Transport Canada's response to the Aviation Safety Recommendations A99-01, A99-02, A99-03, A99-04, A99-05, A99-06, A99-07 and A99-08 issued by the Transportation Safety Board of Canada (TSB)

A98H0003 - Interim Aviation Safety Recommendations for Flight Recorder Duration and Power Supply

Background

On 02 September 1998 at 2118 Atlantic daylight saving time, Swissair Flight 111 (SWR 111), a McDonnell Douglas MD-11 aircraft, HB-IWF, departed John F. Kennedy airport in New York, en route to Geneva, Switzerland. On board were 215 passengers and 14 crew members. Approximately 53 minutes after take-off, as the aircraft was cruising at Flight Level 330, the crew noticed an unusual smell in the cockpit. Within about three and a half minutes the flight crew noted visible smoke and declared the international urgency signal "Pan Pan Pan" to Moncton Area Control Centre, advising the Air Traffic Services (ATS) controller of smoke in the cockpit. SWR 111 was cleared to proceed direct to the Halifax airport from its position 58 nautical miles southwest of Halifax, Nova Scotia. While the aircraft was maneuvering in preparation for landing, the crew advised ATS that they had to land immediately and that they were declaring an emergency. Approximately 20 minutes after the crew first noticed the unusual smell, and about seven minutes after the crew's "emergency" declaration, the aircraft struck the water near Peggy's Cove, Nova Scotia, fatally injuring all 229 occupants on board.

Duration of Cockpit Voice Recorder Information

The CVR installed on SWR 111 employed a continuous-loop magnetic tape of 30 minutes duration. The earliest information on the SWR 111 CVR was recorded approximately 15 minutes before the unusual smell was noted by the crew. Crew conversations and cockpit sounds prior to the beginning of the CVR recording may have provided substantial insight into any initiating or precursor events that led to the accident.

Approximately 38 minutes prior to the unusual smell, Boston Center gave SWR 111 a radio frequency change. During the following 13 minutes Boston Center made repeated attempts to contact SWR 111, without establishing contact. Any cockpit conversations, flight deck noises, or attempted crew transmissions that occurred during this period were subsequently overwritten on the CVR, and therefore could not be assessed.

The 30-minute CVR recording capacity was predicated upon the technology available in the early 1960s; this was the amount of tape that could be crash-protected. The Board is concerned that 30 minutes of recording time is not adequate to capture the initiating events and important background information to many accidents. For example, in accidents involving in-flight fire or progressive structural failure, the initiating events typically develop over a period of time longer than 30 minutes. Longer CVR recording capacity also facilitates the investigation of non-catastrophic occurrences, occurrences in which current 30-minute recordings are often overwritten by the time the aircraft has safely stopped on the ground.

Current technology easily accommodates increased CVR recording capacity. In fact, the majority of newly manufactured solid-state memory CVRs have a two-hour recording capacity, and there is a worldwide industry move towards two-hour CVRs. The European Joint Airworthiness Requirements specify that aircraft first certified after 01 April 1998 be fitted with two-hour CVRs. There is also a proposal to include such a requirement in the Standards and Recommended Practices of the International Civil Aviation Organization (ICAO). The ICAO Flight Recorder Panel, consisting of experts from a number of States, met on 12-20 November 1998, and recommended to ICAO's Air Navigation Commission that aircraft manufactured after 01 January 2003 be fitted with two-hour CVRs.

The TSB is aware that many operators are voluntarily replacing their old technology (tape) data and voice recorders with modern, solid-state recorders. The use of these new recorders not only serves safety but also benefits operators directly, as they avoid the high costs and technical problems associated with maintaining outdated old-technology recorders. Additionally, tape recorders no longer meet the most recent United States Technical Standard Orders (TSO) C123a and TSO C124a crashworthiness standards. This industry trend to solid-state recorders makes it timely to require two-hour CVRs.

A lack of recorded voice and other aural information can inhibit safety investigations and delay or prevent the identification of safety deficiencies. Given the need for longer periods of recorded sound to capture the initiating events of aviation accidents and the availability of two-hour CVRs, the Board believes that such recorders should be mandated by regulatory authorities worldwide. However, it also recognizes that a period of several years may be reasonably required for manufacturers and operators to implement this change. Therefore, for newly manufactured aircraft, the Board recommends that:

As of 01 January 2003, any CVR installed on an aircraft as a condition of that aircraft receiving an original certificate of airworthiness be required to have a recording capacity of at least two hours. (A99-01)

Transport Canada's Response:

Transport Canada fully supports this recommendation and notes that it is similar to an amendment to ICAO Annex 6 proposed by the ICAO Flight Recorder Panel to the Air Navigation Commission. A Notice of Proposed Amendment encompassing this recommendation will be made to the Canadian Aviation Regulatory Advisory Council (CARAC).

Further, the Board believes that, with appropriate lead time, a retrofit program is warranted for aircraft already in service. Therefore the Board recommends that:

As of 01 January 2005, all aircraft that require both an FDR and a CVR be required to be fitted with a CVR having a recording capacity of at least two hours. (A99-02)

Transport Canada's Response:

Transport Canada will introduce an appropriate Notice of Proposed Amendment into the CARAC process. The Department supports this recommendation with the provision that U.S. and Canadian requirements are harmonized.

