Jump to Content

Cross-crew qualification and mixed fleet flying

Issue number: AO-2009-012-SI-02
Who it affects: Flight crews
Issue owner: Airbus, Flight Safety Foundation, International Air Transport Association
Operation affected: Aviation: Air transport
Background: Investigation Report AO-2009-012
Date: 19 December 2011

Safety issue description

The available Cross Crew Qualification and Mixed Fleet Flying guidance did not address how flight crew might form an expectation, or conduct a ‘reasonableness' check, of the speed/weight relationship for their aircraft during takeoff.

Background

The problem experienced by the flight crew in determining the ‘reasonableness’ of the take-off performance figures that were calculated by the electronic flight bag is not unique to this accident. Previous investigations into similar data entry error and tailstrike occurrences have highlighted the inability of flight crew to conduct a ‘rule of thumb’ or reasonableness check of their take-off speeds.

Furthermore, an unintended consequence of mixed fleet flying appears to be a reduction in a flight crew’s ability to build a model in long-term memory to facilitate recognition of ‘orders of magnitude’ or ‘rules of thumb’ in respect of take-off performance data. That is, the effect of mixed fleet flying appears to exacerbate the difficulty already being experienced by crews in discerning the appropriateness of their aircraft’s performance.

Indeed, because performance figures that are quite reasonable for one variant may not be reasonable for another variant, affected flight crew would need to build a model for each aircraft variant experienced. Currently, there is no specific guidance to assist flight crew to form those mental models in respect of the weight and corresponding take-off performance parameters for a particular aircraft variant.

Safety Advisory Notice

Action organisation: Flight Safety Foundation
Action number: AO-2009-012-SAN-086
Date: 19 December 2011
Action status: Closed

The Australian Transport Safety Bureau requests that the Flight Safety Foundation consider developing guidance to assist flight crews form appropriate mental models in respect of the weight and corresponding take-off performance parameters for a particular flight. The use by operators of mixed fleet flying increases the importance of that guidance.

Safety Advisory Notice

Action organisation: International Air Transport Association
Action number: AO-2009-012-SAN-087
Date: 19 December 2011
Action status: Closed

The Australian Transport Safety Bureau requests the International Air Transport Association to encourage its members to develop guidance to assist their flight crews form appropriate mental models in respect of the weight and corresponding take-off performance parameters for a particular flight. The application by operators of mixed fleet flying increases the need for that guidance.

ATSB response:

Date: 19 December 2011

The ATSB recognises that the existing avionics technologies have as yet been unable to develop a take-off monitoring and alerting system. However, given that equipment unavailability, the ATSB remains concerned at the present lack of take-off performance monitoring guidance available to flight crews who are involved in mixed fleet flying. In that context, consideration was given to the most effective means of promoting relevant safety action among the world’s operators.

Ultimately, that means of communication was determined to be via a safety advisory notice (SAN) that sought the assistance of the International Air Transport Association (IATA) and Flight Safety Foundation (FSF). The intent was that those organisations would, through their members, be best equipped to address the safety issue. Hence, the ATSB issues the following SANs to IATA and the FSF.

Proactive Action

Action organisation: Airbus
Action number: AO-2009-012-NSA-088
Date: 15 December 2011
Action status: Closed

In July 2009, Airbus announced in their Safety First magazine that they were developing a software package called the ‘Take-off Securing’ (TOS) function. The TOS function automatically checks the data being entered into the flight management and guidance system (FMGS) for consistency between the take-off parameters.

A check is carried out on the takeoff reference speeds entered into the FMGS against take-off limitation speeds calculated within the FMGS based on the aircraft weight. If the TOS function detects a discrepancy between these speeds, it alerts the flight crew by displaying a message on the FMGS display unit. On 28 May 2010, Airbus provided the ATSB with the results of a simulation of the TOS function for the A340 using the accident flight take-off performance parameters. The result is shown below [image of results showing "TO SPEED TOO LOW" warning in scratch pad]. On 28 October 2011, Airbus advised that they plan an additional development that will include functionality to check that the aircraft has sufficient runway length to support a safe takeoff.

ATSB response:

The ATSB is satisfied that when installed in transport aircraft, the Take-off securing function will adequately address this issue.

   
Current issue status: Partially addressed
Status justification:

The Flight Safety Foundation has commenced education (initially through AeroSafety World article). There is no more that the ATSB can directly do until engineered systems are implemented and the appropriate experts (not based in ATSB) find solutions to the Human Factors side of it.

 
Share this page Comment
Last update 31 January 2014