Mazatlan (MMFO) Oceanic Control Area

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invergordon

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I would like to hear from anyone who has received HF comms from QANTAS or Air New Zealand flights that fly between Auckland/Sydney to Dallas/Ft. Worth/Houston while they are in Mexican airspace. My understanding is there is airspace called Mazatland OCA (MMFO) between SFO (Oakland OCA) and the Mexican mainland.

I don't see a Mexican ground station mentioned in the MWARA listings so I was wondering who controls that airspace on an HF basis.

I do understand that transitions can occur via CPDLC but I have heard these aircraft call SFO on entry from the Mexican side but I don't know who is handing them off and if that entity has an HF capability.

Any help would be appreciated as I'd like to capture some comms on this.

Cheers,
Michael
 

brandon

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I've heard aircraft off Baja and the Pacific side of Mexico talking to San Francisco. A few times I have logged aircraft calling Mexico Radio but it's pretty rare to hear it. Further south they will talk to Cenamer, but that would probably not be the case for that QF flight.

Here is a recorded transmission of an American flight getting handoff from SF to Mazatlan on 5547.
solarix.net · Logs 17-Dec-2011
 

invergordon

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Thanks Brandon, that's interesting to know. Did you log the frequency when the aircraft called Mexico Radio? Was it 5547kHz each time? Maybe SFO takes guard for Mexico in that piece of airspace?
 

majoco

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One of the older Arinc charts shows a considerable overlap from our SP6 to the CEP2 MWARA areas. The CEP2 doesn't show on more recent charts but it goes right over to the Mexican coastline where I assume (careful!) that hi-level VHF comms takes over. The control for CEP2 appears to be SFO on Hawaii but that's quite a stretch, so it could come from the mainland too..
I don't know what the route is from AKL to Houston but it may well pass over PPT to the south even if it doesn't stop. I'll have to look at the schedules and guess at a time when they could be in the CEP2 area. There's a good VOR and high power NDB on Rangiroa in the north of the Marquesas even if the GPS/INS is working well!

PS - found a couple of interesting charts - the AirNZ bumph that they hand to the punters shows that the route AKL - IAH goes over Fiji and Hawaii - plot a real great circle path and it curves south to PPT then goes up to the equator north of the Marquesas then almost straight to IAH south of the Baja peninsula. AirNZ to DFW stops over at SFO.
 
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brandon

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Mexico Radio was on the 6649 and 10024 combo. Most of the traffic will be in Spanish.
 

AirScan

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Michael,

My understanding is there is airspace called Mazatland OCA (MMFO) between SFO (Oakland OCA) and the Mexican mainland. I don't see a Mexican ground station mentioned in the MWARA listings so I was wondering who controls that airspace on an HF basis.
I've also wondered about this airspace and those flights you mentioned. Attached is part of a current Aeronautical chart that shows Merida Oceanic CAR-A frequencies (2887, 5550, 6577, 8918, 11396, 13297, 17907) listed for this Mazatlan Oceanic airspace area.

However after many years of monitoring I have never heard "Merida Oceanic" transmitting on any of these CAR-A net frequencies ever. Actually I have never heard "Merida Oceanic" on any HF frequencies. Anyone know the status of this facility ?

As noted on the ARINC chart this area is also covered by the San Fransico CEP2 frequencies, although you don't hear them on these either. I strongly suspect these flights are handed off (via CPDLC) directly from the San Francisco SP (South Pacific) net frequencies to/from Mazatlan on VHF ?

What are the chances there is someone in Mexico on this forum that can monitor Mazatlan on 128.00 or 124.40 on VHF to confirm the handoff ?

AS
 

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invergordon

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Hi Airscan, thanks for that, it is a sort of 'unknown quantity' in terms of radio comms. I've heard ANZ29 a few times calling Tahiti after exiting SFO OCA and while they are CPDLC equipped, capable and using it the handoff from SFO still includes a procedure to contact the next OCA via HF radio and get a SELCAL check.

