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THE RIGHT NUMBERS FOR SAFETY

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THE RIGHT NUMBERS FOR SAFETY

 

Martin

MARTIN MAURINO, M.ENG Is Safety, Efficiency and Operations Officer at ICAO. He heads the ICAO Cabin Safety Programme. Before joining ICAO, he held safety analysis and safety management roles at Transport Canada and the International Air Transport Association (IATA). Martin began his career in aviation as a cabin crew member at Air Canada.

Cabin crew members play a key role in passenger and operational safety. The number of cabin crew on board, and their performance, are significant factors in the successful evacuation of aircraft. ICAO’s new Manual on the Establishment of Minimum Cabin Crew Requirements (Doc 10072) provides guidance material to ensure the right number of cabin crew members are on board to ensure passenger and operational safety.

As demonstrated from past  accidents, a minimum number of cabin crew members are required on board aircraft to effectively conduct a timely evacuation and increase the survivability of passengers during an accident. ICAO Standards related to minimum cabin crew requirements are found in Annex 6 – Operation of Aircraft, Part I – International Commercial Air Transport – Aeroplanes. The goal of these Standards is to allow for a safe and expeditious evacuation of the aircraft, and to enable cabin crew to carry out the necessary functions to be performed in an emergency or a situation requiring an evacuation.

The ICAO Standards do not provide a numeric value (i.e., an exact number of cabin crew) needed for the operator to comply with Annex 6 requirements. The minimum number of cabin crew members required for each aircraft type in an operator’s fleet must be approved by the State.

How is the number of cabin crew on board calculated?

The number of cabin crew members on board is based on the maximum seating capacity of a specific aircraft type or the number of passengers carried on a particular flight.

Most States use the 1:50 model (i.e., a ratio of 1 cabin crew member to 50 passenger seats installed). This includes the United States and States in the European Union.

This method is based on the aircraft manufacturers’ certificated evacuation capability, as part of the type certificate process. Australia and Canada are examples of States using different models. Canada uses a 1 cabin crew member to 40 passengers on board ratio as a basis.

However, Transport Canada Civil Aviation (TCCA) permits operations with the use of the 1:50 model. Australia requires 1 cabin crew member to 36 passengers on board. However, the Civil Aviation Safety Authority (CASA) may grant permission to large aircraft operators to transition to a 1:50 model if the competent authority is satisfied that an acceptable level of safety can be maintained as a result of implementing this model.

How are these numbers validated?

As part of the type certificate process for a new aircraft type, an aircraft manufacturer must demonstrate that the aircraft, in its maximum seating capacity, can be evacuated within a 90-second timeframe.

Based on these demonstrations, or analysis based on data, aircraft are certified with a minimum number of cabin crew members in relation to a number of passenger seats.

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In order to establish the minimum cabin crew complement, States may require new or existing operators to conduct an evacuation demonstration when a new aircraft type enters their fleet (in addition to the demonstration conducted by the manufacturer).

The goal of this demonstration is to satisfy the State that the operator’s cabin crew members are able to achieve an evacuation and ditching capability equivalent to that achieved for the same aircraft type by the manufacturer.

The number of cabin crew members used by the operator to successfully complete the demonstration is used to establish the minimum cabin crew required on that aircraft type for that particular operator.

Can a cabin crew member manage two emergency exits?

Currently, one of the most-discussed topics in the field of cabin safety is the ratio of cabin crew members to floor-level exits. Operators may comply with the existing ratios but this could result in a cabin crew member being assigned to operate a pair of floor-level exits on certain aircraft types. In addition, some operators attempt to decrease operating costs by reducing the number of cabin crew carried on board, which can also lead to one cabin crew member being assigned two exits.

There are concerns that a single cabin crew member may not be able to manage two exits during a real-life evacuation. On aircraft types where the distance between a pair of floor-level exits is such that a single cabin crew member may not be able to operate or have direct view of the opposite exit, it is highly unlikely that the cabin crew member would be capable of simultaneously giving commands for the two emergency exits, including preventing passengers from opening an unusable exit (e.g., blocked because of fire outside). The crew member would also experience difficulties reaching and operating the opposite exit and managing the evacuation and the passenger flows to both emergency exits of a pair.

