a tragic event occurred due to a catastrophic failure of the jack screw. This failure was not due to malice or negligence but rather a result of a systemic issue that arose from improper maintenance procedures.

According to Drift Into Failure by Sidney Dekker, a professor of human safety engineering and a certified 737 pilot, a common issue faced by maintenance crews when accessing the jack screw involved cuts and injuries due to the small access panels used to reach the component. As a result, the airlines requested the manufacturer to extend the service interval, which was granted. However, due to the type-certification of the jack screw, which allows for its use in various types of aircraft, another operator inquired about extending the service interval to include other maintenance tasks. The manufacturer agreed after performing a thorough failure analysis.

Unfortunately, these extended service intervals led to the jack screw on Alaska Airlines flight 261 going more than 3000 hours without lubrication, eventually resulting in catastrophic failure. The failure was a complex system issue with no single point of blame.

It is important to understand that while movies and TV shows often dramatize such events, in reality, commercial aircraft are designed to operate safely under a wide range of conditions, and the actions of maintenance crews and pilots are meticulously controlled to ensure such failures do not occur.