With the recent solar flare activity I can't hear much this evening on 5547 but I may keep a recorder going and see if QFA7 (Sydney-Dallas/Ft. Worth) turns up north of 20N and whether they get handed off on this frequency or not.
 

invergordon

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I have the good rub from ARINC on this when I specifically asked about the ANZ flights from Auckland to Houston:

"We use 3413/5574/8843/8915/13354 for eastbound flights up to 120W. We then hand them off to Mazatlán Oceanic on VHF."

I assume this would apply to the QFA7 flight as well.

My only comment on ARINC's response is that the Mazatlan OCA begins a long way out from the coast the further south one goes and a quick check of some of the flight plans would indicate that if SFO handed off the flight at the OCA boundary then VHF coverage is extended a long way from the Mexican coast. So I'm think that in these cases SFO retains control inside Mazatlan OCA until the aircraft is in VHF coverage. I might check the distances when I get a moment.

I did record 5574kHz last night but haven't had a chance to review and given a one in five chance of getting the frequency correct I'm not hopeful! Around 0930Z there was some traffic on 5574 but also QFA7 (the only eastbound of interest) was only halfway across the Pacific so by the time it was handed off it may have been daylight there and the frequencies in use would probably have changed up.
 

invergordon

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OK, my recording yielded some good info. At approximately 1445Z SFO is heard providing QFA7 frequencies of 6640 and 11342 as they transition the SFO OCA boundary into Mazatlan OCA.

So tonight I'll monitor 6640Hz and see what comes up. Recording is attached as a zip file for those interested.
 

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AirScan

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Thanks for that. Hard to make out the context of the transmission. 6640 and 11342 are LDOC frequences, so maybe nothing to do with ATC ? They archive both those frequencies over at LiveATC, might find something there on the tapes ?
 

invergordon

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The flight, time and location should make up the context. I used FR24 playback to locate QFA7 at around 1445Z and it was right on the boundary of SFO and Mazatlan OCA's but I suppose it's my eager assumption that this was a hand off to Mexican airspace.

On this site: https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/ifr/ is a planning map called PORC and on that it labels the Mazatlan OCA as "Uncontrolled Airspace". This would infer that Mexico doesn't positively control that space and one wonders that the reason for that would have been that hardly any commercial aircraft route in that airspace, maybe that will change in the future with more flights capable of reaching southern USA airports from Pacific nations. This could explain why SFO provide the flights with LDOC frequencies as a 'just in case' measure.

A subsequent note from ARINC advised:

"Beyond Mazatlán’s airspace should they need to contact us, we have the following available:

VHF 130.7 in Mexico
VHF 128.9 or 131.17 in Texas
HF LDOCF 3494/6640/11342/13348/17925/21964 depending on the time of day (both SFO/NYC)"

I just wonder how much control there is for these flights over Mexico?
 
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invergordon

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While listening to 5574kHz this evening I heard SFO talking to QANTAS 8 (Dallas/Ft. Worth-Sydney) on first contact. A check then on FlightAware showed that they were just crossing the Baja California coast into Mazatlan OCA airspace, see attachment. So it seems SFO take guard of these flights west bound but hand them off to LDOC HF frequencies east bound until in VHF range.

The circle is complete, thanks to everyone who had their input.
 

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AirScan

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While listening to 5574kHz this evening I heard SFO talking to QANTAS 8 (Dallas/Ft. Worth-Sydney) on first contact.
Thanks for that. So they do use the CEP frequencies initially westbound. Any idea at what point these westbound DFW/IAH flights are contacting San Francisco on the SP frequencies ? I'm just trying to pin down the CEP boundary.

Before this week Its been over 10 years since the last time I have monitored the SP area but from what I have heard recently it sounds like flights further west operating from Australia/New Zealand to/from LAX/SFO switch between the SP to CEP areas crossing 20N latitude (northbound using 5574 primary, 3413 secondary, at 10Z-11Z).

And has San Francisco changed their SP frequencies over the last few years ? I think I heard a handoff to 5652 and 8870 ?

AS
 
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majoco

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There was a change recently, adding a lot of frequencies to Pacific stations by ARINC but fortunately we were left alone!
3467, 5643, 8867, 13261, 17904 khz.
 

