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Loss Of All VHF Comms On MS Flight  
User currently onlineFaro From Egypt, joined Aug 2007, 1613 posts, RR: 0
Posted (5 years 7 months 6 days 18 hours ago) and read 5065 times:

ACARS message copied today at www.acarsd.org:

ACARS mode: 2 Aircraft reg: SU-GCJ [Airbus A332]
Message label: SA Block id: 8 Msg no: S59A
Flight id: MS0799 [CAI-CDG] [Egyptair]
Message content:-
LOST VHF AT 112318 ACTIVE COMMS SATCOM+HF

What kind of hitch can lose you all your VHF transceivers at the same time and leave SATCOM and HF intact?

Also, are all airfields equipped with SATCOM/HF installations? From what I recall for HF stations in particular, you need huge, outstretched rhombic antennas to maximise signal quality and big open spaces all around them to avoid interference.

Faro

[Edited 2009-05-19 07:38:00]


The chalice not my son
30 replies: All unread, showing first 25:
 
User currently offlineManuCH From Switzerland, joined Jun 2005, 3012 posts, RR: 46
Reply 1, posted (5 years 7 months 6 days 18 hours ago) and read 5059 times:
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I have no idea what could have caused this. But what I can tell you is that most airfields will *not* have HF for sure. AFAIK HF is only used for trans-oceanic communications. And SATCOM isn't usually used to communicate with airports either.

This could become interesting. How is the airplane communicating, for example, with the tower? Via company on ACARS?

Edit: actually ACARS has ATC datalink messages. But are there any airports supporting them, or are they only thought for oceanic clearances?

[Edited 2009-05-19 07:33:44]


Never trust a statistic you didn't fake yourself
User currently offlineDescendVia From , joined Dec 1969, posts, RR:
Reply 2, posted (5 years 7 months 6 days 18 hours ago) and read 5046 times:

Quoting ManuCH (Reply 1):
But what I can tell you is that most airfields will *not* have HF for sure. AFAIK HF is only used for trans-oceanic communications

While this is true there is a lot of towers which has a military channel that is HF.

Quoting ManuCH (Reply 1):

This could become interesting. How is the airplane communicating, for example, with the tower? Via company on ACARS?

Edit: actually ACARS has ATC datalink messages. But are there any airports supporting them, or are they only thought for oceanic clearances?

I'm sure this plane has CPDLC so no big fuss for so equipped FIRs. Other then that they probably either are using the available HF channels or have SAT tied into each FIR. A lot ACARS systems don't actually have a feed to ATC just the company.

Worst comes to worst, they would just land as soon as practicable and get light gun signals from the tower (if so equipped in this region) in VMC.

[Edited 2009-05-19 07:48:03]

User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 3, posted (5 years 7 months 6 days 17 hours ago) and read 5032 times:



Quoting DescendVia (Reply 2):
While this is true there is a lot of towers which has a military channel that is HF.

Don't think so.....


User currently offlineKELPkid From United States of America, joined Nov 2005, 6428 posts, RR: 3
Reply 4, posted (5 years 7 months 6 days 17 hours ago) and read 5024 times:

Time to squawk 7600 and hold until your arrival time?  eyebrow  Wonder if the captain and/or FO carry a handheld transceiver with them...  Wink


Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineDaBuzzard From Canada, joined Sep 2007, 136 posts, RR: 0
Reply 5, posted (5 years 7 months 6 days 17 hours ago) and read 5011 times:



Quoting ManuCH (Reply 1):
AFAIK HF is only used for trans-oceanic

We use hf quite a bit in the far north, pretty common to not be able to reach anyone on the vhf. Our flight crews also carry a sat phone, guess you could call the tower's landline in a pinch  Smile

Quoting Faro (Thread starter):
What kind of hitch can lose you all your VHF transceivers at the same time and leave SATCOM and HF intact?

Only common point I can think of on our (much smaller) aircraft would be the audio selector panel. No idea how the 'Bus is configured but it must have some way of selecting what nav/comm audio gets routed to/from the headset/mic.


User currently offlineDescendVia From , joined Dec 1969, posts, RR:
Reply 6, posted (5 years 7 months 6 days 15 hours ago) and read 4955 times:



Quoting PhilSquares (Reply 3):
Don't think so..

