An Airbus Canada aircraft (ABK386) reported a strong 15-second emergency locator transmitter (ELT) signal at FL350. The Joint Rescue Coordination Centre (JRCC) Trenton was advised. No impact on operations.
UPDATE: Supplemental information for the Airbus/Bombardier flight test crew reporting the signal: Aircraft being flown by the crew was an Air Baltic Airbus A220-300 (C-FOVG/ABK386).

At FL350, an Air Canada Boeing 777-300 (ACA848) from Toronto/Lester B. Pearson Intl, ON (CYYZ) to London/Heathrow, United Kingdom (EGLL) reported an intermittent emergency locator transmitter (ELT) signal between 0119Z and 0129Z. Joint Rescue Coordination Centre (JRCC) Trenton advised. No impact to operations.

TSB Report #A20F0039: C-FYJD, a B737-800 aircraft operated by Sunwing, was conducting flight SWG677 from Varadero Juan Gualberto Gomez (MUVR), Cuba to Vancouver Intl (CYVR), BC. During cruise, severe turbulence was encountered in vicinity of Helena Regional (KHLN), MT while on descent from FL380 down to FL350. During the encounter there was a temporary loss of control of the aircraft which was subsequently regained. The seat belt sight was on and a PA was made to passengers to be seated. A passenger that was in the aft lavatory during the event and sustained minor injuries. The flight continued to destination without further incident.

TSB Report #A20A0011: C-FDSN, an Airbus A320 operated by Air Canada was conducting flight ACA680 from Toronto Lester B Pearson International Airport, ON (CYYZ) to St John’s International Airport, NL (CYYT). While in cruise at FL350, the number 2 engine rolled back to approximately 54% N1, while the number 1 engine remained at 92% N1. The crew descended to FL290 with auto thrust commanded to 85% and both engines responded. The flight continued to destination without further incident. Maintenance is investigating.

An American, corporately registered Learjet 36A (N81GJ) from St. Johns, NL (CYYT) to Hamburg, Germany (EDDH) descended without clearance from FL350 to FL290 and proceeded direct CYYT due to a medical emergency.

A United Parcel Service Co. McDonnell Douglas MD 11F (N286UP/UPS203) from Louisville, KY (KSDF) to Cologne/Bonn, Germany (EDDK), at FL330, received their ocean clearance via data link at FL350 and climbed without a climb clearance. There was no traffic, safety was not jeopardized, separation was assured, the operation was not affected.

At time 2202Z and just west of 50N050W, a British Airways Boeing 787-9 (GZBKD/BAW293) on a flight from Heathrow/London Intl, UK (EGLL) to Washington/Dulles, VA (KIAD) declared a PAN PAN due to a pressurization issue and requested descent from FL410 to FL350. The flight was recleared to FL340. BAW293 reported the situation good at FL340 and PAN PAN cancelled at 2215Z. Flight continued to its destination and exited the Gander Intl, NL (CYQX) flight information region (FIR) at 2248Z.
UPDATE TSB Report #A20A0006: G-ZBKD, an Boeing 787-900 operated by British Airways, was conducting flight BAW293 from London Heathrow Intl. (EGLL), UK to Washington Dulles Intl. (KIAD), VA. The aircraft dispatched with the right air conditioning pack inoperative in accordance with the MEL. During the cruise portion while at FL410, the left air conditioning pack failed, resulting in a PACK ALTITUDE LIMIT warning. The checklist required a descent to FL340. At 195 nm NE of St John’s International Airport, NL (CYYT), the crew requested FL340, however it was denied by ATC. The crew then declared a PAN-PAN due to the pressurization issue and a descent to FL340 was made. Once the aircraft reached FL340, the crew reported the situation was normal and cancelled the PAN-PAN and continued to destination without incident.

