A92P0191 - Beechcraft A36 BONANZA N6739D Prince George, B.C.18 AUGUST 1992

A92P0191 - Recommendations Concerning In-flight
Opening of Doors on Small Aircrafts

Pre-Flight Inspections

In 30 of the 33 accidents, the "offending" door was apparently not properly secured or was inadvertently left open during pre-flight preparations. As a matter of routine, an aircraft's airworthiness is checked prior to flight by inspecting the security of doors and panels. However, if a pilot becomes distracted or is otherwise inattentive when performing the pre-flight checks, an unsecured door can be overlooked. The occurrence record indicated that improper pre-flight closure of doors continues to be a significant factor in aircraft accident involving inadvertent opening of doors on take-off of in flight.  Therefore, the Board recommends that:

The Department of Transport, through its various safety promotional programs, re-emphasize the need for special vigilance to confirm the security of all doors on small aircraft prior to flight. (A93-06)

Transport Canada Response:

Transport Canada agrees that the need for a properly conducted pre-flight inspection which is essential for a safe flight should be periodically re-emphasized. An article concerning the requirement to ensure the security of cabin and baggage compartment doors prior to flight will be indicated in the 1/94 Issue of the Transport Canada Aviation Safety Newsletter.

Door Latches

Twenty of the 33 accidents involved the opening of a cabin door and six involved a baggage door.  Cabin and baggage door latches used on most small aircraft do not provide a conspicuous visual indication that a door is not secure; nor are these aircraft normally equipped with a “door open” warning device in the cockpit. Apparently, none of the aircraft involved in these accidents had secondary door latches installed.

Secondary latches are normally an optional product enhancement and are designed to prevent aircraft doors from fully opening when the primary latches either fail or are not properly secured. They are available from many aircraft manufacturers or third parties, generally at a relatively low cost. Some secondary latches provide a much better visual indication of unsecured doors than to the primary latches.

In order to enhance the visual conspicuity of improperly secured doors, the Board recommends that:

The Department of Transport encourage manufacturers of small aircraft to incorporate primary door latches which will provide a conspicuous visual indication of unsecured doors; and, (A93-07)

The Department of Transport promote the use of secondary door latches, especially those which provide a conspicuous visual indication if unsecured. (A93-08)

Transport Canada Response:

A review of the design standards (FAR 23) shows that requirements for direct visual inspection of the door locking mechanism and cockpit warning of external unsecured doors was introduced for commuter category airplanes in 1987. In 1988 this was expanded to include external doors forward of any engine or propeller and for any doors for which the initial movement is not inward on normal, utility and aerobatic category aircraft.

The Department contacted the three largest manufacturers of small aircraft in the United States and has confirmed that they have, in many cases, developed latches with visual indications of insecurity and fitted them to their aircraft or offered them as optional equipment. Transport Canada is satisfied that the manufacturers are fully aware of the door opening problem and are taking reasonable steps to address it.

Transport Canada will, however, encourage the operators to ensure the maintenance standards are adhered, to in order to eliminate the problem of inadvertent door openings in-flight. A Service Difficulty Advisory will be issued to warn the operators of the hazards of inadvertent door openings, and to advise them of the commercial availability of add-on kits to install secondary latches as well as the visible indications of insecurely latched doors.

In-flight Procedures

An open door in flight can generate extensive noise, airframe buffeting, loss of lift, increased drag, and adverse aircraft stability.  In the data sample, all 33 aircraft should have been capable of controlled flight with the door open. However, the distraction, pre-occupation, channelized attention, panic, etc. associated with a door opening in flight apparently affected 17 of the accident pilots to such an extent that aircraft control was significantly degraded. This resulted in the pilots either stalling the aircraft, landing wit the gear up, landing hard, inadvertently flying into the ground or an object, or losing control of the aircraft while attempting to close the door. In 11 of these 17 accidents, the pilot-in-command had over 500 hours total flying time.

A pilot who is not mentally prepared for an unfamiliar situation such as a door opening in flight, may take inappropriate actions to deal with the situation.  The stress inherent in such emergencies could cause pilots to narrow their normal scanning pattern, resulting in failure to monitor critical flight parameters or to perform essential actions.