Independent Power Source

When aircraft power to the SWR 111 flight recorders was interrupted at 10 000 feet, the FDR and CVR stopped recording. The aircraft continued to fly for about six minutes with no information being recorded. This lack of recorded information has hampered the accident investigation.

Power interruptions have resulted in flight recorder information not being captured during the last minutes of several other recent aircraft occurrences. These include ValueJet (Miami, Florida; DC-9-32; 11 May 1996), TWA flight 800 (East Moriches, New York; Boeing 747-131; 17 July 1996), SilkAir (Palembang, Indonesia; Boeing 737-300; 19 December 1997), Delta Air Lines (Cork, Ireland; MD-11; 08 October 1998), and Delta Express (Orlando, Florida, Boeing 737-232; 15 December 1998).

In modern aircraft, flight data and other data from multiple sources are used by the aircraft systems and by the flight crew to operate the aircraft. To record the parameters it needs, the FDR simply monitors the data flowing through data buses. If electrical power to a particular sensor or data bus is lost, FDR information pertaining to that sensor or data bus will no longer be available. In the event of a total loss of electrical power, essentially there would be no data to record. There may be merit in independently powering the FDR and its flight data acquisition unit in order to capture whatever data are available during partial electrical failures. However, as a minimum, the TSB believes the CVR and its cockpit area microphone must continue to be powered for short periods regardless of the availability of normal aircraft electrical power. This independent power source would allow the continued recording of the acoustic environment of the flight deck, including cockpit conversations and ambient noises, for a specific period.

With maintenance-free independent power sources, it is now feasible to power new-technology CVRs and the cockpit area microphone independently of normal aircraft power for a specific period of time in the event that aircraft power sources to the CVR are interrupted or lost. Therefore, to enhance the capture of CVR information needed for accident investigation purposes, the Board recommends that:

As of 01 January 2005, for all aircraft equipped with CVRs having a recording capacity of at least two hours, a dedicated independent power supply be required to be installed adjacent or integral to the CVR, to power the CVR and the cockpit area microphone for a period of 10 minutes whenever normal aircraft power sources to the CVR are interrupted. (A99-03)

Transport Canada's Response:

Transport Canada supports this recommendation with the provision that U.S. and Canadian requirements are harmonized. In their response to a similar recommendation made by the NTSB, the FAA indicated that they would be introducing a Notice of Proposed Rulemaking to amend Technical Standard Order (TSO) 123(a) to address the requirement for a 10 minute independent power supply for CVRs. This TSO is based on a standard developed by the European Organisation for Civil Aviation Equipment, of which Transport Canada is a participating member. The progress of this standard will be monitored and, when appropriate, consideration will be given to introducing this requirement into Canadian legislation.

Separate Electrical Buses

In the current configuration of the MD-11, the FDR and CVR installations are both powered from generator AC Bus No. 3. The MD-11 emergency checklist, dealing with smoke/fumes of unknown origin, requires the use of the SMOKE ELEC/AIR switch. This switch is used to cut power to each of the three electrical buses in turn, in order to isolate the source of the smoke/fumes. The nature of this troubleshooting procedure requires that the switch remain in each position for an indeterminate amount of time, typically at least a few minutes. When the SMOKE ELEC/AIR switch is placed in the first (3/1 OFF) position, generator AC Bus No. 3 and No. 1 air conditioning packs are turned off, thereby simultaneously disabling the FDR and the CVR. Additionally, if the smoke/fumes are cleared in this first position, the SMOKE ELEC/AIR switch is to remain in this position for the duration of the flight, which means that the CVR and FDR both remain inactive while there are data to be recorded. Although it has not been established whether the recorders on SWR 111 stopped as a result of deteriorating electrical systems or the selection of the SMOKE ELEC/AIR switch, the fact that both recorders can be disabled by a single switch selection poses an unnecessary risk of losing critical recorder information.

The Federal Aviation Administration's FAR 25.1457 (CVR) and FAR 25.1459 (FDR), Transport Canada's Canadian Aviation Regulations Standards Part V--Airworthiness Manual, Chapter 551, Articles 551.100 and 551.101, and European Civil Aviation Electronics (Eurocae) specifications require that recorders be installed so that they receive power from the electrical bus that provides the maximum reliability for operation without jeopardizing service to essential or emergency loads. With both the CVR and the FDR on the same generator bus, however, a failure of that bus or the intentional disabling of the bus (as could result from checklist actions in an emergency) result in both recorders losing power simultaneously.

To enhance the capture of information needed for the identification of safety deficiencies, the Board recommends that:

Aircraft required to have two flight recorders be required to have those recorders powered from separate generator buses. (A99-04)

Transport Canada's Response:

Transport Canada, in accordance with CAR 551.01, CAR 605.33 and Airworthiness Manual 551.100, requires the use of separate supply buses. Furthermore, the Transport Canada requirement is harmonized with the EUROCAE-ED-56A by reference.

