Cortez, CO, USA
C-FKOJ
AIRBUS A320
Air Canada flight 795 departed Lester B. Pearson International Airport, Toronto, Canada, at approximately 2010 eastern standard time on a non-stop flight to Los Angeles International Airport, Los Angeles, California. At 2115 Mountain Standard Time, the flight crew checked in with Denver Center while at FL360. Aircraft radios were configured COMM1 on ATC frequency (ZDV) and COMM2 on 121.5 MHZ. At 2134 ZDV radar sector 37 directed the crew to contact ZDV on frequency 132.87; however, they did not respond. The flight was without radio contact (NORDO) for 37 minutes in ZDV and Los Angeles Center airspace. Communications were reestablished with the ZDV R24 controller via air to air relay with N613WF, at FL490. ACA flight 795 was then directed to contact Los Angeles ARTCC on frequency 127.35. According to the Federal Aviation Administration's preliminary pilot deviation report, after landing the pilot of the incident flight called the ZDV Operations Manager-in-Charge and explained that they were receiving static on emergency frequency 121.5 and had turned the volume down. The pilot also stated that they had received Aircraft Communications Addressing and Reporting System (ACARS) messages after they had contacted ZLA.
ACA795 departed Lester B. Pearson International Airport (CYYZ), Toronto, Canada at approximately 2010 eastern standard time, November 5, 2009 (0010 UTC on November 6, 2009) on a non-stop flight to Los Angeles International Airport (KLAX), Los Angeles, California. At 2115 MST, ACA795 checked in with ZDV at FL360. Aircraft radios were configured COMM1 on ATC frequency (ZDV), COMM2 on 121.5 MHZ. At 2134 ZDV radar sector 37 directed ACA795 to contact ZDV on frequency 132.87. ACA795 did not respond. ACA795 was NORDO for 37 minutes in ZDV and ZLA airspace. The following timeline captures information provided by ZDV and the Canadian Transportation Safety Board regarding the chronological events pertaining to ACA795: ACA795 Timeline Time listed is MST on November 5, 2009 ACA795 – Air Canada Flight 795 ZDV- Denver Air Route Traffic Control Center ZLA – Los Angeles Air Route Traffic Control Center Dispatch – Air Canada Dispatch Originator/ Time Action/Event ATC Sector MST ACA795 2055 Automated Aircraft Communications Addressing and Reporting System (ACARS) transmission from ACA795 to Air Canada Maintenance via a Nebraska ARINC ground station. This was the last communication between ACARS and ACA795 before the NORDO 37R 2115 ACA795 checks in with ZDV at FL360 on frequency 125.67 37R 2134 ZDV directs ACA795 to contact ZDV (sector 24R) on frequency 132.87 24R 2135 ZDV attempts two radio checks with ACA795 – no response 25R 2135 ZDV directs ACA795 to contact ZDV on frequency 132.87 - no response 37R 2135 ZDV inter-facility coordination – 37R/37R requests 30RA attempt to have ACA795 contact ZDV on frequency 125.67 37R 2135 ZDV directs ACA795 to contact ZDV – no response 37R 2135 ZDV attempts radio check with ACA795 – no response 25R 2136 ZDV attempts radio check with ACA795 – no response 25R 2136 ZDV requests Frontier flight (FFT) 860 attempt to contact ACA795 via air to air communications – negative result 30R 2136 ZDV makes multiple attempts to contact ACA795 on frequency 125.67 – no response ZDV 2137 ZDV request Air Canada dispatch send a message to ACA795 via ACARS Air Canada sends the message. The message was transmitted via a New Mexico ground station. The airborne ACARS set on ACA795 was on a frequency that was not available at the New Mexico ground station. Accordingly, the New Mexico ground station fails to establish an uplink with ACA795. The air dispatch system records the “no uplink” status but does not report “no uplink” to Air Canada dispatch for 30 minutes. The 30 minute system configuration at Air Canada has since been changed to 8 minutes. 