A LOT Polish Airlines Airbus A340-300 (OOABD/LOT46) on a flight from Toronto/Lester B. Pearson Intl, ON (CYYZ) to Warsaw, Poland (EPWA) experienced moderate turbulence, deviated off course and descended from FL370 to FL350. Air traffic control (ATC) re-cleared the aircraft. No impact on operations.

At 0207Z, a Boeing 777 aircraft from Chicago/OHare, IL (KORD) to Zurich, Switzerland (LSZH) reported severe turbulence (Svr turb) over CEFOU intersection at FL350.

At 0010Z, a British Airways Boeing 747-400 (GCIVI/BAW20R) from Chicago/OHare, IL (KORD) to London/Heathrow, United Kingdom (EGLL) picked up the signal of an emergency locator transmitter (ELT) from FL350, 270/025NM from the La Tuque, QC (YLQ) non-directional beacon (NDB), up to 090/20NM from the YLQ NDB, at 0015Z. Joint Rescue Coordination Centre (JRCC) Trenton was notified.

An Emergency Locator Transmitter (ELT) signal was reported at 0224Z for 3 minutes. The signal strength was strong, and was heard 40NM South of Mont-Joli, QC (CYYY) at FL350. The Joint Rescue Coordination Centre (JRCC) Trenton notified. No impact to operations.

An Air Canada Airbus A320-211 (C-FTJQ/ACA948) from Montreal/Trudeau, QC (CYUL) to Pointe-à-Pitre, Guadeloupe (TFFR) asked the Boston centre if it could return to CYUL due to a mechanical problem. Once it was 20 NM from CYUL, ACA948 declared an emergency. The aircraft landed without incident at 1641Z.
AOR-247060-V1 Update: While inbound south of CYUL, an Air Canada Airbus A320-211 (C-FTJQ/ACA948) from Montreal/Trudeau, QC (CYUL) to Pointe-à-Pitre, Guadeloupe (TFFR) declared an emergency. There was a controls problem. The aircraft landed, then came to a stop on the runway, where emergency vehicles were present. The aircraft then cleared the runway on its own at 1653Z. Impact on operations: ACA809 was delayed by 10 minutes.
Update TSB Report #A19Q0037: C-FTJQ, an Airbus 320-200 operated by Air Canada as flight AC948 with 6 crewmembers and 89 passengers on board was en route from Montreal/Pierre Elliott Trudeau Intl (CYUL), QUE, to Le Raizet - Pointe-à-Pitre, Guadeloupe, France (TFFR). During cruise at FL350 near Bermuda, the flight crew received an ECAM message with the FLT CONTROL page showing the left spoilers in the UP position. After discussion with the company, the decision was made to return to CYUL. When the aircraft was about 20 nm south of CYUL, the crew declared a PAN PAN and carried out an uneventful landing on Runway 24L at 16 h 43Z with ARFF on standby. Spoiler 1R actuator was replaced in accordance with the Aircraft Maintenance Manual and the aircraft was returned to service following a successful operational test.

A British Airways Boeing 777-200 (BAW5CA) from Toronto/Pearson International, ON (CYYZ) to London/Heathrow, UK (EGLL) reported severe turbulence at FL370, and descended to FL350. No impact to operations.

A Philippine Airlines Boeing 777-300 (RPC7782/PAL116) from Manila, Philippines (RPLL) to Vancouver, BC (CYVR) was at FL350 and started descending without clearance. Controller noticed and then cleared the aircraft to FL290. No impact to operations.

An Air Canada Boeing 787-9 (C-FVLU/ACA858) on a flight from Toronto/Lester B. Pearson Intl, ON (CYYZ) to London/Heathrow Intl, UK (EGLL) was cleared to FL370 and was observed descending from FL350 to FL340 and speed decreasing by 80 knots. ACA858 re-initiated a climb to FL370. No impact to operations.