CABIN SAFETY EXPERTS WEIGH IN

The ICAO Cabin Safety Group (ICSG) was tasked to assist the Organization in developing the content of Doc 10072. The group was asked to tackle the issue of the number of cabin crew members per floor-level exits. To produce an evidence-based recommendation, the group turned to past accident reports and research.

 

“ICAO recommends that one cabin crew member be assigned per floor-level exit.”

The ICSG reviewed findings from investigations which relate to evacuations, focusing on the number of cabin crew members on board, staffing of emergency exits and impacts on the evacuations and their outcomes. The group also reviewed research on the influence of cabin crew in evacuations and recommendations by aircraft manufacturers.

One of the accidents analyzed occurred in July 1992. A Lockheed L-1011 TriStar 1 on scheduled passenger flight from New York to San Francisco, with 280 passengers and 12 crew members on board, departed the runway after a rejected takeoff at John F. Kennedy International Airport and was destroyed by fire. The evacuation of the aircraft occurred within two minutes. The accident report stated that the speed in evacuating 292 passengers and crew from the aircraft was complemented by the operator’s requirement for nine cabin crew members, which was three more than the minimum required by the State’s regulations … and that the nine cabin crew members were assisted by five off-duty cabin crew members and two off-duty captains who were occupying flight deck jump seats.

Another accident analyzed occurred in August 2005, when an A340-300, on a scheduled passenger flight from Paris to Toronto with 297 passengers and 12 crew members on board, overran the runway after landing at Toronto International Airport. The aircraft caught fire. The accident report stated that applicable regulations called for one cabin crew member for every 50 passenger seats, and the minimum cabin crew requirement for this flight was six crew members. However, there were nine cabin crew members on board; the availability of three supplemental cabin crew members on the accident flight undoubtedly contributed to the success of the evacuation.

In 1994, Cranfield University conducted a study, commissioned by the Civil Aviation Authority of the United Kingdom (UK CAA) and the U.S. Federal Aviation Administration (FAA) on the influence of cabin crew members on passenger evacuations during an emergency situation. Participants were tasked with performing four emergency evacuations in a cabin simulator.

Incentive payments were used to motivate the participants and assist in reproducing the urgency which can occur in an emergency situation. A total of 1,307 participants took part in the evacuation tests. The results showed that the performance and number of cabin crew significantly influenced participant behaviour and evacuation rates.

Based on the review of accident investigations, research studies and manufacturer recommendations, the ICSG concluded that floor-level exits should be assigned to cabin crew members, so that they are attended in the event of an emergency evacuation. The group noted that the presence of cabin crew members at exits is needed to effectively operate them and provide passenger management during an evacuation.

Based on the group’s input, ICAO recommends that one cabin crew member be assigned per floor-level exit, as a means to mitigate the risk associated with unsupervised exits during emergency evacuations.

A SAFETY MANAGEMENT APPROACH TO CREW ON BOARD

Some operators may seek to modify the approved minimum cabin crew complement for specific reasons (e.g., an allbusiness class configuration leading to a reduction in the number of passengers carried).

Although operators may need flexibility, changes must be implemented safely. Therefore, the operator proposing to modify the minimum number of cabin crew on board should demonstrate to the State that there are no significant safety differences between the current cabin safety procedures and the ones for the crew complement being proposed.

The new ICAO manual includes guidance for States to develop a process which should enable them to make an evidence-based decision.

Evidence should consist of a safety risk assessment, operator documentation and a practical demonstration of the proposed changes to validate them. This recommended process provides assurance that an acceptable level of safety is maintained as a result of any proposed change to the number of cabin crew carried on board.

The ICAO Manual on the Establishment of Minimum Cabin Crew Requirements (Doc 10072) is now available to States in English on the ICAO-NET at http://portal.icao.int/ Copies of the accident reports and other documentation can be obtained from the ICAO Cabin Safety Library, at: www.icao.int/cabinsafety

 

Written By MARTIN MAURINO, M.ENG

Published in ICAO JOURNAL – ISSUE 1 2017