C-FKOJ

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.