A Delta Air Lines Boeing 767-300 (DAL96) on a flight from Detroit Metro/Wayne County, MI (KDTW) to Paris/Charles de Gaulle, France (LFPG) cleared to climb to FL350 reported a traffic alert and collision avoidance system (TCAS) resolution advisory (RA). Traffic had been passed as a Delta Air Lines Boeing 757-200 (DAL737) on a flight from Boston Intl, MA (KBOS) to Los Angeles Intl, CA (KLAX) in opposite direction at FL360.

A Delta Airlines Boeing 737-900 (DAL2713) from Portland, OR (KPDX) to John F. Kennedy, NY (KFJK) East Bound at FL350 reported an emergency locator transmitter (ELT) signal passing over London, ON (CYXU). Other aircraft reported the ELT in the vicinity of CYXU. Joint Rescue Coordination Centre (JRCC) Trenton notified. No further reports received.

A Sunwing Airlines Boeing 737-800 (SWG508) from Cancun, Mexico (MMUN) to Toronto/Lester B. Pearson, ON (CYYZ) that was inbound declared an emergency due to partial hydraulic failure. Emergency equipment requested. Aircraft landed safely and taxied to the apron without further incident.
Update TSB #A19O0031: C-FLSW, a Boeing 737-800 aircraft operated by Sunwing Airlines, was conducting flight SWG508 from Cancun Intl (MMUN), Mexico to Edmonton Intl (CYEG), AB with 6 crew members and 177 passengers on board. During the climb to cruising altitude after the departure from MMUN, the flight crew received a HYDRAULIC SYS B ENG2 LOW PRESSURE indication. Subsequently, when the aircraft reached its cruising altitude of FL350, the corresponding fluid quantity began to drop. The flight crew contacted the operator’s Operational Control Centre (OCC) after following the QRH procedure, and the decision to divert to CYYZ was made. Upon being handed over to Toronto Centre (CZYZ) during the descent to CYYZ, the flight crew declared a PAN PAN. The aircraft proceeded to land uneventfully with ARFF standing by. After the landing, ATC requested that the aircraft hold its position on Taxiway H, whereupon ARFF reported continuous fluid leakage from the number 2 engine. The number 2 engine was shut down, and the aircraft taxied to the infield terminal on one engine. The operator’s maintenance replaced the number 2 Engine Driven Pump (EDP) and, after an operational check, the aircraft was returned to service.

TSB Report #A19F0316: C-GKVV, a Boeing 737-800 operated by Sunwing Airlines Inc., was conducting flight SWG640 from Toronto/Lester B. Pearson Intl. (CYYZ), ON to Holguin/Frank País Intl. (MUHG), Cuba. During the climb to FL340, a TCAS RA "level off" was received at FL335 due to crossing traffic at FL350. The RA was followed. The flight crew was advised of the traffic by ATC. The flight continued to destination without further incident.

TSB Report #A19F0310: C-FYJE, an Air Canada Airbus 319-100 operated by Air Canada Rouge, was conducting flight ROU1735 from Lima/Jorge Chávez Intl. (SPJC), Peru to Toronto/Lester B. Pearson Intl. (CYYZ), ON. During cruise at FL350, 45nm W of Jacksonville Intl. (KJAX) FL, the flight encountered turbulence and the flight crew noted the Left Hand (LH) engine N1 decreased. The flight crew requested a lower altitude in search of smoother air. The flight leveled of at FL310 and the LH engine resumed normal operation for the remainder of the flight. Maintenance inspected the engine and found the LH engine HMU (hydro mechanical unit) faulty. Replacement of the HMU took place and the aircraft was returned to service.

TSB Report #A19F0274: C-FMWV, a Boeing 767-333ER operated by Air Canada Rouge, was conducting flight ROU1852 from Las Vegas/McCarran Intl. (KLAS) NV to Toronto/Lester B. Pearson Intl. (CYYZ), ON. Upon reaching cruise altitude of FL350, the flight crew noted smoke and odor in the cockpit. Applicable QRH drills were completed and flight crew declared a MAYDAY. The flight subsequently landed in KLAS RWY 26L with ARFF on standby. After landing, the flight crew reported that the LH Brake was over 600 degrees Celsius. The aircraft taxied to a remote location on the airport to allow the brakes to cool. Once the brakes reached an acceptable temperature the aircraft taxied to the gate uneventfully.

