Nothing in an airport is superfluous. Everything is controlled and that is how it should be because, although it impossible to guarantee absolute safety, risks can be eliminated or mitigated to an acceptable level without causing injury to people or damage to property. Aeronautical safety studies are designed precisely to consider each and every one of these cases in order to identify, prevent and minimize any risk of accident or incident at airports, either on the land side or on the airside. Thanks to this work done by the entire aeronautical community, today’s world air transport has very high levels of safety, and is constantly reviewed through an ongoing process of hazard identification and risk management.

The rapid development of new technologies introduces factors that did not previously need to be taken into consideration. The advance in business models is focused on the construction of increasingly large aircraft that must operate at airports with all safety guarantees. These constraints generate added difficulty to maintain the quality standards that have been achieved. This is a constant effort, and in many cases it is necessary to propose alternatives, for example, aeronautical safety studies that guarantee an equivalent level of safety.

In general, these studies will be used in cases where the correction of a deviation is not feasible or is technically, operationally, environmentally or economically excessive, and the safety degradation can be overcome by means of procedures that offer reasonable, practical solutions.

The airport operator, airlines and air navigation providers have their own safety management systems, but it is of little use if each group pursues its own objectives in a way that is not coordinated with the other agents involved in the operation. The different safety management systems have to be integrated to form part of an interlocking system in which all pieces operate in a synchronized manner.

The levels of safety guaranteed by global air transport today represent an achievement based on the determination and efforts of the aviation community as a whole

International regulations

In the Convention on International Civil Aviation (1944), also known as the Chicago Convention, the main rules of aeronautical law were laid down in order to achieve adequate safety in air transport: at the end of World War II it was important to review the international agreements on civil aviation in a period of consolidation and development of the world aviation sector, and commercial aviation in particular.

The Convention was the seed of the International Civil Aviation Organization (ICAO), a specialized agency of the United Nations created that same year to promote the safe and orderly development of international civil aviation around the world. The ICAO established, and continues to establish, the necessary standards and regulations for aviation safety, efficiency and environmental protection worldwide. Strengthening the safety of the global air transport system is its primary objective. The ICAO Global Aviation Safety Plan (1998) was developed to reduce the number of accidents regardless of the number of flights.

As the increase in air traffic leads to an increase in the risk of accidents, a progressive improvement in safety management has become necessary in order to maintain adequate safety levels. Its objective is to progressively reduce the number of accidents regardless of the growth of air traffic, taking into account that:

  • No human activity or human-designed system can be totally free of risks and errors.
  • The elimination of all accidents (and serious incidents) is impossible.
  • Failures will continue to occur, despite the most successful prevention efforts.
  • Risks and errors are acceptable in an implicitly secure system, provided they are under control.

The levels of safety that global air transport guarantees today represent an achievement based on the determination and efforts of the aviation community as a whole. Safety must be a dynamic process that is adapted constantly, while maintaining the objectives achieved with the goal of achieving the lowest possible risk, without forgetting the progressive adaptation to the changes that will be taking place.

TRAINING SEMINARS. In 2012, Ineco gave a Safety Seminar with Aena Internacional in Mexico. In the centre of the photo, from left to the right, Sara García Ramos, mathematician and author of this article, and Rosario González, aeronautical technical engineer, both from Ineco.

In this regard, the ICAO document Procedures for Air Navigation Services –Aerodromes (PANS-Aerodromes) (Doc. 9981), first edition 2015–, details the operational procedures to be applied by aerodrome operators to ensure safety, especially when it is not possible to fully comply with the required technical specifications.

It is important to note that the cost (economic, operational, environmental, etc.) of any action must be balanced against the safety benefit, so as to generate the least possible socio-economic impact without compromising the equivalent level of safety.

