How safe are commercial aircraft

Flight safety

Control, control and control again

It is a particular challenge to coordinate the growing number of take-offs and landings at major airports in such a way that all aircraft get safely into the air and back to the ground.

An airplane is a complex means of transport full of electronics. As a passenger, you have to be able to rely on the fact that all components that are necessary for a safe flight actually function perfectly. This is exactly what strict rules for the maintenance of commercial aircraft are supposed to guarantee.

In Germany, Regulation No. 2042/2003 of the European Union (EU) "on the maintenance of the airworthiness of aircraft (...)" of November 20, 2003, includes and stipulates events for each important component that are dependent on time or flight hours which security checks are to be carried out and when.

Every airline is obliged to have a maintenance program approved by its responsible aviation authority - in Germany this is the Federal Aviation Office.

This program relates to the flight pattern of the respective aircraft, which is why the intervals of the safety checks differ. If these intervals are not adhered to, the Luftfahrt-Bundesamt can initiate proceedings due to an administrative offense.

Mandatory: various security checks

It starts with the "trip check" - so that the captain or co-pilot check whether all instruments are working before each take-off. If necessary, technicians change tires or replace the brakes. They also examine the aircraft for cracks and check the oil and hydraulic fluid levels.

Depending on the type of aircraft and use, an "A-Check" is due every two months, which takes a few hours: All technical systems that are important for flight operations are checked and the cabin is maintained.

In addition, a "B-Check" is required for some types of aircraft every three to five months. This takes more time because the technicians dig deeper into the electronic and structural inner workings of the aircraft.

Commercial aircraft are subjected to a "C-Check", and thus a thorough check of all systems, approximately every 15 to 18 months. In the process, the fairing is also partially exposed so that the aircraft body can also be examined in detail. The "C-Check" takes one to two weeks.

A major overhaul of the aircraft takes place every six to ten years: First, the exterior paint is removed, and then the machine is completely dismantled, all parts thoroughly examined and damaged parts replaced if necessary. Among other things, X-rays are used for this. Duration: four to six weeks; Cost: several million euros.

In the cockpit: everything is available twice

Once a machine is in the air, numerous automatic control and warning instruments support the pilots in their work. Overall, the motto "Two is better" applies to the cockpit - that is why all the important control and navigation systems in aircraft are available at least twice and function independently of one another. If one of them fails, it can be replaced immediately.

The same applies to the human component of flying. Because every airliner is manned by at least two pilots who take turns; the copilot controls the aircraft as safely as the captain.

Compared to the electronic aids in the air, the pilots' equipment when navigating on the runway is poor. On the ground, pilots have to rely on the instructions from the tower and their eyes. Because so far very few commercial aircraft have a signal-based navigation aid for airports.

The Airbus A380 is the first type of aircraft to be fitted with such a system. It was developed at the "Institute for Flight Systems and Control Engineering" at the Technical University of Darmstadt.

It is based on an "Airport Moving Map": a display on which the pilot can see his position at the airport at any time, as has long been possible in navigation systems in cars. In this way, the pilot can find his way better at little-known airfields and when visibility is poor.

Preventing accidents at the airport

However, the technology from Darmstadt can do even more: It can prevent "runway incursions", i.e. incidents in which an aircraft, vehicle or person is unauthorized in an area that is intended for take-offs and landings.

To do this, all aircraft would have to be equipped with the "Airport Moving Map", which would send and receive the signals required for the software and also receive data from the tower. In this way, every pilot would be warned immediately if, for example, he was coming dangerously close to a runway in use.

And it is precisely this signal-based navigation technology that is of enormous importance in terms of safety against the background of growing air traffic and more and more take-offs and landings.

Nevertheless, even newly delivered aircraft are not necessarily equipped with the system from Darmstadt, which has undergone such extensive and protracted certification in aviation.

"If a PC crashes at home only once a year, you're happy. But we have to guarantee that the system will not crash a single time during the entire service life of a machine, i.e. 20 or 25 years," explains engineer Christian Drege who works on the project of the Institute for Flight Systems and Control Engineering.

Passenger safety: could be improved

But there are not only improvements for the cockpit that would make flying even safer, but also for the passenger compartment: A US research company has found that in a crash, aircraft often break apart directly in front of and behind the wings, causing the worst damage there arise. At these points there are rows of seats for passengers in the machines.

Removing the seats and placing toilets or aisles there could probably save many people's lives in the event of a crash. But such a measure is economically unattractive for the airlines - fewer seats mean less income.

The safety belts in the aircraft are also not up to date: the passengers still fasten their seat belts with a lap belt, although a three-point system such as in a car or helicopter is technically feasible and technically feasible.

As long as the main aim is to fly cheaply and measures to improve safety in the passenger compartment are not explicitly demanded, little will change there.