AirScan

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3467, 5643, 8867, 13261, 17904 khz
Between 1200UTC-1400UTC there is a lot southbound traffic from the US west coast transitioning between San Francisco and Auckland airspace.

I was monitoring 3467, 5643 and 8867 during this time expecting to hear these flights as they checked on with Auckland crossing the FIR boundary. HF conditions were good on all 3 frequencies as I could hear Auckland as well as all the other ground stations (Brisbane, Nadi, Tahiti, San Francisco) and the aircraft they were working. I could hear aircraft northbound checking on with San Francisco in the same area, but out of about 10 southbound flights I only heard 1 checking on with Auckland on 5643. Wondering if Auckland uses another frequency or how I could have missed those flights ?

And back to the original topic, at 1137UTC today caught ANZ028, AKL-IAH, working San Francisco on 5643 as they crossed the FIR boundary with Tahiti for a SELCAL check. They were then told to contact San Francisco on 5574 when crossing 20N. I was monitoring 5574 and 8843 (the secondary) during the time they crossed 120W and 20N and did not hear anything from the flight. Conditions were good, San Francisco and aircraft were all coming in about 3/3 during this time.

AS
 

invergordon

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HF conditions were good on all 3 frequencies as I could hear Auckland as well as all the other ground stations (Brisbane, Nadi, Tahiti, San Francisco) and the aircraft they were working. I could hear aircraft northbound checking on with San Francisco in the same area, but out of about 10 southbound flights I only heard 1 checking on with Auckland on 5643. Wondering if Auckland uses another frequency or how I could have missed those flights ?AS
I think they will all be handed off on CPDLC, certainly the ANZ flights into Auckland OCA will not require an HF call or SELCAL check and I suspect that other airlines won't unless company policy states so.
 

AirScan

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Okay I see I am behind the times. After further Googling I see that Auckland is now using a CPDLC/SATCOM system that does not require a HF backup check. From what I have NOT heard on HF, in addition to QFA and ANZ, it looks like VOZ, UAL, AAL are also using this system.

So far I've only heard of it in the Auckland area, probably Australia too (haven't checked lately), it will be interesting to watch how soon this is implemented in other areas. It doesn't seem to be the case across the North Atlantic yet, or maybe just a small amount of aircraft are equipped ? The end of an era, no more aviation HF :-(
 
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majoco

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....but I still hear quite a few operators, especially Singapore, checking in, getting a Selcal check and then Auckland says "continue with CPDLC" - perhaps it's a 'belt and braces' company thing.
 

AirScan

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I still hear quite a few operators, especially Singapore, checking in, getting a Selcal check and then Auckland says "continue with CPDLC" - perhaps it's a 'belt and braces' company thing.
Seems to only apply to aircraft that are equipped with the latest/approved SATCOM systems. I've been searching for an official document that specifies exactly what equipment/authorization is required to waive the requirement to monitor HF as a backup.

Some info here as it pertains to the USA/FAA

HF Requirement

Still searching for something more specific to Auckland airspace.
 

AirScan

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Found something official.

New Zealand AIP 3.4-10

Datalink Communications

3.3.10 Auckland Oceanic Control has installed an automated Oceanic Control System (OCS) that is fully FANS 1/A compliant. The Logon address is “NZZO”.

3.3.11 Auckland Oceanic control will accept:
(a) Automatic Dependent Surveillance — Contract (ADS-C) position reports; and
(b) Controller Pilot Datalink Communications (CPDLC). SELCAL checks by CPDLC equipped aircraft are not required when entering NZZO FIR. Aircraft filing a SELCAL code in item 18 of their flight plan will be assumed to have a serviceable SELCAL and to be maintaining a SELCAL watch on the HF primary frequency advised in the appropriate MONITOR instruction passed by the transferring CPDLC authority.

Note: There is no requirement for FANS 1/A aircraft entering NZZO FIR to contact Auckland Radio for a SELCAL check.
http://www.aip.net.nz/pdf/GEN_3.4.pdf

AS
 
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