MLS23
ILS05

Whatcha call 291.1 for Pope tower or 257.7 for MBS tower  Wink


User currently offlinePihero From France, joined Jan 2005, 4672 posts, RR: 77
Reply 7, posted (5 years 7 months 6 days 15 hours ago) and read 4947 times:
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Quoting DescendVia (Reply 6):
Whatcha call 291.1 for Pope tower or 257.7 for MBS tower

UHF frequencies.



Contrail designer
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 8, posted (5 years 7 months 6 days 15 hours ago) and read 4941 times:



Quoting DescendVia (Reply 6):
Whatcha call 291.1 for Pope tower or 257.7 for MBS tower

As has been pointed out by Pihero, those are UHF frequencies. Every commercial aircraft I have flown has VHF only! They are a far cry from HF frequencies!  banghead 


User currently offlineSpudsmac From United States of America, joined Feb 2008, 307 posts, RR: 0
Reply 9, posted (5 years 7 months 6 days 13 hours ago) and read 4899 times:

HF is actually lower than VHF and of course UHF here is a table that goes over that from my avionics course:

0-30 KHz, Extremely Low Frequency (ELF)
3-30 KHz, Very Low Frequency (VLF)
30-300 KHz, Low Frequency (LF)
300 KHz-3 MHz, Medium Frequency (MF)
3-30 MHz, High Frequency (HF)
30-300 MHz, Very High Frequency (VHF)
300-3 GHz, Ultra High Frequency (UHF)
3-30 GHz, Super High Frequency (SHF)
30-300 GHz, Extremely High Frequency (EHF)


User currently offlineZappbrannigan From Australia, joined Oct 2008, 247 posts, RR: 0
Reply 10, posted (5 years 7 months 6 days 11 hours ago) and read 4867 times:



Quoting ManuCH (Reply 1):
This could become interesting. How is the airplane communicating, for example, with the tower? Via company on ACARS?



Quoting KELPkid (Reply 4):
Time to squawk 7600 and hold until your arrival time? eyebrow Wonder if the captain and/or FO carry a handheld transceiver with them...



Quoting DescendVia (Reply 2):
Worst comes to worst, they would just land as soon as practicable and get light gun signals from the tower (if so equipped in this region) in VMC.

Yep, can't speak for the problem itself, but there are very specific procedures for loss of comms in controlled airspace - there's not a lot of "gee what do we do now, I suppose we should hold for a bit then land".

Here, in a nutshell, the procedures are basically squawk 7600, then continue flight and descent as per flight plan/SOPs, descend as appropriate for "the most suitable approach" (straight out of the book), and in many cases wait for the green light from the tower, as mentioned.

In the aircraft I fly (i.e. not big jets), when our VHF goes bang (as has happened to me twice before), we listen out on specific NDB frequencies for instructions as well.

The last time this happened to me on arrival, we got our clearance to enter controlled airspace, and our visual approach clearance, via cell phone from the tower. About one mile out - green light, all good. Ahhh, the wonders of GA.


User currently offlineDescendVia From , joined Dec 1969, posts, RR:
Reply 11, posted (5 years 7 months 6 days 10 hours ago) and read 4834 times:



Quoting Pihero (Reply 7):



Quoting PhilSquares (Reply 8):

Boy I sure dropped that ball  Embarrassment

As I trued off my computer to go flying, I was like I bet those are actually UHF freqs  Smile O well......


User currently onlineFaro From Egypt, joined Aug 2007, 1613 posts, RR: 0
Reply 12, posted (5 years 7 months 6 days ago) and read 4764 times:



Quoting Zappbrannigan (Reply 10):
Here, in a nutshell, the procedures are basically squawk 7600, then continue flight and descent as per flight plan/SOPs, descend as appropriate for "the most suitable approach" (straight out of the book), and in many cases wait for the green light from the tower, as mentioned.

Interesting, is this a green flare or a directed light source like VASI's and the like? Is it visible in full sunlight? Anyone know of any pix in the database of this "greenlight"?

Faro



The chalice not my son
User currently offlineKELPkid From United States of America, joined Nov 2005, 6428 posts, RR: 3
Reply 13, posted (5 years 7 months 5 days 12 hours ago) and read 4668 times:



Quoting Faro (Reply 12):
Interesting, is this a green flare or a directed light source like VASI's and the like? Is it visible in full sunlight? Anyone know of any pix in the database of this "greenlight"?