TSB Report #A19F0040: C-GEOU, a Boeing 767-300 aircraft operated by Air Canada rouge, was conducting flight ROU1852 from Las Vegas/McCarran Intl (KLAS), NV to Toronto/Lester B. Pearson Intl (CYYZ), ON with 8 crew members and 282 passengers on board. During cruise flight at FL350 approximately 90 nm NNW of Amarillo/Rick Husband Intl (KAMA), TX, the cabin crew reported smoke coming out of a coffee maker in the forward galley. A cabin crew member discharged a fire extinguisher in the affected area, and notified the flight crew. The QRH was executed, and after evaluating the situation, the decision to continue to destination was taken. The aircraft landed at CYYZ without further incident. An entry was made in the log book, and the event was captured in the air operator’s Safety Management System (SMS).

A Kuwait Airways Boeing 777-333ER (9KAOH/KAC117) from Kuwait City, Kuwait (OKBK) to New York, NY (KJFK) requested and was issued clearance to FL350, climbed to FL360, and descended back to FL350. No traffic. No impact on operations.

TSB Report #A19F0021: C-GTQX, a Boeing 737-800 aircraft operated by Air Transat, was conducting flight TSC703 from Roatán/Juan Manuel Gálvez Intl (MHRO), Honduras to Toronto/Lester B. Pearson Intl (CYYZ), ON with 6 crew members and 161 passengers on board. During cruise flight at FL350, approximately 50 nm south southeast of Pittsburgh Intl (KPIT), PA, the aircraft experienced a pressurization problem, which prompted the flight crew to don their oxygen masks. An emergency was declared, and the flight crew executed a rapid descent to 10 000 feet. Once at 10 000 feet, the flight crew regained control of the pressurization, and cancelled the emergency. The flight continued to destination and landed at CYYZ without further incident. There were no injuries. The operators maintenance is troubleshooting the problem.

A CargoJet Airways Boeing 757-200 (CJT919) on a flight from Calgary Intl, AB (CYYC) to Cincinnati/Northern Kentucky, KY (KCVG) departed CYYC, got to flight planned altitude of FL350, and shortly thereafter declared an emergency with a pressurization issue. The aircraft then requested a descent and a descent to 10,000 ft was given. The aircraft descended to FL230, and requested clearance back to CYYC at 15,000 ft. Clearance to CYYC was issued over the arrival gate at 16,000 ft as the aircraft felt an emergency situation was no longer required. Air Traffic Control (ATC) gave the aircraft priority and brought the aircraft in direct. Aircraft landed safely, no impact to operations.
Update TSB Report #A19W0134: C-GCJT, a Boeing 757-200 operated by Cargojet Airways, was conducting flight CJT919 from Calgary Intl (CYYC), AB to Covington/Cincinnati/Northern Kentucky Intl (KCVG), KY. Upon reaching cruising altitude, the cabin altitude climbed at 100 per minute and the “cabin altitude” warning sounded. The flight crew declared an emergency, initiated a controlled descent, and donned oxygen masks. The aircraft returned to CYYC and landed without further incident. There were no injuries. At the time of the occurrence, the Equipment Cooling Overboard Exhaust valve was deferred by company maintenance and locked in the SMOKE (partially OPEN) position as per the MEL requirements. Upon return to CYYC, company maintenance found the value in the fully open position. The equipment overboard cooling exhaust valve failed to the full open position while in the locked out position, which created the loss of cabin pressure. The valve was replaced and tested. The aircraft was returned to service.

A WestJet Boeing 737-700 (WJA702) from Vancouver, BC (CYVR) to Toronto/Pearson, ON (CYYZ) reported a strong emergency locator transmitter (ELT) signal for approximately 1 minute at FL350, eastbound, in the vicinity of Winnipeg. The joint rescue coordination centre (JRCC) Trenton was advised.

