Draft:Airport Risk Plan

Translated from "Piano di rischio aeroportuale". The airport risk plan (in italian "Piano di Rischio Aeroportuale", acronym PRA) is an urban planning tool of Italian legislation, aimed at protecting areas near airports affected by the trajectories of aircraft during take-off and landing. The take-off and landing phases are statistically at greater risk of air accidents and the resulting damage can affect built-up areas near the airport, especially in cases of proximity to residential areas.

Flight phases

In the municipalities where the airports and the related landing and take-off directions are located, the Italian state legislation regarding the air navigation sector prescribes the adoption of suitable plans aimed at limiting the damage caused by possible air accidents, through the control of elements present in the territory potentially capable of amplifying the risk. In particular, the aeronautical discipline referred to in the second part of the Italian Navigation Code (R.D. n.30/1942 and subsequent amendments - hereinafter the Code)^[1] provides, in book I title III chapter III, limitations on private properties located in the areas adjacent to airports open to civil traffic. In compliance with this regulation, the territorially competent municipalities must adopt specific Airport Risk Plans, whose urban scope of application depends on the directions of take-off and landing, the characteristics of the runway and the type of aircraft that can operate in the airport.

The contents and characteristics of the Airport Risk Plan are indicated in the Regulations for the construction and operation of airports^[2] and in Circular APT-33 of 30/08/2010^[3], issued by the National Civil Aviation Authority (ENAC). The Plan is essentially composed of various analysis documents, tables for the identification of protection zones, as well as implementation rules. Chapter 9^[4],paragraph 6 of the Regulations indicates the guidelines to be followed for the drafting and approval of the airport risk plan defined as "a document containing the indications and prescriptions to be incorporated into the urban planning tools of individual municipalities" […] "aimed at protecting the territory from the consequences of a possible accident". Circular APT-33/2010^[3], on the other hand, defines in a more precise manner the criteria and indications useful to municipalities for the drafting of the PRA, specifying its minimum contents. Compliance with the indications contained in the Circular "is essential for obtaining the opinion of ENAC" necessary for the adoption of the PRA.

Types of airport risks

Airport risk management is part of flight safety activities, defined by ENAC as "a coherent set of activities and actions aimed at developing flight safety, in terms of protecting the safety of people and property involved in aeronautical operations in a broad sense," which "constitutes one of the essential connotations of the governance activity of the national civil aviation system".^[5]

The current aeronautical regulations[^[6]refer to different types of risk linked to flight activity near airports:

• risk generated by the territory with respect to flight activity, which concerns the presence of possible obstacles or dangers for the safety of air navigation^[7], such as structures that obstruct flight paths, emissions of electromagnetic waves, emission of smoke, reflective surfaces, etc.; in the second part, first book, title III, chapter III - constraints of private property - of the Code it is foreseen that for this first type of risk ENAC is to establish the limitations to obstacles for air navigation and potential dangers (Code, art. 707, paragraphs from the first to the fourth^[8]);
• risk generated by flight with respect to the territory, in particular for the possibility of accidents in the areas surrounding the airports in the directions of take-off and landing^[9]; for this second type of risk, however, it is up to the territorially competent municipalities to adopt specific airport risk plans whose purpose is to limit human presence and to identify incompatible activities due to the potential amplification of the consequences of accidents (Code, art. 707, fifth paragraph^[8]);
• risk within the airport, the Regulations provide in addition to the Airport Risk Plan also the Airport Emergency Plan^[10]which allows to deal in an organised way with potentially dangerous events within the airport grounds or in adjacent areas, identifying the procedures to coordinate the response action of different bodies or services. This plan is adopted by ENAC which also determines its area of ​​application in coordination with the other interested parties.