30RA 2137 ZDV inter-facility coordination – 30RA advises 37R unable to establish communications with ACA795 on frequency 125.67 24R 2137 ZDV requests Frontier flight (FFT) 778 to contact ACA795 via air to air communications on frequency 121.5 guard 25R 2138 ZDV requests FFT860 attempt to contact ACA795 via air to air communications on frequency 121.5 guard 37R 2138 ZDV attempts radio check with ACA795 – no response 25R 2139 FFT860 reports unable to contact ACA795 on frequency 121.5 guard 24R 2140 FFT788 reports unable to contact ACA795 on frequency 121.5 guard 24R 2141 ZDV requests FFT780 attempt to contact ACA795 via air to air communications on frequency 135.4 37R 2141 ZDV attempts radio check with ACA795 – no response 24R 2142 FFT780 reports unable to contact ACA795 on frequency 135.4 24R 2143 ZDV attempts radio check with ACA795 – no response 25R 2143 ZDV requests Frontier flight (FFT) 266 attempt to contact ACA795 via air to air communication on frequency 127.07 ZDV 2144 ZDV advised the domestic events network (DEN) that ACA795 is NORDO 24R 2144 ZDV requests ACA795 IDENT if receiving transmission – no IDENT observed 25R 2145 FFT266 reports unable to contact ACA795 on frequency 127.07 24R 2150 ZDV advised ZLA that ACA795, inbound to Los Angeles, has been NORDO for 15 minutes Dispatch 2150 Air Canada dispatch sends a second ACARS message to ACA795 a total of five ACARS messages are sent to ACA795. Air Canada dispatch also attempted to contact ACA795 via selective-calling radio system (SELCAL). ACA795 did not have HF SELCAL and the VHF SELCAL notification did not have an audio feature. 24R 2151 ZDV attempts radio check with ACA795 – no response 37R 2151 ZDV attempts radio check with ACA795 – no response 24R 2152 ZDV directs ACA795 to contact ZLA on frequency 127.35 – no response 25R 2153 ZDV requests FFT266 attempt to contact ACA795 on frequency 133.325 25R 2154 FFT266 reports unable to contact ACA795 on frequency 133.325 24R 2156 ZDV attempts radio check with ACA795 – no response ACA795 2157 ACA795 uses ACARS to obtain LAX weather and LAX automated terminal information service (ATIS)from the ARINC server located at San Francisco International Airport (SFO). This query did not re-establish the ACARS link between Air Canada dispatch and ACA795 24RA 2201 ZDV queries ZLA, sector 36R, to inquire if ACA795 had checked in on frequency 127.35 – negative response 24R 2202 ZDV attempts radio check with ACA795 – no response 25R 2205 ZDV requests Continental flight (COA) 752 attempt to contact ACA795 via air to air relay on frequency 133.325 Dispatch 2207 Air Canada dispatch receives notification from ARINC of “no uplink” failure for ACA795 25R 2211 ZDV requests COA752 attempt to contact ACA795 via air to air relay on frequency 127.07 37R 2211 ZDV requests N613WF transmit to ACA795 to contact ZLA on frequency 127.35 37R 2211 ACA795 receives N613WF transmission 37R 2212 N613WF reports that they had established communications with ACA795 25R 2212 COA752 makes multiple attempts to contact ACA795 on Frequency 127.02 37R 2212 N613WF advises ACA795 that ATC has been trying to reach them for 45 minutes 24RA 2214 ZLA advised ZDV that ACA795 reported that they were on frequency 125.67 during the NORDO period ACA795 2227 ACA795 begins descent into LAX triggering automatic ACARS Reporting to the Air Canada ACARS server. This re-establishes an ACARS link between ACA795 and Air Canada dispatch resulting in the release of the queued ACARS messages Communications with ACA795 were re-established by ZDV R24 via air to air relay with N613WF at FL490. ACA795 was directed to contact Los Angeles ARTCC on frequency 127.35. According to the FAA preliminary pilot deviation report, after landing, the pilot of ACA795 called the ZDV Operations Manager-in-Charge (OMIC) and explained that they were receiving static on frequency 121.5 and had turned the volume down. The pilot also stated that they had received ACARS messages after they had contacted ZLA. National flight data center (FDC) notice to airman (NOTAM) 4/4386, special notice, states in part that all aircraft operating in the United States National Airspace, if capable, shall maintain a listening watch on VHF guard 121.5 or 243.0.
The failure of the ACA795 flight crew to monitor and/or switch to the appropriate air traffic control frequency.
Source: NTSB Aviation Accident Database
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