A WestJet Boeing 737-800 (WJA1416) from Calgary Intl, AB (CYYC) to Orlando Intl, FL (KMCO) switched to Salt Lake City (SLC) for further instructions to climb to FL350. The switching of instructions were meant for a WestJet Boeing 737-700 (WJA1460) from Calgary Intl, AB (CYYC) to Las Vegas Intl, NV (KLAS). The read back error was not identified and WJA1416 initiated a climb from FL330 to FL350 unexpectedly. No other impact on operations.

An Air Algerie Airbus A330 (DAH2703) reported severe turbulence at FL370. The aircraft descended to FL350 and reported a smooth ride. The Halifax (HZ) Flight Information Centre (FIC) was advised. No impact to operations.

A Southeast Airmotive Corporation aircraft (flight SPUR81), an Ethiopian Airlines aircraft (flight ETH503), and an Air France aircraft (flight AFR650) reported severe turbulence at FL290, FL330-FL350 and FL360 in an area bounded by Halifax, NS VOR/DME (YHZ), Grindstone (Îles-de-la-Madeleine), QC VOR/DME (YGR) and Sydney, NS VOR/DME (YQY). SIGMET G1 issued after Halifax (HZ) Flight Service Station (FSS) was advised of each of the reports. Aircraft continued on route as filed.

An Air France aircraft (AFR431) reported severe turbulence at FL350. The aircraft descended to FL330. No impact to operations.

Aircraft reported severe turbulence at 4415N05739W and FL350. No altitude change.

A Swiss International Air Lines Airbus A330-300 (SWR17P) from New York/John F. Kennedy, NY (KJFK) to Zurich, Switzerland (LSZH) reported severe turbulence at FL350, however, did not change altitude.

A Cargologicair Ltd. Boeing 747-400 (GCLAA/CLU856) from Chicago/OHare, IL (KORD) to Frankfurt, Germany (EDDF) encountered severe turbulence at FL350. There was no altitude change and there were no reported injuries or damage. Halifax Flight Information Centre (FIC) was notified.

A KLM Royal Dutch Airlines Boeing 777-300 (KLM168) from Atlanta/Hartsfield-Jackson, GA (KATL) to Amsterdam, Netherlands (EHAM) reported severe turbulence at FL350. Aircraft did not change levels and there were no reported injuries or damage. Halifax (YHZ) Flight Information Centre (FIC) was notified.

Severe turbulence reported at FL370 by a Qatar Airways Airbus A350-900 (QTR728) on a flight from Philadelphia Intl, PA (KPHL) to Doha, Qatar (OTHH). The aircraft descended to FL350. Flight information centre (FIC) advised.

A Delta Air Lines Boeing 767-300 (N189DN/DAL474) on a flight from New York/John F. Kennedy, NY (KJFK) to Venice/Marco Polo, Italy (LIPZ) had smoke and fumes in cockpit. Flight deviated 5NM left of course and descended to FL275 from FL350 and turned back to St. Johns Intl, NL (CYYT).
Update TSB Report #A19A0078: N189DN, a Boeing 767-332 aircraft operated by Delta Air Lines, was conducting flight DAL474 from New York/Kennedy Intl (KJFK), NY to Venice/Marco Polo Intl (LIPZ), Italy. While in cruise flight at about 230 nm SE of St. Johns Intl. (CYYT), NL (45°27 N, 048°10 W), the cabin crew detected an electrical odour in the cabin, although no visible smoke was noted. The flight crew was notified, and the captain transferred aircraft control and commenced the smoke and fumes quick reference handbook procedure. The flight crew then received an EICAS message regarding the left recirculating fan, and secured the fan. The flight crew conferred with their company maintenance control, decided to divert to CYYT, and coordinated with air traffic services for the diversion. The crew declared an emergency and landed at CYYT without further incident. Emergency services at CYYT determined no fire was present. Maintenance personnel subsequently inspected the aircraft and verified that the left recirculation fan was the source of the odour.