Faro

In the US at least, it's a "light gun", which is a very bright incandescent lamp which can be triggered on and off (blinked) or the color changed from white to green or red, or both. The gun has a Fresnel lens, so that when it's pointed at your aircraft, you know it...it works great in daylight, too.

Similar to this: http://www.atiavionics.com/products.html

except that in most US air traffic control towers, the light gun is permanently mounted in the tower cab window (but is free to swivel around...).



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently onlineFaro From Egypt, joined Aug 2007, 1613 posts, RR: 0
Reply 14, posted (5 years 7 months 5 days 9 hours ago) and read 4620 times:



Quoting Faro (Thread starter):
LOST VHF AT 112318 ACTIVE COMMS SATCOM+HF

What kind of hitch can lose you all your VHF transceivers at the same time and leave SATCOM and HF intact?

To get back to the initial question, what sort of redundancy is typically afforded by the VHF comms set-up? Are all transceivers located separately from one another? Are antennae distributed about the fuselage? Can a problem with the Audio Selector Panel really lose you all your VHF's?

Faro



The chalice not my son
User currently offlineKELPkid From United States of America, joined Nov 2005, 6428 posts, RR: 3
Reply 15, posted (5 years 7 months 5 days 9 hours ago) and read 4607 times:



Quoting Faro (Reply 14):
To get back to the initial question, what sort of redundancy is typically afforded by the VHF comms set-up? Are all transceivers located separately from one another? Are antennae distributed about the fuselage? Can a problem with the Audio Selector Panel really lose you all your VHF's?

Faro

You know, a thought just sprung to mind here: doesn't ACARS work over VHF radio? (I thought it did-someone can correct me if I'm wrong here....). How do you get an ACARS message out if your COMM stack is kaput?  scratchchin  I guess you could have a company aircraft that you're on frequency with on HF relay something for you...  Wink



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 16, posted (5 years 7 months 5 days 2 hours ago) and read 4560 times:



Quoting KELPkid (Reply 15):
You know, a thought just sprung to mind here: doesn't ACARS work over VHF radio?

Yea, ACARS works over VHF. However, depending on the carrier, it can also work over HF or SATCOM. For most long haul carriers, the ACARS set up is VHF as the default, then either ACARS or HF as a back up. Or in some cases, both SATCOM and HF would be tried.

Quoting Faro (Reply 14):
To get back to the initial question, what sort of redundancy is typically afforded by the VHF comms set-up? Are all transceivers located separately from one another? Are antennae distributed about the fuselage? Can a problem with the Audio Selector Panel really lose you all your VHF's

Generally the transceivers are located in the lower E&E compartment. The antennae are located in various places. The VHF1 and 3 are normally located on the lower fuselage while VHF 2 is located on the top of the fuselage. And, I suppose the ACP could take out all the VHF but it would most likely take out the intercom and all other radios with it. Anything is possible.


User currently offlineThirtyEcho From United States of America, joined Dec 2001, 1659 posts, RR: 1
Reply 17, posted (5 years 7 months 5 days ago) and read 4542 times:

Interesting that we have been ready for lost com since about 1935: "Airspiffy 123 is cleared to Bugtoe as filed, climb and maintain 6000, expect FL190 10 minutes after departure..."

Some winter's night, curl up in a chair by the fire and read the AIM on lost com and be amazed. You can get from A to B in total silence and total safety, even in IMC.


User currently offlineA10WARTHOG From United States of America, joined Jul 2004, 325 posts, RR: 0
Reply 18, posted (5 years 7 months 4 days 11 hours ago) and read 4460 times:

If your ACP goes out, you will lose all comm (VHF, HF, SATCOM, PA, etc) I would doubt it that it was an ACP, Plus you would have the other ACP that you could use to TX.

I would need wiring diagrams to see if you had anything common between the three systems. Your wiring is different, between the three system. The only thing i could see common with what little info I could find on the web is the Audio management unit (I think that is what airbus calls it). Maybe part of the box failed.


User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 19, posted (5 years 7 months 4 days 11 hours ago) and read 4456 times:



Quoting Faro (Thread starter):
What kind of hitch can lose you all your VHF transceivers at the same time and leave SATCOM and HF intact?

