When does a commercial plane get retired from use?

Airline companies decide when to retire a plane based on the structure of the airplane, engine’s strength, average duration of its flight etc. However, there are several major factors that are taken into consideration before an airplane is retired from use.

The first one is the number of years the plane has been in service. Some planes such as the Boeing-747 and the Airbus-300 are considered as “old” after 20 years of service. While the age-factor of the plane is looked into, the number of take offs and landings a plane has done is also kept in view.

Airplanes face metal fatigue during take offs and landings. This causes the metal to lose some of its strength. As such it becomes weaker with each flight. This “metal fatigue” is the second major factor that is considered while retiring an airplane.

The third important factor is the number of hours a plane has done. Most airplanes fly at an altitude of around 30,000 feet and temperatures at this height average -45 degree C while on the ground the average temperatures may be around 40 degree C.  This causes the metal to contract and expand on each flight. The metal body of the aircraft faces temperature changes within 15 minutes. This causes additional fatigue and causes the airplane to lose strength.

The fourth factor is the financial side. As a plane gets older, spare parts become more expensive and the aircraft may spend more time on the ground getting checked out. Also, older aircraft guzzle more fuel than modern counterparts. As a result, the decision to retire an aircraft is one that involves cost-benefit analysis: whether it is cheaper to maintain the plane and keep flying or to replace it with a newer aircraft.

Also comes into play the commercialization of the aircraft. Older aircrafts will not offer the amenities/technologies (both in the cabin and in the cock-pit), fuel efficiency and comfort that newer aircrafts will offer.  

As such it is a mixture of technology/comfort, maintenance/ fuel costs of running that aircraft and the number of cycles and pressurization the aircraft has gone through that are taken into consideration when retiring a plane.

Seriously, it‘s a bit complicated –even the definition of what “retired” means is complicated when commercial airplanes get retired.