A Saudi Arabian Airlines Boeing 777-300 (SVA020) on a flight from New York/John F. Kennedy Intl, NY (KJFK) to Jeddah, Saudi Arabia (OEJN) reported moderate to severe turbulence at FL350. The aircraft descended to FL330 and reported continuous moderate turbulence but remained at that level. Halifax (HZ) flight information centre (FIC) advised, no impact on the operation.

A Delta Air Lines Boeing 757 200 (N822DX/DAL260) from Minneapolis, MN (KMSP) to Keflavik, Iceland (BIKF) started climbing from FL350 to FL370 without clearance. The aircraft stopped climbing at FL358 and immediately went back down to FL350. No impact on operations.

An American, corporately registered Boeing 737-300 (N604SW) from Portland Intl Jetport, ME (KPWM) to Keflavik, Iceland (BIKF) was cleared from FL370 to FL350 due to traffic. After initially levelling off at FL350, the aircraft descended from FL350 without clearance, and contacted air traffic control (ATC) to indicate that they were descending to their expected oceanic flight level. Aircraft was re-cleared to FL290. No traffic. No impact to operations.

An Air Canada Rouge Airbus A321-211 (ROU1536) from Toronto/Lester B. Pearson, ON (CYYZ) to St. Johns, NL (CYYT) reported pressurization problem. Diverted to Halifax/Stanfield, NS (CYHZ). No emergency reported. Landed no issue. No impact on operations.
Update TSB #A19A0056: C-FJQD, an Airbus A321-211 aircraft operated by Air Canada rouge LP was conducting flight ROU1536 from Toronto Lester B. Pearson Intl (CYYZ), ON to St. John’s Intl (CYYT), NL. During cruise at FL350, 35 nm NW of Halifax Stanfield Intl (CYHZ), NS the flight crew received a fault message of an aircraft air conditioning PAC fault 1 and 2. One of the PACs was already deferred as per the MEL and the subsequent fault caused a loss of pressurization. The crew conducted the required checklists, declared a PAN PAN, and requested a descent and a diversion into CYHZ where it landed without incident.

An Air France Boeing 777 300 series (AFR639) from Houston, TX (KIAH) to Paris, France (LFPG) reported severe turbulence and climbed from FL350 to FL360.

A WestJet Boeing 767-338 (C-GOGN/WJA4) from Gatwick, England (EGKK) to Toronto/Lester B. Pearson, ON (CYYZ) was at FL330. The aircraft requested FL350, and was given a clearance (CLX) by air traffic control (ATC) for FL340 and issued requested level not available. Shortly after, WJA4 was observed at FL347 before the aircraft returned back down to cleared level of FL340. There was traffic at FL350, 6 minutes behind.

Multiple flights reported an emergency locator transmitter (ELT) signal at FL350 and FL370.

An Air France Airbus A380-800 (FHPJI/AFR006) from Paris/Charles de Gaulle, France (LFPG) to New York/John F. Kennedy, NY (KJFK) climbed from FL350 to FL362, due to turbulence from an Aer Lingus Ltd. Boeing 757-200 (EILBR/EIN11J) from Dublin, Ireland (EIDW) to Philadelphia, PA (KPHL), without clearance.

Estimate passed to the Moncton (QM) controller for JEBBY from New York (NY) on a Thomas Cook Airlines Ltd. Airbus A330-243 (GMLJL/TCX2619) from Frank Pais, Cuba (MUHG) to Manchester, UK (EGCC). The NY controller passed FL370 and the QM JEBBY controller read back FL350. The aircraft checked in level at FL370. No other traffic in the area. Shift manager and NY advised. No operational impact.

