Aviation Investigation Report A98H0003
- 126.96.36.199 - General
- 188.8.131.52 - Flight Crew Smoke/Fumes Checklists
- 184.108.40.206 - Swissair MD-11 Checklist Design
For emergency procedures, each pilot had available in the cockpit, a book of checklists entitled Emergency Checklist Alert and Non-alert. The following three flight crew checklists dealt specifically with smoke or fumes:
- Air Conditioning Smoke (see Appendix B Swissair Air Conditioning Smoke Checklist);
- Smoke/Fumes of Unknown Origin (see Appendix C Swissair Smoke/Fumes of Unknown Origin Checklist); and
- Smoke/Fumes Removal.
For smoke and fire emergencies, checklist procedures were available for the cabin crew in the Cabin Emergency Preparation/Evacuation Checklist. (STI1-103) These procedures were entitled "Smoke On Board" and "Fire On Board."
The MD-11 was certified with the following three flight crew checklists for identifying and dealing with smoke/fumes: Air Conditioning Smoke; Smoke/Fumes of Unknown Origin; and Smoke/Fumes Removal. The aircraft manufacturer recommended that the Air Conditioning Smoke checklist be used only when a flight crew was certain that the air conditioning system was the source of smoke or fumes.
In March 1993, the aircraft manufacturer removed the Air Conditioning Smoke Checklist from the Flight Crew Operating Manual (FCOM), although it was retained in the FAA-approved Airplane Flight Manual (AFM). The Smoke/Fumes of Unknown Origin Checklist was renamed to the Smoke/Fumes of Electrical, Air Conditioning, or Unknown Origin Checklist. The amendment was based on the logic that the same steps were included in the Smoke/Fumes of Unknown Origin Checklist; therefore, regardless of the source, the same action items could be used to attempt to isolate the source of the smoke/fumes.
Swissair developed its MD-11 checklists based on the FAA-approved AFM. When the aircraft manufacturer reduced to one smoke/fumes checklist in the FCOM, some airline operators including Swissair, decided to keep the two separate checklists. The Swissair decision to keep the two checklists was based on the view that if a flight crew could determine, with 100 per cent certainty, that the air conditioning system was the source of smoke/fumes, the Air Conditioning Smoke checklist would be used and there would be no associated disruption to the aircraft electrical system. Swissair considered this to be the safest alternative, because when the Smoke/Fumes of Unknown Origin Checklist is actioned, electrical power and pneumatics are removed from a number of services (see Appendix C), making it more demanding to fly the aircraft.
The source document for MD-11 checklists used by Swissair crews is the Swissair MD-11 AOM. This manual, developed by Swissair, describes the MD-11 aircraft systems and normal, abnormal, and emergency operating procedures. The AOM was derived from the FAA-approved AFM, the McDonnell Douglas MD-11 FCOM and Swissair's company policies. Revisions to the AOM were issued to manual holders as required from time to time and distributed by means of a consecutively numbered "Transmittal Letter." AOM bulletins were periodically published to inform manual holders of technical/operational matters related to the AOM including checklist revisions. The AOM and revisions were submitted to the FOCA for review; checklist revisions are not required by the JARs to be approved by the FOCA. AOM bulletins are submitted to the FOCA for information only.
Swissair's checklist design philosophy considered ease of use, accessibility, brevity, and similarity in groupings. Checklists were to be designed to be simple in presentation, especially those pertaining to emergency situations, and were to be quickly and easily accessible by the flight crew. Each procedure, from start to finish, was to be designed to be contained on one page; procedures having common themes were grouped together.
Swissair maintained a close relationship with the manufacturer concerning checklist design. They met regularly to discuss such matters as potential checklist changes and problems noted with checklist usage during simulator sessions; however, the manufacturer does not approve the checklists used by the operators.
An FAA document entitled Human Performance Considerations in the Use and Design of Aircraft Checklists was published in 1995 to assist FAR Part 121 and 135 operators in the design, development, and use of cockpit checklists, and to increase their awareness of human performance issues relating to checklist usage. The CAA in the United Kingdom has a similar set of guidelines, entitled Guidelines for the Design and Presentation of Emergency and Abnormal Checklists.
Although these guidelines were not in effect during the MD-11 design period, they were available for reference during ongoing checklist modifications. As part of the SR 111 investigation, the guidelines were used to evaluate the Swissair emergency checklist dealing with smoke/fumes.
Deviations from the guidelines were noted. While the one-page principle is appropriate in general, its application for the Smoke/Fumes of Unknown Origin Checklist conflicted with other design principles. For example, attempts to condense this checklist onto one page led to the use of smaller-than-recommended font sizes in the notes section.
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