In doing a little research, the ACARS message is a ACARS generated msg that indicates it has lost the VHF link and will now send via SATCOM or HF. There was no complete loss of VHF radios.


User currently onlineFaro From Egypt, joined Aug 2007, 1613 posts, RR: 0
Reply 20, posted (5 years 7 months 3 days 23 hours ago) and read 4402 times:



Quoting PhilSquares (Reply 19):
In doing a little research, the ACARS message is a ACARS generated msg that indicates it has lost the VHF link and will now send via SATCOM or HF. There was no complete loss of VHF radios.

Thanx, that settles the matter. Was myself surprised that this indication can be found so easily in an ACARS message. A full VHF comms failure must, happily, be a much rarer occurence.

Faro



The chalice not my son
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 21, posted (5 years 7 months 3 days 19 hours ago) and read 4370 times:

That's interesting since our ACARS has a priority selection. It picks VHF first then depending on whether an HF radio is in data mode will select it next then SATCOM. We do not run any HF in data if SATCOM equipped therefore HF isn't a player. All of our -11s are so equipped. I would assumme most all jets are so packaged.
Loss of all comms would be rare since the VHF radios are on different busses. I did have a mike stick one night right on T/O that disabled all radios until we found the culprit. It took several minutes since we could still hear ATC and THOUGHT we were transmitting for a moment or two. When we realized the problem we started searching for the stuck button but considering there are 8 between the capt & f/o it took a few more min. We started unplugging all mikes that could be unplugged and finally found the f/os yoke switch as the bad one.


User currently offlineKELPkid From United States of America, joined Nov 2005, 6428 posts, RR: 3
Reply 22, posted (5 years 7 months 3 days 17 hours ago) and read 4351 times:



Quoting CosmicCruiser (Reply 21):
did have a mike stick one night right on T/O that disabled all radios until we found the culprit. It took several minutes since we could still hear ATC and THOUGHT we were transmitting for a moment or two. When we realized the problem we started searching for the stuck button but considering there are 8 between the capt & f/o it took a few more min. We started unplugging all mikes that could be unplugged and finally found the f/os yoke switch as the bad one.

 rotfl  Glad to hear that it's not just us GA drivers who deal with stuck mic switches. Don't your audio panels have a light that comes on, though, when you're transmitting?



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 23, posted (5 years 7 months 3 days 17 hours ago) and read 4350 times:



Quoting CosmicCruiser (Reply 21):
That's interesting since our ACARS has a priority selection.

Ours do too. But if you get a VHF No Comm, it will sent a test message via either SATCOM of HF date burst that checks the comm in that mode. Ours are set for VHF, SATCOM and then HF Data Burst.


User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 24, posted (5 years 7 months 3 days 17 hours ago) and read 4343 times:



Quoting KELPkid (Reply 22):
Don't your audio panels have a light that comes on, though, when you're transmitting?

No but if the mike is keyed for a certain number of seconds you hear a tone beep which we heard right as the power was being pushed up and I didn't think much about it. We didn't hear it again but there was lots of radio activity and we may not of heard it.

Quoting PhilSquares (Reply 23):
Ours are set for VHF, SATCOM and then HF Data Burst.

Sounds like ours. We actually don't put any HF in data mode if there's SATCOM because of something to do with HF and FANS.


25 PhilSquares : Ours is the same way. I don't recall ever having it default to the HF mode since SATCOM is extremely reliable. But, we do see SATCOM all the time.
26 CosmicCruiser : Next best thing since sliced bread!! Even the SATCOM radio calls are like talking to your next door neighbor. I heard about a pilot that turned his b
27 ManuCH : All this IMHO still leaves the question open on what an *airliner* would do without VHF. Let's assume a 747 flying into JFK. I know about GA procedur
28 PhilSquares : First of all, the odds are extremely remote that this would ever happen. But, all you have to do is send a ACARS message to dispatch, they will then
29 Zappbrannigan : Phil has obviously answered your question - but I thought I'd make the point that these aren't "GA procedures" - they're required procedures for all
30 DescendVia : No need to figure what he "might" do, the stuff is there for a reason. Emergencies tend to disrupt operations and this is why the EFC or ETA is so im
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