At 1449Z, a Cargolux Airlines Boeing 747-800 (LXVCM/CLX45A) from Covington/Cincinnati International, KY (KCVG) to London/Heathrow, UK (EGLL) executed contingency procedures and descended from FL370 to FL350 without clearance due to severe turbulence. CLX45A was re-cleared and continued at FL350.

An Air France Boeing 777 200 (AFR689) from Atlanta Intl Airport, GA (KATL) to Charles de Gaulle Airport, France (LFPG) reported severe turbulence at FL350 and climbed to FL370. No impact to operations.

An Air Canada Embraer ERJ 190-100 IGW (ACA690) from Toronto/Lester B. Pearson Intl, ON (CYYZ) to St. Johns Intl, NL (CYYT) reported hearing a loud and clear emergency locator transmitter (ELT) signal for 2 minutes at FL350. No impact on operations.

An Icelandair EHF Boeing 757-200 (TFISJ/ICE688) from Orlando, FL (KMCO) to Keflavík, Iceland (BIKF) declared MAYDAY and requested to land at the nearest aerodrome. Air traffic services (ATS) cleared the aircraft to divert to the Canadian Forces Base in Bagotville, QC (CYBG) and descend. At 0201Z, ICE688 indicated that it had a cracked windshield but that the situation was under control. ICE688 landed on Runway 11 at CYBG at 0215Z. Emergency services were deployed. No other impact on operations.
Update: TSB Report #A18Q0172: TF-ISJ, an Icelandair Boeing 757-200 (ICE688) with 7 crew members and 155 passengers on board, was on an IFR flight from Orlando Intl (Florida) to Keflavik (Iceland). While the aircraft was approximately 50 miles southeast of the Bagotville, Quebec (CYBG) airport, at FL350, the pilot-in-command noticed the presence of arcing in the right-hand corner of the left forward window (LFWD WINDOW). The windshield heat was turned off and shortly afterwards, a loud cracking sound was heard. The flight crew members put on their oxygen masks and declared MAYDAY due to the crack in the front-left windshield and conducted an emergency descent. When it passed FL250 and noticed that the cabin pressure had remained constant, the emergency descent was rejected. The pilot-in-command took the oxygen mask off, but the first officer kept it on as a precaution. A normal descent was followed and the flight crew requested to be diverted to CYBG, where the aircraft landed without any problems.
UPDATE Aviation Incident Report #15745: An Icelandair Boeing 757-200 (TFISJ/ICE688) departed Orlando, FL (KMCO) Runway 36R at 2312Z and the flight was uneventful for almost 3 hours. During cruise and inbound to SAVERY FL350 around 0150Z, when the crew was working on getting an oceanic clearance from Gander, the captain noticed bright sparks coming from lower right corner of the left forward (LFWD) window. The sparks increased very rapidly and spread from right to left. The captain notified the first office (FO) and turned the window heat for that window off. The crew started working on the QRH and heard a loud bang and cracking noise. The crew decided to declare an emergency on the Montreal frequency and asked for a lower altitude. The flight was cleared at lower altitude, and the crew in the cockpit donned the oxygen masks, established crew communication and started the descent. When the crew noticed that the cabin pressure was not rising and was not uncontrollable, the captain decided to abort the emergency descent procedure but did continue the descent with the masks on as a precautionary measure. Captain gave the crew the alert call. Passing FL250 and because the cabin pressure was still normal, the captain took off his/her oxygen mask to get a clearer picture of the situation, but asked the FO to keep their mask on as a precaution. Montreal air traffic control (ATC) was very helpful and gave the crew a direct to Bagotville, QC (CYBG).

After giving out clearance to descend to FL350, air traffic control (ATC) did not receive a clearance read-back. An Air Transat Boeing 737-800 (TSC774) from Vancouver Intl, BC (CYVR) to Montreal/Pierre Elliott Trudeau, QC (CYUL) was seen in descent at FL347. When questioned, the aircraft mentioned that he was descending to FL340. No impact on operations.