Airworthiness Function or Check flights are a special type of flight carried out periodically by many operators. All will require, at the very least, a special pre-flight briefing and some will be sufficiently complex and at variance with normal line flying to require that flight crew conducting them are specifically trained for the task.
Defining the Pilot Training Need
Flight crew employed by aircraft operators are trained to deliver safety, efficiency and comfort during line operations. Their training is focused on developing and sustaining the necessary knowledge, flight management and aircraft handling skills to conduct normal operations and to safely deal with the unexpected problems which may arise from malfunctions, weather challenges, the actions of others or the consequences of their own unintended actions. The various types of airworthiness function or check flights which an operator may need or elect to conduct vary considerably in their degree of complexity. However, unlike many test flights carried out by specially trained test pilots, these are carried out following a normal technical 'Release to Service' recorded in the Aircraft Technical Log. Operators may conduct function or check flights:
- As the first flight after significant scheduled or unscheduled maintenance including repainting
- To allow engineers to examine the nature of a recorded defect prior to rectification
- To validate the operational status of an aircraft before acceptance from or return to a lessor for contractural reasons.
Only the third category of flight listed above is normally a formal requirement, and is certainly a sufficiently challenging task to require discrete recognition in provisions of the operator's Safety Management System (SMS). It is likely to involve a check schedule which entails operation of various aircraft systems in intentionally degraded states where the potential consequences and responses need to be fully appreciated. The other two cases mainly involve being prepared for the unexpected whilst operating the aircraft normally and are usually carried out on the basis that they are good operational practice. Whilst they are not like normal line operations, most operators will be content to authorise selected check/training captains, or sometimes experienced line captains, to command such flights. However, the operator’s SMS must also recognise and address these other variations from line operations and determine whether any specific process for crew selection and initial and recurrent training is required.
Meeting the Pilot Training Need
As a result of a succession of accidents and incidents arising from a steadily increasing number of airworthiness function / check flights, it has become clear that formal supplementary training is needed for flight crew expected to conduct the more demanding types of such fights. In the past, this training has not been supported by aircraft manufacturers and has been left to the discretion of operators with in many cases little, if any, intervention from the regulatory agencies who oversee the Air Operator Certificate (AOC) holders. A notable exception to this has been the availability of the UK CAA Check Flight Handbook. This mindset is now beginning to change and aircraft manufacturers (notably Airbus) are applying their unique expertise, gained from test flying by qualified test pilots on new and pre-delivery aircraft, to develop training courses which will equip selected line pilots to carry out airworthiness function / check flights, both as an aircraft commander and as a co-pilot. In respect of the latter, recent experience has demonstrated that co-pilot ability to carry out an effective monitoring pilot (PM) role, and thereby support the safe conduct of the flight, has been severely limited by both their level of understanding of aircraft systems and the often steep authority and knowledge gradient between the two pilots.
A Typical Pilot Training Course Syllabus
Classroom training should cover the following:
- Crew responsibilities and task sharing
- Flight preparation and authorisation
- Pre-flight briefing
- Recording of in-flight parameters
- Risk Management - operational and safety aspects of flight check profile and risk mitigation.
- Aircraft-type specifics and use of special system checklists in flight
Full flight simulator training should provide demonstration and practice of representative system test sequences and possible outcomes. The importance of adherence to all applicable manufacturers’ recommended flight check profiles should be stressed and, where appropriate, demonstrated.
A typical manufacturer course is the Technical Flight Familiarisation Course offered by Airbus which may be run at the manufacturer's premises or at the Operator's base and is a five day course consisting of 3 modules:
- A two-day ground school
- Two, four-hour full flight simulator sessions to:
- train key checks in normal operations
- analyse some abnormal situations
- One four-hour flight in an aircraft to train key procedures.
The role of observing engineers
Manufacturers, such as Airbus, typically recommend that all flights where aircraft systems will be intentionally degraded should be carried out with an appropriately qualified and experienced aircraft engineer (or alternatively a third pilot who has been trained to the same level as the designated aircraft commander) occupying one of the flight deck supernumerary seats. The role of this third person should be clearly defined in relation to the primacy of the operating flight crew and the aircraft commander in particular.
The operating crew and any other personnel legitimately on the flight deck for an airworthiness function / check flight are the final line of defence in risk management, where the principal risk is loss of control. Useful background perspective on the importance of employing suitably trained flight crew on such flights is contained in the official Reports of two Accident / Serious Incident Investigations. See:
- B737, manoeuvring, west of Norwich UK 2009 - A Serious Incident involving loss of control to a Boeing 737 being operated by UK airline Easyjet whilst on an airworthiness function flight required by lessor handback procedures in 2009
- A320, vicinity Perpignan France, 2008 - A fatal accident to an Airbus A320 being operated by XL Airways Germany following loss of control during an airworthiness check flight following repainting in preparation for lessor handback in 2008
Flight Safety Foundation
- Functional Check Flight Compendium - This paper deals with the important subject of how to prepare and conduct functional check flights. It includes causes of upsets during check flights and the recovery methods from such upsets are discussed, but the coverage is deliberately limited to the check flight situation and is not intended to be a paper on the whole subject of upset training and recovery.