Nature of the bond

From the wording of the reference legislation (in particular from the aforementioned Regulation in chapter 9 par. 6.3^[4]), the nature of the PRA is evident as a constraint superior to the municipal urban planning instrumentation. In fact, article 707 of the Navigation Code[8], in order to assess the dangerousness, does not attribute any discretion to the municipal administration, the latter being established by the regulatory discipline attributed to the aeronautical authority. Therefore, according to the jurisprudential references, the provisions produced by the adoption of the PRA are immediately effective.

Pursuant to the aforementioned Regulation (chapter 9 par. 6.2^[4]) the limitations deriving from the implementation of the plan refer to new works and new activities to be established in the territory surrounding the airport. Therefore, the PRA, even in the presence of activities or buildings that are also clearly incompatible, does not produce ablative or interdictory effects on the existing activities. Therefore, no prohibitions or limits should be introduced concerning these realities, except for any prohibitions on future changes that would increase the risk.

The limitations imposed by the PRA, which do not in fact exclude the possibility of building on the areas concerned but only limit their intended uses within those already permitted by the municipal urban planning instruments, are not included among the constraints preordained for expropriation, subject to specific regulations^[11] and to the simultaneous provision of compensation.

Plan formation procedure

The main regulatory reference for the airport risk plan formation procedure is found in the aforementioned art. 707^[12] of the Navigation Code.

In particular, the law establishes the binding content of the PRA and establishes that for the areas concerned, the territorially competent municipalities adopt the appropriate airport risk plans, also on the basis of any regional directives, in compliance with the ENAC Regulation on the construction and management of airports.^[2].

The procedure to be applied to the adoption of the PRA is partly indicated in the specific directives issued by ENAC (Airport Regulations in particular in chapter 9)^[4] par. 6.7, Circular APT-33/2010 in particular par. 6^[3]), however, these do not identify the administrative body responsible for adopting the plan nor do they provide indications on the procedure's progress. Also in consideration of the general regulatory content of the plan within the scope of urban planning regulations, the majority of the Italian municipalities involved have approved the PRA at the City Council^{[13][14][15][16][17][18]}.

PRA protection zones

PRA protection zones (as per ENAC airport regulations - runways type 3-4)^[2])

The purpose of the PRA is to mitigate the risk generated by flights with respect to the territory based on the statistical probability of accidents. To this end, the plan identifies areas with different degrees of risk and defines for them the restrictions to the current urban planning regulations regarding human presence, as well as incompatible activities due to the potential amplification of the consequences of any accidents.

Depending on the degree of risk, according to the methods indicated in chap. 9 par. 6.5 of the Regulations^[4], four protection zones are identified, where, gradually depending on the degree of risk, the PRA rules provide limitations on possible residential constructions in order to mitigate the exposure of inhabitants to the risks of air accidents. The limitations also concern incompatible activities (due to the possibility of amplification of damage), sensitive activities (such as schools) and activities involving crowding (due to the presence of a significant number of people).

The protection zones, as defined in chap. 9 par. 6.6 of the Airport Regulations^[4], are:

• zone A, where the human load is limited to the maximum;
• zone B, where the possibility of a modest residential function is foreseen;
• zone C, where the possibility of a reasonable increase in residence is foreseen;
• zone D, where it is planned to guarantee a development compatible with the operation of the airport.

Incompatible, vulnerable and crowding activities

Pursuant to the Airport Regulations chap. 9 par. 6.6^[4], the mitigation of the risk arising from an air accident is based on the identification of activities whose presence in the area near the airport determines critical issues relating to two types of reasons:

• presence of people who could be victims of the accident (residence, crowded places, vulnerable activities);
• activities which, if involved in a possible accident, may generate the risk of damage being amplified (fuel distributors, flammable liquid depots, chemical industries, etc.)

The PRA rules, in fact, provide limitations on residential construction in order to reduce the exposure of residents to the risks of air accidents.

With regard to all other non-residential activities, it is necessary to define objective methods of risk assessment based on the two aforementioned orders of reasons. The reference standard does not provide precise indications to this end, nor has a univocal method of defining risky activities been found in the airport risk plans drawn up by the various Italian municipalities.

