Tuesday, July 17, 2018
Transport Canada - Aviation Safety Letter Exchange of Safety-related Information: A Tool to Enhance Safety

Exchange of Safety-related Information: A Tool to Enhance Safety

by Serge Thibeault, Regional Safety Manager, Eastern FIRs, NAV CANADA


The aviation industry is upgrading its safety management toolbox to include proactive/predictive processes such as hazard identification and risk analysis, normal operation safety survey (NOSS) and line operation safety audit (LOSA) to complement existing reactive processes such as accident or incident investigations. These various sources of data provide a wealth of information for analysis and identification of potential safety hazards and risks. While most organizations have developed the ability to collect and analyze data pertaining to their own organization, a more complete picture is required for tackling a number of the safety issues facing the industry. This complete picture can only be obtained through the inter-organizational exchange of safety-related information.

The chart below illustrates the national picture in 2007 of some of the events being tracked by NAV CANADA as reported through its Aviation Occurrence Reporting (AOR) system, which feeds Transport Canada’s Civil Aviation Daily Occurrence Reporting System (CADORS) database.

Type of Occurrence Chart

Although NAV CANADA tracks these issues, its ability to be proactive in mitigating them is quite limited, since an in-depth understanding of the "whys" behind these events requires input from other industry stakeholders. It is important to note that none of the events shown on the graph above resulted in catastrophic outcomes, thanks to the strength of the aviation industry’s defences. However, each time one of these events occurred, it pushed the safety envelope and occasionally required quick human intervention to re-establish safety.

To illustrate how sharing safety information has benefited the aviation industry, the sections below describe some of the advances made in understanding standard instrument departure (SID) deviations, course deviations, and altitude deviations.

SID deviations
A SID deviation is defined as any deviation from the altitude or direction required to follow a standard instrument departure. A rise in SID deviations by pilots departing from Montréal Trudeau International Airport was identified in the summer of 2007. In response to this trend, NAV CANADA held a forum for industry stakeholders to share information. As a result of this effort, all participants gained a greater understanding of some of the underlying factors, such as:

  • Flight management system (FMS) programming errors linked to last-minute runway changes
  • Confusion of a SID name (KANUR 2) with an en-route fix name (KANUR)
  • Pre-filed flight plans loaded in the FMS based on the company dispatch’s assumption regarding which SID will be flown, but the flight crew forgot to update the FMS when ATC actually assigned the SID.

Armed with a better understanding of the issues, the industry is now in a better position to develop appropriate and effective mitigation.

Course deviations
A course deviation is defined as any deviation from routing, including gross navigational errors, standard arrival or departure paths in terms of direction (excluding SIDs) and any erroneous tracks.

Course deviations are a complex issue as there are a number of different reasons for which they occur. Consider the following example: the dispatch department for a flight from Asia to North America had filed a flight plan which was forwarded from the airline’s dispatch office in North America to an air navigation service provider (ANSP) in Asia and simultaneously to the flight crew. A while later, a second flight plan, which included a different route, was entered into the system for the same flight through an Asian dispatch. As the flight progressed to North America, the flight plan information also travelled from ANSP to ANSP and finally, many hours into the flight, in the Montréal flight information region’s (FIR) airspace, the flight deviated from the course expected by NAV CANADA’s controllers. To fully understand where the break in communication occurred in this type of event required investigating whether it was somewhere between the various ANSPs involved, between the dispatch and their crew, or between crew members on board the flight. Without collaboration between the various stakeholders in tracking down the problem, it would be difficult for NAV CANADA or any other organization to implement appropriate and effective mitigation.

Altitude deviations
An altitude deviation is defined as any deviation by any aircraft from an assigned or designated altitude (SID deviations are excluded). This may include deviations due to turbulence or other weather events, deviations from an altitude passed from one area control centre (ACC)— specialty or sector—to another. Flights can be IFR or VFR.

The industry has identified a number of contributing factors to altitude deviations, such as a pilot’s limited knowledge of a given airspace classification or procedure or errors linked to miscommunications between pilots and air traffic services (ATS) personnel. As reported in a previous issue of the Aviation Safety Letter (ASL), NAV CANADA initiated a national ATS-Pilot Communication Working Group, which includes a variety of aviation stakeholders. The main objective of this group is to identify strategies to reduce the number of miscommunication occurrences between pilots and controllers, which should also have a positive impact on the altitude deviation issue.

Many of the safety issues in aviation are shared responsibilities. In this relatively new era of safety management systems (SMS), we will be in a better position to tackle existing issues and new challenges through the exchange of safety-related information and renewed collaboration between industry partners.


This article was published by Transport Canada in TP 185 Issue 4/2008 -. Reprinted with permission

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