Individuals are less susceptible to distraction-induce4d errors and erroneous decision-making if they are prepared for an emergency or unusual event by having a pre-determined plan of action.  Guidance on the handling of open doors on take-off or during flight is not consistently provided to pilots during initial training, nor is such training required by regulation. The study and reference materials currently used by student pilots provide little discussion on this subject. Likewise, Transport Canada's publications and promotional activities do not provide significant guidance to licensed pilots.

In view of the frequency of accidents where the pilot response to the inadvertent door opening was inadequate, the Board recommends that:

The Department of Transport ensure that the general guidance concerning the handling of doors opening on take-off or during flight be provided to:

  1. student pilots during ab initio training; and
  2. licensed pilots during re-current training through reference publications and safety promotional programs. (TSB A93-09)

Transport Canada Response:

Transport Canada agrees that the information available to pilots on how to handle this type of emergency should be enhanced.  The Department will provide additional guidance to student pilots and flight instructors as well as ensuring that licensed commercial pilots are checked on their knowledge of this problem.

The fourth edition of the Flight Training Manual (FTM) for aeroplanes is being amended and plans are to publish it in the spring of 1994. This edition will include additional text on this subject under the heading of flight preparation and a new section on emergencies will provide general guidance on handling this problem. When the recently published training manual for helicopters is re-issued, information and guidance on this subject will be included in the appropriate exercises.

The periodic publication “Post Flight”, which is distributed to all flying clubs and schools, Designated Flight Test Examiners (DFTE) and Flight Training Standards Inspectors (FTSI) will feature an article on this topic in the September 1993 issue. As well, this subject will also be included for discussion at forthcoming Instructor Refresher courses and at DFTE and FTSI workshops scheduled for completion by March, 1994, and during the on-going Flight Training Evaluation Team visits.

Regional inspectors will be directed to add, where appropriate, the evaluation of in-flight door opening emergency procedures when conducting Pilot Proficiency checks on pilots operating under ANO Series I, No. 2. The operators involved in the transportation of passengers under this Order will be sent an information letter outlining the TSB recommendations and which will strongly suggest their approved training programs be updated with respect to the procedures for handling the in-flight opening of doors, hatches and panels.

An Air Carrier Advisory Circular will be sent to commercial operators of small aircraft and rotorcraft on accidents involving the in-flight opening of doors windows and panels. This circular to ANO Series VII, No. 3 and No. 6 operators will ask them to review the hazards associated with the distraction and pilot preoccupation when his emergency occurs. The operators, Transport Canada and other examiners will be asked to consider, in this review, how an open door can generate excessive noise, airframe buffeting, loss of lift, increase drag and lead to instability and control problems. 

Aircraft Flight Manuals

The flight characteristics of an aircraft with an open door vary by aircraft type; consequently, type specific procedures may be required in order to land safely with an open door.  Some manufacturers already provide specific procedures in their safety supplements; however, the pilots' primary reference document, the Aircraft Flight Manual (AFM), normally does not contain this type of information.  In order to improve the availability to information for pilots to safely handle the opening of doors on take-off or in flight, the Board recommends that:

The Department of Transport encourage manufacturers of small aircraft to include specific guidance in Aircraft Flight Manuals on the handling of inadvertent door opening on take-off or in flight. (TSB A93-10)

Transport Canada Response:

Transport Canada agrees that guidance should be provided if the inadvertent opening of a door or a hatch will create an unusual hazard that is specific to an aircraft type. A survey of manufacturers indicated that they are very much aware of the door opening problem and have included door re-closing instructions in the Aircraft Flight Manual where it is safe to do so.

Existing regulations require that the pertinent information necessary for the safe operation of the aircraft be provided under normal and emergency circumstances. The Aircraft Flight Manual (AFM) would be required to address inadvertent openings of doors or hatches if such an occurrence would require special procedures that are specific to that aircraft.

The accidents that were reviewed for these recommendations did not indicate that the handling characteristics of the aircraft with the door open or lost was degraded. There is no indication that any particular aircraft type requires an amendment to address handling with door(s) open. Changes to the flight manual are not advisable unless flight testing or service experience identifies adverse flight characteristics which would require specific operating procedures.

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