A98H0003 - Interim Aviation Safety Recommendations - Thermal Acoustical Insulation Materials and Flammability Test Criteria

Background

On 02 September 1998 at 2118 Atlantic daylight saving time, Swissair Flight 111 (SWR 111), a McDonnell Douglas MD-11 aircraft, HB-IWF, departed John F. Kennedy airport in New York, en route to Geneva, Switzerland. On board were 215 passengers and 14 crew members. Approximately 53 minutes after take-off, as the aircraft was cruising at Flight Level 330, the crew noticed an unusual smell in the cockpit. Within about three and a half minutes the flight crew noted visible smoke and declared the international urgency signal "Pan Pan Pan" to Moncton Area Control Centre, advising the Air Traffic Services (ATS) controller of smoke in the cockpit. SWR 111 was cleared to proceed direct to the Halifax airport from its position 58 nautical miles southwest of Halifax, Nova Scotia. While the aircraft was manoeuvring in preparation for landing, the crew advised ATS that they had to land immediately and that they were declaring an emergency. Approximately 20 minutes after the crew first noticed the unusual smell, and about seven minutes after the crew's "emergency" declaration, the aircraft struck the water near Peggy's Cove, Nova Scotia, fatally injuring all 229 occupants on board.

To date, the investigation (A98H0003) has revealed fire damage in the ceiling area forward of and several metres aft of the cockpit bulkhead. While the source of ignition has yet to be determined, there are clear indications that a significant source of the combustible materials that sustained the fire was thermal acoustical insulation blanket materials. Burnt remnants of this material, quenched by the sea water, were found in the wreckage.

Shortcomings related to the in-service fire resistance of some thermal acoustical insulation materials, and shortcomings in the test criteria used to certify those materials, have been identified during this and other recent aircraft occurrence investigations.

Thermal Acoustical Insulation Blanket

Thermal acoustical insulation blankets are widely used in the aviation industry to protect the aircraft interior from temperature variations, noise and moisture. Typically, blanket construction consists of a batt of insulating material encapsulated by a cover or film. Depending on the blanket size required, tape may be used to seal several blankets into a single unit. Selection of cover material is based on factors such as durability, fire resistance, weight, impermeability, and installation considerations. The most widely used cover materials in the aviation industry are metallized polyvinyl fluoride (PVF )⁽¹⁾ and metallized and non-metallized polyethylene terephthalate (PET). ⁽²⁾ The MD-11 involved in this accident was fitted with metallized PET.

The Douglas Aircraft Company first introduced reinforced plastic film insulation coverings during the development of the DC-10. By 1987, the manufacturer (then McDonnell Douglas Corporation) began installing insulation blankets having metallized PET cover material on production aircraft. Further research and development resulted in the use of lighter, non-metallized PET thermal acoustical insulation blankets, which were introduced in 1994 and which superseded metallized PET cover material on new production aircraft. The McDonnell Douglas aircraft produced with metallized PET-covered insulation blankets include the following models: DC-10, MD-80, and MD-11. The total number of aircraft worldwide that have used this material for replacement or repair has not been ascertained. However, it is clear that a large number of aircraft are using, in whole or in part, thermal acoustical insulation blankets incorporating metallized PET cover material.

Metallized PET-covered insulation blankets are used throughout the MD-11 aircraft, including extensive use in the ceiling area forward and aft of the cockpit bulkhead where fire damage has been discovered in the accident aircraft. The investigation has found samples of metallized PET that had been burning. Appendix A provides an overview of some other notable aircraft fires in which metallized PET insulation blanket covering was considered to have aggravated the damage in the occurrence.

In September 1996, prompted by several MD-80 and MD-11 ground fire incidents involving insulation blankets with metallized PET cover material, McDonnell Douglas advised operators to discontinue the use of this material. Additionally, the company stated that it was currently installing non-metallized PET cover material in production aircraft. By 1997 metallized PVF was being used in production aircraft. By October of that year McDonnell Douglas had issued a Service Bulletin (MD-11-25-200) that encouraged MD-11 operators to replace insulation blankets covered with metallized PET material with blankets covered with metallized PVF material. The Service Bulletin also stated that the non-metallized PET cover material that had been used in production aircraft since September 1996 was discontinued, as it did not consistently pass a particular McDonnell Douglas flammability test. That Bulletin also stated that McDonnell Douglas was now using metallized PVF in new production aircraft. Similar Service Bulletins, regarding the use of metallized PET cover material, were issued to DC-8, DC-9, DC-10, MD-80, and MD-90 operators.

Manufacturer's Service Bulletins are advisory in nature unless mandated by the issuance of an Airworthiness Directive by the appropriate regulatory authority.

Thermal acoustical insulation, insulation covering, and insulation blankets must comply with the flammability requirements as described in U.S. Federal Aviation Regulation (FAR) 25.853, Appendix F. In 1997, concerned with the number of incidents involving flame propagation on thermal acoustical insulation blankets, the Federal Aviation Administration (FAA) Research and Development Division conducted a study to evaluate flammability test conditions beyond those called for in Appendix F of FAR 25.853. The study involved testing a variety of insulation blanket cover materials, including metallized PET. The metallized PET samples failed the expanded set of test conditions, prompting the study to conclude that the particular grade of metallized PET cover material used in the evaluation was flammable and possibly could propagate a fire under certain conditions. In March and May 1999 the FAA conducted burn tests as part of its continuing efforts to improve the test criteria required under FAR 25.853 Appendix F. A mock-up was fitted with insulation blanket material to simulate the top part of the fuselage of a commercial aircraft. The preliminary results demonstrated that metallized PET materials could be ignited and that the resulting fires could spread, generating large amounts of smoke under certain conditions and thus exacerbating the emergency associated with an in-flight fire. These results are consistent with observations from the previously referenced in-service fires and other FAA testing results.

With the in-service history, the demonstrated flammability of the metallized PET cover material, and the discovery, in the Swissair Flight 111 wreckage, of remnants of insulating blankets with cover material burnt, it is likely that this material was a significant source of the combustible materials that propagated the fire. It is the Board's view that the operation of aircraft outfitted with thermal acoustical insulation blankets incorporating metallized PET cover material constitutes an unnecessary risk. Therefore, the Board recommends that:

Regulatory authorities confirm that sufficient action is being taken, on an urgent basis, to reduce or eliminate the risk associated with the use of metallized PET-covered insulation blankets in aircraft.  (A99-07)

Transport Canada's Response:

Information received from the Federal Aviation Administration (FAA), indicates that, at this time, the only aircraft manufacturer known to have installed metallized Mylar insulation in production aircraft was McDonnell Douglas Corporation. Based on this information, the FAA issued two Notices of Proposed Rule Making (NPRM) on August 12, 1999. 

NPRM 99-NM-162-AD addresses the removal of metallized Mylar from affected DC-10-30 and -30 F aircraft (manufacturer's fuselage number 440 through 632 inclusive).

NPRM 99-NM-161-AD addresses the removal from affected Model DC-9-81(MD-81),  DC-9-82(MD-82), DC-9-83(MD-83), DC-9-87(MD-87) series; Model MD-90-30 series and Model MD-88 aircraft (manufacturer's fuselage number 1011 through 2241 inclusive).

The NPRMs propose that the metallized Mylar insulation be removed from the affected aircraft within four years. Although there are two operators of McDonnell Douglas aircraft in Canada, none of the Canadian aircraft were produced with the metallized Mylar insulation, therefore, no Canadian registered aircraft would be affected by the proposed Airworthiness Directives.

Bombardier has confirmed that metallized Mylar insulation was not installed in the deHavilland DHC-6, DHC-7, DHC-8, or the Canadair Regional Jet(RJ) series 100 or the Global Express aircraft.

Bombardier has determined that reinforced metallized Mylar tape had been specified for a limited application in the Environmental Control System(ECS)of the RJ Series 700 aircraft. Since the RJ series 700 has not yet been certified nor entered production,  Bombardier is taking steps to alter the design, to remove the metallized Mylar from the aircraft currently being assembled and to dispose of the production supplies of the tape. This will ensure that the RJ series 700 aircraft will enter service without any metallized Mylar insulation blankets or tape.

Transport Canada concurs with the action taken by the FAA to address the potential hazard posed by aircraft produced with metallized Mylar.

The possibility exists that some aircraft that were not produced with metallized Mylar insulation, may have had some metallized Mylar insulation installed during routine maintenance. This issue is being discussed with the FAA and Transport Canada is conducting its own survey to determine if this issue warrants corrective action.

Footnotes

1. Insulation blanket cover material commonly known by the trademark "Tedlar"

2. Insulation blanket cover material commonly known by the trademark "Mylar".

Flammability Test Criteria

The flammability test for thermal acoustical insulation, insulation covering, and insulation blankets, as stated in Appendix F of FAR 25.853, necessitates a vertical flammability test of samples using an approved burner. The type of cover material on the insulation blankets installed on the Swissair aircraft had been subjected to this test and met the applicable flammability test criteria for FAA certification.

In-service fires of the metallized PET cover material, and inconsistent results from the vertical burn test method specified by FAR 25.853, prompted manufacturers to seek additional flammability test criteria. Subsequently, aircraft manufacturers developed a "cotton swab" test, which yielded more consistent results when testing the flammability characteristics of the various cover materials. This additional testing was adopted by several major aircraft manufacturers who subsequently modified their internal material specifications. In 1996, based on results of the "cotton swab" test, McDonnell Douglas advised its customers not to use metallized PET, and discontinued its use in production aircraft. In 1997 an FAA sponsored study confirmed that the "cotton swab" test was a more reliable and reproducible test method to assess the flammability characteristics of metallized PET cover material; however, the FAA did not amend FAR 25.853, Appendix F to improve test standard requirements.

As the incidents listed in Appendix B attest, the limitations of the FAR 25.853, Appendix F, test criteria may not be confined to its inability to accurately and reliably identify the flammability characteristics of metallized PET cover material.

On 14 October 1998 the FAA stated that the test criteria used to certify the flammability characteristics of thermal acoustical insulation materials were inadequate, and committed itself to conducting the research necessary to establish a more comprehensive test standard. At the same time, the FAA indicated that because materials containing polyimide film have performed well in preliminary flammability tests, these materials would be considered compliant under the new regulation. Until adequate flammability test criteria are available, it is not possible to determine whether polyimide film, or other materials, provide adequate protection against fire propagation. Thermal acoustical insulation materials are installed in aircraft as a system, including such related components as tape, fasteners, and breathers. The Board believes that thermal acoustical insulation materials for use in aircraft must be judged against more valid flammability test criteria, not as individual components, but as a system. Therefore, the Board recommends that:

On an urgent basis, regulatory authorities validate all thermal acoustical insulation materials in use, or intended for use, in applicable aircraft, against test criteria that are more rigorous than those in Appendix F of FAR 25.853, and similar regulations, and that are representative of actual in-service system performance.  (A99-08)

Transport Canada's Response:

The authorities including Transport Canada (TC), have already recognized the propensity of certain types of thermal acoustical insulation material systems to spread fire under certain conditions, and the inadequacy of the present flammability test requirements to properly characterize such performance. The authorities have accordingly been working at developing new test standards which will quantify the flammability characteristics of thermal acoustical insulation material systems against realistic fire threats under the environment/conditions to which they are subjected in service, and reliably discriminate between safe and unsafe material systems.

TC has been actively cooperating with the United States Federal Aviation Administration (FAA), as well as Joint Aviation Authorities (JAA) States, in the development of these standards, and associated regulatory material. This work is expected to come to fruition within the next few months.

TC will continue the above work and plans, concurrently with other authorities, to arrive at internationally harmonized solutions to the issue. TC will then proceed with appropriate regulatory action to ensure that thermal acoustical insulation material systems on Canadian-manufactured and Canadian-registered aircraft present safe flammability characteristics.

Further, TC has offered to work with the TSB who plans to explore at the FAA Technical Centre certain thermal acoustical insulation fire propagation theories that could apply to the Swissair MD-11 accident configuration.

APPENDIX A

The following accident synopses represent selected occurrences in which metallized PET insulation blanket cover material was involved.

• 24 November 1993: a McDonnell Douglas MD-87 experienced a fire while taxiing. Initially, the smoke emerged from the aft right side of the cabin. After the passengers and crew had disembarked, the fire intensified dramatically and spread quickly. Investigators determined that the metallized PET-covered insulation blankets acted as fuel sources that helped to spread the fire. [Aircraft Accident Investigation Board, Denmark]

• 06 September 1995: a McDonnell Douglas MD-11 experienced a fire in the Electronics and Engineering bay. Investigators found that molten metal from arcing wires had fallen on metallized PET-covered insulation blankets adjacent to the fuselage skin causing extensive flame propagation and widespread fire damage. [Minister of General Administration of Civil Aviation of China, People's Republic of China]

• 26 November 1995: a McDonnell Douglas MD-82 experienced a cabin fire prior to take-off. A ruptured light ballast case ignited a fire, which spread rapidly with extensive flame propagation on the metallized PET-covered blankets. [Civil Aviation Department, Republic of Italy]

• 08 November 1998: a fire broke out during loading operations of a McDonnell Douglas MD-11. Indications are that a cargo pallet was inadvertently pulled over an electrical cable that supplied power to one of the cable deck floor rollers. A box containing electronic circuitry sparked, which ignited a nearby metallized PET-covered insulation blanket. [National Transportation Safety Board, U.S.]

• 29 March 1999: a McDonnell Douglas MD-11 freighter undergoing maintenance was discovered to have insulation blanket material displaying evidence of fire damage. Preliminary investigation results reveal that chafed wires, located under the floorboards of the aft cargo compartment, had arced, causing nearby metallized PET-covered insulation blanket to ignite. The fire propagated to cover an area of insulation blanket of approximately 60 inches by 26 inches. [National Transportation Safety Board, U.S.]

APPENDIX B

The following accident synopses represent selected occurrences in which metallized PVF insulation blanket cover material was involved.

• 10 October 1994: after landing, ground crew detected a burning smell on a Boeing 737-100. Upon investigation, it was discovered that an improperly installed wire clamp had caused a short circuit. The subsequent arcing ignited nearby insulation blanket that used metallized PVF cover material. [Minister of General Administration of Civil Aviation of China, People's Republic of China]

• 13 November 1995: during a maintenance inspection on a Boeing 737-300 a nut bolt had to be removed using an air drill. This action produced hot metal chips that ignited the metallized PVF insulation blanket cover material under the floor. Flames propagated to consume an area of 18 inches by 40 inches. [Minister of General Administration of Civil Aviation of China, People's Republic of China]

A97H0011 - Loss of Control on Go-around (Rejected Landing) - Air Canada Canadair CL-600-2B19 C-FSKI - Fredericton Airport, New Brunswick 16 December 1997

Synopsis

Air Canada Flight 646, C-FSKI, departed Toronto-Lester B. Pearson International Airport, Ontario, at 2124 eastern standard time on a scheduled flight to Fredericton, New Brunswick. On arrival, the reported ceiling was 100 feet obscured, the visibility one-eighth of a mile in fog, and the runway visual range 1200 feet. The crew conducted a Category I instrument landing system approach to runway 15 and elected to land. On reaching about 35 feet, the captain assessed that the aircraft was not in a position to land safely and ordered the first officer, who was flying the aircraft, to go around. As the aircraft reached its go-around pitch attitude of about 10 degrees, the aircraft stalled aerodynamically, struck the runway, veered to the right and then travelled--at full power and uncontrolled--about 2100 feet from the first impact point, struck a large tree and came to rest. An evacuation was conducted; however, seven passengers were trapped in the aircraft until rescued. Of the 39 passengers and 3 crew members, 9 were seriously injured and the rest received minor or no injuries. The accident occurred at 2348 Atlantic standard time.

Safety Action Taken
(as presented in the TSB report)

Use of Aircraft Anti-Ice

It was discovered during the investigation that operating procedures, combined with the limitations of the ice-detection system, would not ensure that the aircraft wings and engines would be free of ice during flight.

On 11 March 1998, to address the issue of the "ICE" caution being inhibited below the radio altitude of 400 feet agl, Air Canada issued Aircraft Technical Bulletin No. 158 amending the procedures in its AOM (Volume 2/02.00- .02/ .30- .43) as follows:

During flight, the engine cowl and wing anti-ice system must be ON when:

1. icing conditions are indicated by the ice detection system, or

2. there is visual detection of ice formation on the airplane surfaces (windshield wipers, window frames, etc.), or

3. operating below 400 agl and icing conditions exist as defined by the AOM, Vol. 2, 02.17.01, or

4. an ice detector has failed and icing conditions exist as defined by the AOM, Vol. 2, 02.17.01.

Bombardier Regional Aircraft Division, with Transport Canada approval, issued All Operator Message No. 234, dated 20 March 1998, referring to Temporary Revision RJ/61 which was sent to all CL-65 operators. The temporary revision consolidated and clarified icing definitions and procedures for operation in icing conditions, as defined in the Airplane Flight Manual, CSP A-012, to ensure that the ice protection systems are activated whenever the aircraft is operating in conditions that could lead to ice accumulating on the wing and engine cowl leading edges.

The procedures outlined in Air Canada's Aircraft Technical Bulletin and in Bombardier's All Operator Message will reduce the possibility of ice accumulation on the CL-65 aircraft.

Nevertheless, there is still a risk that while an aircraft is operating below 400 feet agl, ice could accumulate to an extent that aircraft performance would be materially affected without the pilots being aware that they had entered icing conditions or that ice had accumulated. If the amber ICE light were not inhibited below 400 feet, however, an extra safe-guard would be in place to alert pilots to the presence of ice.

The Federal Aviation Administration (USA) considers illumination of the amber ICE light to be a warning light, not a caution light. Consequently illumination of the amber light is not inhibited on CL-65 aircraft registered in the USA.

It is acknowledged that illumination of the amber ICE light at low altitude could introduce some risk by distracting the crew; however, this risk must be compared to the risk associated with the increased potential for ice accumulating during a critical stage of flight if illumination of the amber ICE light is inhibited. To reduce the risk of aircraft stall during a critical stage of flight, the TSB issued an Aviation Safety Advisory on 9 April 1999, suggesting that Transport Canada consider taking action to remove the inhibition of the amber ICE light below 400 feet agl on existing and future CL-65 aircraft.

Requirement for an Emergency Locator Transmitter

In reviewing the requirement for Emergency Locator Transmitters (ELTs), the TSB noted that under CAR 605.38(3), multi-engine turbo-jet aeroplanes of more than 5700 kg (12 500 pounds) maximum certified take-off weight, such as the Canadair CL-65, when operating in IFR flight within controlled airspace, over land, and south of latitude 6630' N, are not required to be equipped with an ELT. This "exemption" did not apply to non-turbo-jet aeroplanes (like the Dash-8 and ATR-42) which are similar to the CL-65 in terms of passenger capacity, operational environment, and engine reliability.

TSB information indicates that there is no significant difference in accident rates--between aeroplanes of similar size--strictly as a function of their being turbo-prop versus turbo-jet. Risk mitigation with respect to post-crash survivability that is gained by being equipped with an ELT, such as ELT-assisted search and rescue efforts, applies to all aircraft, regardless of the type of propulsion system.

On 24 February 1998 the TSB issued Aviation Safety Advisory 980004 , suggesting that Transport Canada consider reviewing CAR 605.38(3) with a view to eliminating the ELT carriage exemption for turbo-jet aircraft.

On 3 April 1998 Transport Canada reported that, given the concerns raised in TSB Advisory 980004 and the time interval since the original regulation was promulgated, the General Operating and Flight Rules Technical Committee of the Canadian Aviation Regulation Advisory Council had been tasked to review the adequacy of existing regulation regarding ELT requirements.

Transport Canada has since advised that the Civil Aviation Regulatory Committee, at its 11 December 1998 meeting, decided to initiate amendments to CAR 605.38 to require multi-engine turbo-jet aircraft of more than 5700 kg maximum certified take-off weight operating in IFR flight within controlled airspace to carry an ELT.

Aircraft Low-Energy Issues

When the go-around was initiated, the aircraft was configured for landing, it was at a low height above the runway, the airspeed was decreasing, and the engines were at idle. The aircraft was not able to complete the go-around manoeuvre without ground contact because it was in a low-energy state.

On 13 May 1998 Transport Canada issued a Commercial and Business Aviation Advisory Circular to notify pilots and air operators of the potential hazards associated with a balked landing or go-around. The circular states that an aircraft is not certified to successfully complete a go-around without ground contact once it has entered the low-energy landing regime. For the purposes of the circular, the low-energy landing regime is defined as follows:

1. aircraft flaps and landing gear are in the landing configuration;

2. aircraft is in descent;

3. thrust has stabilized in the idle range;

4. airspeed is decreasing; and

5. aircraft height is 50 feet* or less above the runway elevation.

* Note: 50 feet is a representative value. A given aircraft may enter the low-energy landing regime above or below 50 feet in accordance with approved landing procedures for that type.

The circular further stated that the decision to place an aircraft in the low-energy regime is a decision to land; if there is any doubt regarding the probability of a safe landing, a go-around must be initiated prior to entry into this regime. An attempt to commence a go-around or balked landing while in the low-energy landing regime is a high-risk, undemonstrated manoeuvre. In the extreme case where such action is required, pilots should be aware that ground contact is likely and any attempt to commence a climb before the engines have achieved go-around thrust may result in a stall.

The circular advised that air operators should immediately ensure that their pilots and training personnel are aware of the hazards associated with low-energy go-arounds or balked landings and verify that their training programs address the hazards inherent in, and procedures for dealing with, low-energy operations.

Safety Action Taken
(as presented in the TSB report)

Procedures and Training

Air Canada has taken a number of actions as a result of information learned from this occurrence, as follows:

• the go-around procedure in the CL-65 AOM has been amended to amplify the importance of airspeed during a go-around;

• a NOTE has been added to the CL-65 AOM stating that when a go-around is executed in close proximity to the ground, landing gear ground contact may occur;

• the CL-65 pilot training program has been amended to include information on low-energy go-arounds; and

• the FOM (publication 550), has been amended to include more definitive and conservative requirements regarding low-visibility approaches.

CL-65 Wing Maintenance

In response to the wing surface condition noted on the accident aircraft, Air Canada made some changes to the maintenance of the wings on their CL-65 fleet, to improve their overall condition and, thereby, enhance the aerodynamic performance of the aircraft. These changes supplement the leading-edge maintenance recommended by Bombardier Inc. and consist of the following:

• washing and polishing of the leading edge at 60-day intervals,

• replacing the sealant used on the leading edge with an improved sealant,

• inspecting and restoring the leading edge sealant at each "A" check (every 400 hours),

• repainting wing surfaces as required, based on a C2 segment (2250 hours) inspection.

Safety Information Letters

When an unsafe condition is noted for which remedial action is not immediately required, the TSB staff may draw this to the attention of appropriate regulatory or corporate officials with a safety information letter. These letters are generally concerned with local hazards or with unsafe conditions posing relatively low risks.

Three information letters were sent to Transport Canada regarding TSB observations from this investigation, on the following: flight crew emergency procedures training on the operation of emergency exits; location of emergency equipment, in particular the flashlights; and the provision of signalling tools as part of the survival equipment.

Both Transport Canada and Air Canada have responded to the above-noted safety information letters. A summary of their intended or completed remedial action follows:

• Transport Canada will develop Commercial and Business Aviation Advisory Circulars for air operators, and Policy Letters for Commercial and Business Aviation Inspectors responsible for the approval of flight crew member training programs. These documents are being developed to clarify the intent of the "emergency exits" training requirement, as well as the training requirements for the location and use of emergency equipment, including practical training. Appropriate amendments to the Commercial Air Service Standards will be proposed by Transport Canada.

• Transport Canada will develop a Commercial and Business Aviation Advisory Circular, for air operators, to recommend that on aircraft types where only one flight attendant is carried and the flight attendant seat is located forward, an additional flashlight be carried on that aircraft and that it be located in the rear of the aircraft.

• Air Canada has published Insert No. 72 to their Flight Attendant Manual (Publication 356), regarding the carriage of an additional flashlight in the aft of the CL-65 aircraft.

• Transport Canada advised that they will be establishing a working group to review the current survival equipment regulation and all associated issues and concerns; the TSB's concern regarding a "means for signalling distress" will be included.

Practical Training

During the course of the investigation it was determined that Air Canada's CL-65 Flight Crew Training Program did not provide pilots with the required "hands-on" training on the operation and use of all emergency exits. Transport Canada subsequently responded to a TSB information letter on this issue indicating that action would be taken to enhance operator and Transport Canada inspector awareness of requirements for this training.

Transport Canada's response to the information letter indicated that Transport Canada would take appropriate action to enhance awareness of the requirements for emergency exit training. However, other information from Transport Canada has indicated that a regulatory requirement for "practical training" does not necessarily include direct, "hands-on" training. This indicates that there may be a more wide-spread problem concerning differing interpretations of the meaning of the term "practical training" by Transport Canada inspectors and industry (beyond that applicable to just emergency exits). Differing interpretations by Transport Canada inspectors, or by operators, could result in the associated regulations and standards being applied differently and hands-on training not being provided where intended. Therefore, the TSB issued an Aviation Safety Advisory on 9 April 1999, suggesting that Transport Canada consider taking action to avoid misunderstandings of the meaning of, and requirements for, "practical training.

Safety Action Required
(as presented in the TSB report)

Low-Weather Approaches

The reported weather at Fredericton at the time of the accident was: vertical visibility 100 feet obscured, horizontal visibility one-eighth of a mile in fog, and runway visual range 1200 feet. After the autopilot was disengaged at 165 feet above ground, the aircraft deviated from the desired flight path. The captain subsequently ordered a go-around because he was not sure that a safe landing could be made on the runway remaining. Given the low-energy state of the aircraft, and the crew's uncertainty about the amount of runway remaining, the margin of safety for the flight was significantly compromised.

A review of occurrences involving large aircraft landing in poor visibility was conducted for the period from 1 January 1984 to 30 June 1998. In the United States, there were 18 such occurrences recorded as attributable to poor visibility; most led to aircraft damage and had at least the potential of causing injury to those on board. In Canada, there were 28 such occurrences, the most serious being this occurrence. In only one of the Canadian occurrences was a Category II approach being conducted.

Canadian regulations permit Category I approaches to be flown in visibilities lower than would be permitted in most other countries (including the United States), and the regulations are not consistent with what is recommended in ICAO International Standards and Recommended Practices. ICAO Annex 14 recommends the use of visibility limits whereby pilots are not permitted to carry out an approach if the reported visibility is below the limit specified for the approach. In Canada, however, the visibility values, other than RVR, are advisory only; pilots are permitted to carry out an approach regardless of the visibility, and continue descent to ground level if they have acquired the runway environment. If an airport is RVR equipped, RVR visibility limits do apply in Canada; however, these limits are lower in Canada for a Category I approach than they are in other countries (including the United States). Although an approach for landing is not permitted if the RVR for a runway is below limits, the number of approaches conducted in poor visibility in Canada will likely increase because NAV CANADA is reducing the number of airports served by RVR equipment.

To compensate for the risk associated with landing an aircraft in conditions of low ceiling and visibility, extra aids and defences should be in place. These can take the form of special operating requirements for equipment, training, experience, and procedures. Section 1.18.2.1 of this report details the demanding operating requirements applicable to Category II approaches. As demonstrated by this accident, however, Canadian regulations permit Category I approaches to be conducted in weather conditions equivalent to or lower than Category II landing minima without the benefit of the operating requirements applicable to Category II approaches.

Therefore, to reduce the risk of accidents in poor weather during the approach and landing phases of flight, the Board recommends that:

The Department of Transport reassess Category I approach and landing criteria (re-aligning weather minima with operating requirements) to ensure a level of safety consistent with Category II criteria. (A99-05)

Transport Canada's Response:

The Department has assessed the approach and landing criteria. Draft regulatory amendments to strengthen the standards for instrument low weather approaches will be submitted without delay to CARAC for consultation with the goal of implementing changes as soon as possible.

Low-Energy Go-Arounds

Transport Canada issued a Commercial and Business Aviation Advisory Circular to notify pilots and air operators of the potential hazards associated with conducting a go-around once an aircraft has entered the low-energy landing regime. The circular advised that air operators should immediately ensure that their pilots and training personnel are aware of the hazards associated with low-energy go-arounds and verify that their training programs address these hazards and provide procedures for dealing with them. Dissemination of the advisory circular should reduce the risk of accidents involving low-energy go-arounds in the short term.

Advisory circulars are intended to provide information and guidance regarding operational matters; they do not become a formal part of the safety requirements established by Transport Canada. In the absence of formal entrenchment in the aviation system, these advisory circulars tend to lose their information value as newer circulars on other topics appear. Since the importance of knowledge of low-energy go-arounds will not decrease over time, some process is required to ensure that new pilots are informed of, and experienced pilots maintain their awareness of, the risks involved. Therefore, the Board recommends that:

The Department of Transport ensure that pilots operating turbo-jet aircraft receive training in, and maintain their awareness of, the risks of low-energy conditions, particularly low-energy go-arounds. (A99-06)

Transport Canada's Response:

Transport Canada has issued an advisory to air operators and pilots on the potential hazards associated with an aborted landing or go-around.

Transport Canada will, furthermore, present draft regulatory amendments to include initial and recurrent training in low energy aspects of aircraft operations. It is anticipated that this will be presented to the Part VII Technical Committee of the CARAC for discussion as part of the regulatory development and consultation process as early as December 1999.

Should you require further information, please contact Aviation Safety Analysis at asi-rsa@tc.gc.ca