According to Article 15 of the Convention on International Civil Aviation, all aerodromes open to public use under the jurisdiction of a Contracting State must provide uniform conditions for all aircraft of all other Contracting States. Likewise, Articles 28 and 37 of the same Convention provide that each State shall provide in its territory airports, other air navigation facilities and services in accordance with the Standards and Recommended Practices (SARPs) developed by ICAO. Airport operators must therefore have an airport certificate in order to be able to operate, and in the case of newly built airports or where new runways are to be put into service, this is a prerequisite before opening to traffic. The loss or modification of the certificate will result in the loss or immediate modification of the authorization to admit air transport. The certificate accredits the ability of both the infrastructure and the operator to carry out air transport operations.

In Spain, the Aviation Safety and Security Agency (AESA) is the aviation authority responsible for granting the certificate and monitoring any problems or deviations. Within the required documentation, are the aeronautical safety studies whose purpose varies from the justification of the fulfilment of the requirements to the evaluation of the deviations detected.

Ineco has been carrying out this type of study in Spain for over 10 years, working in air navigation, for all airports and heliports in the Aena network, as well as at other international airports in countries such as Mexico, Israel and Italy. Also, during this period Ineco has supported the certification processes at the airports and heliports of the Aena network – guaranteeing results and procedures.

Safety must be a dynamic process that is adapted constantly with the goal of achieving the lowest possible risk levels

Aeronautical safety studies

The objective of an Aeronautical Safety Study is to try to analyse an aeronautical problem, to determine possible solutions and select the most acceptable option, without adversely affecting safety. In short, the purpose of these studies is to:

  • Detect the causes of the problem and evaluate the possible impact on the safety level.
  • Present alternative means to ensure the aircraft operations safety.
  • Evaluate the effectiveness of each alternative.
  • Recommend procedures to act on the causes and/or diminish the effect or the occurrence of the consequences.

To achieve these objectives, the studies are based on a technical analysis. Technical analyses seek to justify deviations based on the possibility of achieving an equivalent level of security by other means. In addition, these analyses are generally applied in situations in which the cost of correcting issues that violate standards is excessive, but the negative effects on safety can be overcome by procedures that offer practical and reasonable solutions.

An aeronautical study may be conducted when aerodrome standards cannot be strictly met as a result of development or extension. This study is most frequently undertaken during the planning of a new airport or during the certification of an existing aerodrome.

Mathematical studies to determine the probability of an event

Risk analysis can be focused qualitatively or quantitatively involving mathematical models and input by groups of experts who contribute their knowledge to the process.

Quantitative models are a set of analytical techniques based on mathematical arguments used to assign probability of occurrence to a given fault or event in order to evaluate the level of risk associated with a given operation.

Runway excursion is the most frequent and catastrophic accident with respect runway operation. For this reason, a specific Mathematical model for the assessment of runway excursion probabilities has been developed for this type of incident.

Ineco has been carrying out this type of study in Spain for over 10 years, working for all airports and heliports in the Aena network, as well as in other international airports in countries such as Mexico, Israel and Italy

Severity and Probability Metrics

The accident database’s statistical model is based on the collection and processing of accident data in order to establish the quantitative relationships necessary to evaluate the safety of a system. The creation of a database with statistics on accidents, incidents and events and their analysis, makes it possible to determine the probability of occurrence for the most frequent events in an airport.

The tables show some examples as a guide, taking into account the international ICAO standard, severity classification matrix and probability classification matrix.

Severity classification matrix.

Probability classification matrix.


In addition to hazards and risks, there are also mitigating and aggravating factors, such as:

  • The procedures for coordinationbetween pilots, air traffic controllers and airport staff affect the operation; proper coordination of these procedures can minimize the risks.
  • Wildlife, especially birds, in an airport environment, can cause serious economic and safety issues.
  • Runway design: dimension, shoulders, strips, strength, signalling, lighting, etc., must be taken into account in any possible risk, especially before a runway excursion.
  • Airports should provide the appropriate level of fire protection and rescue, depending on their category.
  • Air navigation assistance is essential in airport operations. Having the right assistance based on the type of operation allowed at the airport minimizes potential risks.