The EASA guideline CS-ADR-DSN contains inter alia requirements for the design of RWY strips. One of the main safety objectives of the RWY strip is to minimize damage to aircraft (especially nose landing gear) leaving the RWY laterally in the event of an incident (so-called veer off). In this respect, the following requirements are to be implemented in the RWY’s graded portion:
If there are deviations from the guidelines with regard to these characteristics, EASA allows the demonstration of an equivalent level of safety (ELOS) and thus, if necessary, safe and regular flight operations on the basis of a detailed safety assessment.
The safety assessments carried out by GfL in this context essentially comprise the following process steps based on the Safety Assessment Methodology (SAM) of EUROCONTROL:
Analysis of status quo:
Risk is generally defined as the link between the occurrence probability and the damage severity. In the present safety assessment, the quantitative determination of these two parameters in relation to the developed hazard scenarios is carried out as follows:
Determination of occurrence probabilities:
Determination of damage severity:
Within the framework of the final risk assessment, the determined probabilities of occurrence and damage severities are classified in the risk matrix according to ICAO Doc 9981 PANS-ADR or ICAO Doc 9859 SMM incorporating the following states:
The derivation of risk mitigation measures for intolerable and tolerable risks is based on the general reduction of veer off incidents on the one hand and concerning bearing strength and underground obstacle’s slope on the other. Possible measures include:
The development and definition of suitable risk mitigation measures is carried out in coordination with the aerodrome operator/client, taking into account the local conditions.
In the final result, the safety assessments carried out according to the above-mentioned methodology provide a comprehensive assessment in case of deviating bearing strengths and underground obstacles in the graded portion of the RWY strip at airports. Furthermore, they are the basis for applying for an ELOS procedure at the competent authority. The procedure can be transferred analogously to Runway End Safety Areas (RESA) and also allows the exclusive analysis and evaluation of bearing strengths without the additional investigation focus of underground obstacles.