A possible method may refer to the broad correspondence between the activities that are to be considered at risk in the airport area and the activities already subject to the current legislation relating to visits and fire prevention checks. These activities, with the appropriate adjustments, can be deduced from the list reported in Annex I of the Presidential Decree 151/2011^[19] and subsequent amendments, where they are classified into three risk categories based on specific factors.

In summary, activities involving critical issues can be traced back to the following classification:

• residential activity
• incompatible activities (due to the possibility of damage amplification, such as fuel depots);
• vulnerable activities activities (such as schools and hospitals);
• activities involving crowding (due to the presence of a significant number of people, such as shopping centres).

Risk impact - isorisk lines

The Navigation Code^[1], in addition to the provisions relating to the Airport Risk Plan, provides for further protection regulations that the municipalities involved must take into account in the exercise of their functions of planning and management of the territory. In fact, art. 715^[20] of the Code provides that ENAC identifies the airports for which to carry out the "risk impact assessment"..

Iso-risk lines diagram (as per ENAC Policy^[21])

With reference to this assessment, ENAC has provided the clarifications referred to in chap. 9 par. 6.8 of the Regulations^[4] and in the document "Implementation policy of art. 715 of the Navigation Code"^[21] in which, among other things, it is reported that the airports involved are those with a traffic volume greater than 50,000 movements/year and close to sensitive and highly urbanized areas.

With reference to the aforementioned Policy document, in particular to section 1 "evaluation methodology", based on the risk to people on the ground, deriving from a possible air accident, the so-called "isorisk lines" are drawn which delimit the following areas:

• high protection;
• internal;
• intermediate;
• external (outside the isorisk lines).

The difference between the PRA protection zones and the areas of the isorisk lines is that in the former case we calculate the statistical risk deriving from the international data for the airport category is considered, while in the latter case we calculate the risk based on the specific flights and aircraft operating in the concerned airport.

The areas identified by the isorisk lines overlap in part with those of the protection zones A, B, C and D of the PRA, therefore the municipalities involved must operate a coordination between the two disciplines to report the relative provisions within their own urban planning tools.

Notes

1. "Codice della Navigazione". Enac.
2. "Regolamento per la costruzione e l'esercizio degli aeroporti". ENAC (in Italian).
3. "Circolare ENAC APT 33". ENAC (in Italian).
4. "Regolamento ENAC cap. 9" (PDF).
5. "flyght safety". Enac.
6. "Normativa aeronautica". 17 May 2025.
7. "Ostacoli e pericoli per la navigazione aerea". ENAC (in Italian).
8. "Codice della Navigazione art. 707". www.gazzettaufficiale.it.
9. "Aerohabitat: Aeroporti e piano di rischio". www.aerohabitat.eu.
10. "Piano di emergenza aeroportuale - Ordinanza ENAC 13/2016" (PDF).
11. "DPR 327/2001 - Testo unico esproprizioni". www.gazzettaufficiale.it.
12. "Codice della Navigazione art. 707". www.gazzettaufficiale.it.
13. "PRA Consiglio Comunale di Bari".
14. "PRA Consiglio Comunale di Bologna".
15. "PRA Consiglio Comunale di Venezia". 12 December 2019.
16. "PRA Consiglio Comunale di Napoli".
17. "PRA Consiglio Comunale di Treviso".
18. "PRA Consiglio Comunale di Reggio Emilia".
19. "DPR 151/2011". www.vigilfuoco.it.
20. "Codice della navigazione art. 715".
21. "Policy di attuazione dell'art. 715 del Codice della Navigazione". ENAC (in Italian).

External links

• Rome: Risk Plan for Fiumicino Airport
• Milan: Airport constraints for Linate and Bresso airports;
• Naples: PRA Risk Plan for Capodichino Airport.

[[Category:Urban planning]] [[Category:Aviation]]