GASP Key Concepts and Metrics


The GASP presents some of the key metrics used in its goals, targets and indicators. Some of these concepts are new or represent an evolution from previous metrics used by ICAO to measure safety performance.

 Accident Rate

ICAO's primary indicator of safety in the global air transport system is the accident rate based on scheduled commercial operations involving fixed-wing aircraft with a maximum certificated take off mass greater than 5 700 kg. Aircraft accidents are categorized using the definition provided in Annex 13 — Aircraft Accident and Incident Investigation.


Departures data is collated by the ICAO Air Transport Bureau using a combination of inputs. Estimates are made where data has not been provided by States, otherwise State data and commercial sources are used to obtain the best estimate of the actual number of departures. As new data is provided to ICAO, it is incorporated into the database, which may result in small changes to the calculated rates from year to year. The fatal accident rate is based on accidents that involve one or more fatal injuries using the definition provided in Annex 13.


Statistics and data on accidents and incidents can be found using the ADREP et al. application available via the ICAO integrated Safety Trend Analysis and Reporting System.

 Priority Protocol Questions for a Safety Oversight System

​There are currently about 1000 protocol questions (PQs). Although all the Universal Safety Oversight Audit Programme (USOAP) PQs contribute equally to the effective implementation (EI) score, they do not all equally impact the operational safety risk. For example, those PQs relating to documentation, although important, have a less direct impact to operational safety risk. Some PQs, if found to be unsatisfactory, could have a significant impact on operational safety and could indicate an elevated risk of a significant safety concern (SSC). Many States are finding it a challenge to address a significant proportion of the PQs. Given that these States face difficulty addressing all the PQs, it is worthwhile to give them an indication of which PQs may require closer attention or priority.


The term "priority PQs" refers to PQs that have a higher correlation to operational safety risks. The identification of priority PQs is important so that States can focus their resources accordingly. It should be noted that the whole set of PQs continue to be essential to comprehensively assess the effective implementation of a safety oversight system by a State.


Important note: ICAO is currently in the process of selecting the priority PQs. They will be available shortly.

 State Safety Programme (SSP) Foundational PQs

The term "foundation of an SSP" refers to a subset of the Universal Safety Oversight Audit Programme (USOAP) protocol questions (PQs) that have been identified as fundamentals and are considered as prerequisites for sustainable implementation of the full SSP. These are referred to as "SSP foundational PQs". SSP foundational PQs are grouped into subject areas derived from Annex 19, Safety Management and Doc 9859, Safety Management Manual. States can prioritize and address these PQs when conducting the SSP gap analysis or while defining the SSP implementation plan. The concept of "foundation of an SSP" is intended to replace the 60 per cent effective implementation (EI) score previously used in the GASP as a threshold to progress into implementation of the SSP. The intent is that these PQs be included in the SSP implementation planning to ensure sustainability.


The full list of SSP foundational PQs can be found using the SSP Foundation tool available via the ICAO iSTARS.

 Safety Oversight Index

The safety oversight index of a State is an indicator of its safety oversight capabilities. Every audited State has a safety oversight index. It is a number greater than zero where the number one represents a level at which the safety oversight capabilities of a State would indicate the minimum expected capabilities considering the number of departures, as a proxy to the size of that State's aviation system.


The safety oversight index is a mathematical function comparing a State's effective implementation (EI) score and traffic volume to a safety oversight target EI score which is computed using a global log-linear regression. The safety oversight index will tend to decrease over time if traffic increases and the EI score remains unchanged.


The safety oversight index is broken down into three functional categories:


  • Operations – this category groups EI scores for the Universal Safety Oversight Audit Programme (USOAP) audit areas related to personnel licensing and training (PEL), aircraft operations (OPS) and airworthiness of aircraft (AIR)
  • Air navigation – this category groups EI scores for USOAP audit areas related to aerodromes and ground aids (AGA) and air navigation services (ANS)
  • Support functions – this category groups EI scores for USOAP audit areas related to primary aviation legislation and civil aviation regulations (LEG), civil aviation organization (ORG) and aircraft accident and incident investigation (AIG)


The safety oversight index is a new concept introduced into the 2020-2022 edition of the GASP and serves as one of several indicators of a State's safety oversight capabilities. States should focus on achieving all of the GASP goals and targets and continually improve their EI score as part of their responsibilities for the management of safety.


The Safety Oversight Indexapplication is available via the ICAO iSTARS .

Share this page: