Air transportation safety investigation report A98H0003
Appendices
Appendix A – Flight profile: Selected events
Appendix B – Swissair air conditioning smoke checklist
Appendix C – Swissair smoke/fumes of unknown origin checklist
Appendix D – Timeline
This timeline is a chronological summary of the factual information provided in Section 1 of the occurrence report. The timeline contains significant events and selected anomalies from the aircraft flight recorders (CVR/FDR), ATS communication tapes, ATC radar, FADEC non-volatile memory, and ACARS.
| UTC Time | Events |
|---|---|
| 2318:55 | The ACARS system of SR 111 logged onto the network while the aircraft was at the gate at JFK airport in New York. |
| 2330:18 | The SATCOM system of SR 111 logged onto the network while the aircraft was at the gate at JFK airport in New York. |
| 0018 | SR 111 departed JFK airport in Jamaica, New York. |
| 0019:46 | The flight crew of SR 111 requested a heading deviation from the cleared track to avoid the isolated thunderstorms in that area. |
| 0033:12 | The last communication from SR 111 prior to the 13-minute gap, when the captain acknowledged a radio frequency assignment change from Boston ARTCC (124.52 MHz to 128.75 MHz). |
| 0033:21 | The FDR recorded a VHF 1 microphone keying event that would be consistent with the flight crew attempting to contact Boston ARTCC. No transmission from SR 111 was heard on frequency 128.75 MHz or on any other recorded ATS frequency. |
| 0033:21 to 0045:39 |
The FDR recorded 11 microphone keying events by SR 111 during the 13-minute gap, 9 on VHF 1 and 2 on VHF 2. During this time, Boston ARTCC attempted to contact SR 111 four times on the assigned frequency of 128.75 MHz, three times on the previous frequency of 124.52 MHz, and at least once on the aviation emergency frequency of 121.5 MHz. None of the 11 keying events from the aircraft coincided with the times of the transmissions from Boston ARTCC, indicating that the SR 111 crew was not likely receiving the ATS radio calls. |
| 0046:27 | SR 111 called Boston ARTCC using VHF 1 on 134.95 MHz, a frequency that had not been assigned to the flight. This transmission was recorded on the ATS tape; however, the Boston ARTCC controller did not comprehend the call that was made on an unassigned frequency and did not immediately respond to this first SR 111 call. |
| 0047:02 | The FDR indicates that SR 111 attempted another brief call on VHF 1 on an unknown frequency. |
| 0047:03 | INMARSAT logs show a downlink from SR 111 indicating that VHF 3 data communications were lost. |
| 0047:15 | SR 111 again called Boston Center using VHF 1 on 134.95 MHz. |
| 0047:18 | Communications with SR 111 was restored when Boston ARTCC heard and acknowledged this transmission, and instructed SR 111 to switch to the appropriate frequency for the area control sector they were in (133.45 MHz). |
| 0048:12 | Two-way communications were then restored, and the controller and SR 111 could hear each other clearly. There is no record of either the pilots or the controllers at Boston ARTCC making any further comments about the gap in communications. |
| 0053:17 | The CVR recording began. |
| 0053:51 | INMARSAT records indicate that there was a downlink from SR 111 confirming that VHF 3 communications had been lost for more than seven minutes. |
| 0058:13 | SR 111 contacted Moncton ACC and reported that they were at FL330. |
| 0104:14 | The ACARS MU sent a downlink message changing coverage from INMARSAT back to ARINC. |
| 0110:38 | The first officer referenced an unusual odour in the cockpit. |
| 0110:57 | The captain said "look," indicating something was visible in the cockpit. |
| 0111:14 | Having been given permission to stand up at 0111:06, the first officer transferred flying control of the aircraft to the captain. |
| 0111:29 | The first officer indicated that there was nothing more "up there." |
| 0112:06 to 0112:17 |
The captain summoned to the cockpit a flight attendant working in the first-class cabin. A few seconds later, she opened the cockpit door and entered the cockpit. In response to a query from the captain, the flight attendant indicated that she could smell the odour in the cockpit, but had not noticed any odour in the cabin where she was working. No references were made to visible smoke at this time. |
| 0112:24 | Based on the comment by the captain, it appears that wherever the smoke may have been originally spotted, the amount was likely small, momentary in nature, and no longer visible. |
| 0112:26 | Sound of electric cockpit seat moving (two seconds duration). |
| 0112:32 | The captain commented: "Air conditioning, is it?" The first officer answered "yes." |
| 0112:35 | The captain indicated that something should be closed; most likely he was requesting that the flight attendant close the cockpit door. |
| 0112:37 | Sounds consistent with the cockpit door closing were recorded. |
| 0112:44 | Sound of electric cockpit seat moving (two seconds duration). |
| 0112:52 | The FDR recorded that the Air Page was selected on the system display. (This selection could have been made anytime within the previous 63 seconds and would not have been immediately recorded by the FDR because of the 64-second sample rate interval for recording this FDR parameter.) |
| 0112:54 | The seat belt lights were activated in reaction to light turbulence being experienced. |
| 0113:13 | The flight crew successfully requested weather information via ACARS. |
| 0113:14 | At some location in the cockpit, a discernable amount of smoke again became visible to the pilots. |
| 0113:33 | The pilots considered potential diversion airports and the need to bring the navigation charts forward from the ship's library. Weather conditions were considered in the assessment of various destinations. |
| 0113:53 | The captain commented "That's not doing well at all up there." |
| 0114:05 | The captain attempted to call Moncton ACC, but the radio transmission was blocked by a simultaneous transmission from another aircraft. |
| 0114:15 | SR 111 made a Pan Pan radio transmission to Moncton ACC. The aircraft was about 66 nm southwest of Halifax International Airport, Nova Scotia. The flight crew indicated that there was smoke in the cockpit and requested an immediate return to a convenient place. The flight crew named Boston, Massachusetts, which was about 300 nm behind them. |
| 0114:31 | The Moncton ACC controller immediately cleared SR 111 to turn right toward Boston. |
| 0114:37 | The flight crew successfully requested weather information via ACARS. |
| 0114:43 | The Moncton ACC controller cleared SR 111 to descend to FL310. |
| 0114:48 | The captain's oxygen mask was removed from its stowage box, and the sound of oxygen flowing from the mask was evident. |
| 0115:06 | The controller asked the pilots whether they would rather go to Halifax. |
| 0115:10 | Having identified Halifax as the closest airport, it was chosen. Halifax was a Swissair-designated intermediate alternate airport, and therefore was approved for MD-11 operations. |
| 0115:29 | The first officer was reassigned the flying duties and instructed to descend immediately. |
| 0115:36 | The captain advised the controller that they would prefer Halifax. |
| 0115:41 | SR 111 was cleared by the controller to proceed directly to Halifax and to descend to FL290. At this time, the aircraft was at FL328, about 56 nm from the threshold of Runway 06. |
| 0115:56 | The captain donned his oxygen mask. |
| 0116:03 | The first officer donned his oxygen mask. |
| 0116:05 to 0117:04 |
Moncton ACC was coordinating the arrival of SR 111 with Halifax tower via land line. |
| 0116:08 | The Halifax weather information was passed to SR 111 by the crew of an overflying aircraft. |
| 0116:34 | The controller cleared SR 111 to descend to 10 000 feet. |
| 0116:50 | The Moncton controller asked SR 111 for the amount of fuel and the number of passengers on board so that he could pass the information to the Halifax Aircraft Firefighting Services through Halifax tower personnel. SR 111 told the controller to "stand by" for that information. |
| 0117:19 | The aircraft passed through FL297 and the speed brakes were fully extended. The rate of descent increased to 4 000 fpm, and then reduced to about 3 500 fpm by 0119:28. |
| 0117:20 | The instrument approach plates for the Halifax airport were not readily available to the pilots to provide readily accessible information about the runway, safety altitudes, and published approach details. |
| 0117:16 to 0118:20 |
Based on the FDR sample rate intervals, it is known that the selected airspeed was changed from 292 KIAS to 310 KIAS. |
| 0117:38 | The captain indicated to the first officer that he should not descend too fast, likely referring to the airspeed that was being selected at that time rather than the aircraft's rate of descent. |
| 0117:50 | The captain briefed the M/C that there was smoke in the cockpit, that the cabin crew was to prepare for landing in Halifax in about 20 minutes to half an hour, and that he was about to start a checklist. |
| 0118:17 | SR 111 was directed to change to Moncton Centre frequency 119.2 MHz. The first officer, who continued as the pilot flying, was also assigned the radio duties. |
| 0118:44 | The controller cleared SR 111 to 3 000 feet. The pilots requested an intermediate altitude of 8 000 feet while the cabin was being prepared for landing. |
| 0119:12 | The controller asked the SR 111 flight crew whether they would like radar vectors to Runway 06 at Halifax. |
| 0119:16 to 0119:28 |
The first officer asked for the latest wind information. The controller did not relay the wind information, but repeated that Runway 06 was the active runway and asked whether he should start the radar vectors. SR 111 accepted radar vectors for Runway 06 and the controller instructed the aircraft to turn left to a heading of 030. |
| 0119:27 | The captain had been attempting to contact a flight attendant directly for some time. A flight attendant entered the cockpit and moved the crew bag containing the approach chart information to within the captain's reach. |
| 0119:37 | The controller informed SR 111 that the instrument approach to Runway 06 was a back-course (backbeam) approach. He provided the localizer frequency, and advised the flight crew that they were 30 miles from the threshold of Runway 06. |
| 0119:50 | The first officer informed the controller that more than 30 miles would be required. The aircraft was 30 nm from the threshold of Runway 06, descending at about 3 300 fpm through FL210, at an airspeed of 320 KIAS. |
| 0119:57 | SR 111 was instructed to turn to a heading of 360 degrees, to lose altitude. |
| 0120:14 | An announcement was made by the M/C to the passengers, informing them that the aircraft would be landing in Halifax in 20 to 25 minutes. |
| 0120:15 | The pilots agreed that a quick descent was warranted in case the smoke thickened. |
| 0120:31 | The first officer asked the captain whether he agreed with conducting a backbeam approach to Runway 06, indicating that it would be the quickest approach and would result in landing into wind. |
| 0120:48 | The first officer also mentioned fuel dumping and asked the captain about his preference for where and when to dump fuel. The captain seemed to concur; however, his verbal response to these inquiries was interrupted by a physical activity involving stretching, consistent with retrieving something that was out of normal reach, perhaps a checklist or an approach chart. |
| 0121:20 | The controller requested the number of persons and the amount of fuel on board. |
| 0121:27 | The first officer responded that there was 230 tonnes of fuel on board; this was actually the current gross weight of the aircraft, not the weight of the fuel alone. He did not relay the number of persons on board. He queried the controller about whether fuel dumping could be done in that area during descent. |
| 0121:38 | The controller responded by asking whether SR 111 was able to turn back to the south, or whether they wanted to stay closer to the airport. |
| 0121:46 | When conferring about this with the captain, the first officer stated that the controller would prefer that fuel dumping be done to the south, and asked the captain whether they should do that or whether they should go and land. Given their understanding of the current situation, the pilots decided that turning to the south for fuel dumping would be appropriate. |
| 0121:56 | The first officer informed the controller that a left or right turn toward the south was acceptable. |
| 0122:01 | The controller instructed SR 111 to turn left to a heading of 200 degrees, requested that the pilots indicate when they were ready to dump the fuel, and advised them that it would be about 10 miles before they were off the coast. He advised SR 111 that they were still within about 25 miles from the airport. |
| 0122:18 | The first officer informed the controller that they would stay at 10 000 feet, and the controller cleared SR 111 to maintain that altitude. |
| 0122:21 | The speed brakes were retracted as the aircraft descended through 12 550 feet. The rate of descent reduced to 1 000 fpm, then subsequently increased to 2 000 fpm until the aircraft levelled off between 10 150 and 10 300 feet. |
| 0122:33 | The first officer asked the captain whether he was in the emergency checklist for air conditioning smoke. The captain indicated that he was. |
| 0122:37 | The FDR recorded that the selected indicated airspeed had been changed from 320 to 249 KIAS. This is consistent with the applicable regulatory requirements, which stipulates that airspeed be reduced to a maximum of 250 KIAS when aircraft are at 10 000 feet or below. |
| 0122:48 | The captain provided some FMS advice as the first officer was inserting Halifax airport into the FMS to be able to display airport information, such as runway length and instrument approach information. |
| 0123:00 | As the airspeed was decreasing through 306 KIAS, the first officer asked the captain for his agreement to reduce the speed only slightly. The captain indicated that he was proceeding with the checklist, and that the first officer could fly the aircraft as he thought best. |
| 0123:22 | The airspeed stabilized at 300 KIAS, never reaching the previously selected 250 knots. |
| 0123:30 | The controller instructed SR 111 to turn to 180 and advised that they would be off the coast in about 15 miles. |
| 0123:37 | The first officer confirmed they were maintaining 10 000 feet. |
| 0123:45 | The captain referred to the CABIN BUS switch and asked for confirmation, which the first officer provided. |
| 0123:53 | The controller informed SR 111 that the aircraft would remain within 35 to 40 miles of the airport in case they had to land quickly. |
| 0124:01 | The first officer indicated that this was fine, and asked the controller to inform them when fuel dumping could start. |
| 0124:09 | The FDR recorded a disconnect of Autopilot 2 and an aural warning tone was heard on the CVR until the CVR ceased to record. |
| 0124:18 | The captain noted, and the first officer confirmed, that the autopilot had disconnected. |
| 0124:25 | The first officer informed Moncton ACC that they had to fly manually and asked for a protected block of altitudes between 11 000 and 9 000 feet. |
| 0124:35 to 0125:27 |
A land line conversation took place between Moncton ACC and the Halifax FSS, during which Moncton ACC advised Halifax FSS of the anticipated fuel dumping. |
| 0124:36 | The controller assigned an altitude block between 5 000 and 12 000 feet. |
| 0124:38 | The CVR recorded an altitude alert tone at 0124:38.4 and again at 0124:41.6. |
| 0124:42 | The captain called Moncton ACC and declared an emergency. The first officer, in an overlapping radio transmission, acknowledged that SR 111 was cleared between 12 000 and 5 000 feet, and advised that they were declaring an emergency at time zero-one-two-four (0124). |
| 0124:46 | The cabin crew indicated that they had lost electrical power in the cabin and that they were using flashlights to continue to prepare the cabin for landing. |
| 0124:52 | The controller acknowledged the 0124:42 SR 111 transmission. |
| 0124:53 | The captain called Moncton ACC and indicated that they were starting to dump fuel and had to land immediately. |
| 0124:54 | The FDR recorded the failure of lower yaw damper A. |
| 0124:57 | The controller replied that he would contact them in just a couple of miles. |
| 0124:57 | Channel A of FCC-1 lost primary power, and within 15 seconds (at 0125:12), all of the data being reported to the FDR by FCC-1 stopped. |
| 0125:01 | The first officer replied "Roger." |
| 0125:02 | The first officer restated that they were declaring an emergency. |
| 0125:05 | The controller acknowledged the emergency declaration. |
| 0125:06 | The pressure altitude, computed airspeed, and total air temperature parameters, as recorded in the FDR, became static. |
| 0125:06 | The aircraft's transponder Mode C, which provides aircraft altitude information to ATC radar, stopped transmitting. |
| 0125:06 to 0125:14 |
An ATC transmission of less than one second was received through VHF 1 and recorded on the CVR. The power for the captain's pitot heat was lost. The slats proximity sensor electronic unit B sensors changed from "target near" to "target far." The data from DEU-1 was lost; a switchover to DEU-3 occurred after 0125:14. |
| 0125:08 | The last message from ACARS was recorded when a tracker message for flight following was sent and acknowledged by the system. |
| 0125:16 | The first officer advised the captain that he was just flying, and not doing anything else. |
| 0125:16 | Moncton ACC transmitted a clearance to SR 111 to dump fuel on its present track, and to advise when the dump was complete. This transmission was not recorded on the SR 111 CVR. |
| 0125:20 | The captain referred to something that was burning already, and the first officer made a reference to landing. |
| 0125:33 | The first officer indicated that his side was all dark, and also made reference to standby instruments and speed. |
| 0125:34 | The FDR recorded the failure of upper yaw damper A. |
| 0125:40 | A second clearance from Moncton ACC to dump fuel was transmitted. |
| 0125:41 | Both flight recorders and the VHF radios (communications with ATS) stopped functioning. |
| 0125:46 | Moncton ACC recorded an unintelligible fragment of audio that could have been from SR 111. |
| 0125:50 | Transponder Mode C data was regained by ATC until 0126:04.1. |
| 0126:01 | The ACARS MU failed as a result of the fire event. |
| About 0130 |
The FADEC indicated that the engine [Engine 2] was shut down by use of the fuel switch at about 1 800 feet (±470 feet). |
| 0131:18 | The aircraft struck the water. |