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Air France A330 accident

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Air France A330 accident

Old 4th Jun 2009, 07:58
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Air France A330 accident

Hi All,



At this early stage, by looking at the wreckage floating on the water, is it possible to determine whether the AF A330-200 experienced an inflight Break Up or It breaks up on impact with the water?

If, it was an inflight Break Up, would that be possible to predict whether it is an excessive aerodynamic force induced Break Up, or if the Break Up was caused by - i.e. Bomb?

Specific to the A330 200 operated by Air France, does anyone knows if the ACARS also transmit excessive G force experienced by the aircraft?

I haven't flown any Airbus FBW nor have I got any appreciable knowledge of the flight control logic, according to what I gather from the media and some posts on the AF330 Thread, there have been discussion about the ACARS sending "electrical fault" message, in this case, would the fault degrade the flight control system so much as to the crew lost the flight envelope protection?

Thank you all!

SS
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Old 4th Jun 2009, 10:22
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Originally Posted by Silver Spur View Post
Hi All,



At this early stage, by looking at the wreckage floating on the water, is it possible to determine whether the AF A330-200 experienced an inflight Break Up or It breaks up on impact with the water?
No, you'd need to get the bits into a lab, and probably need a reasonably number of the metal bits into a lab. That would take some time, since most of those don't float.


If, it was an inflight Break Up, would that be possible to predict whether it is an excessive aerodynamic force induced Break Up, or if the Break Up was caused by - i.e. Bomb?
I think you meant "e.g.", but I'm just being picky. Yes, the tear marks on the fracture surface look quite different from a fuel explosion, overstress, or high explosive. Also, there's a good chance of some residues that can indicate whether an explosive was present and if so which one.


Specific to the A330 200 operated by Air France, does anyone knows if the ACARS also transmit excessive G force experienced by the aircraft?
No idea.

I haven't flown any Airbus FBW nor have I got any appreciable knowledge of the flight control logic, according to what I gather from the media and some posts on the AF330 Thread, there have been discussion about the ACARS sending "electrical fault" message, in this case, would the fault degrade the flight control system so much as to the crew lost the flight envelope protection?
We'd need a lot more information than has been released by Air France to answer that.

G
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Old 4th Jun 2009, 19:04
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Airframe strength/controllability

The R&N forum on the AF 447 disaster is replete with statements by pilots contributing to the forum that flight through severe CBs is incredibly dangerous, and to be avoided at all costs. My question (as an ignorant SLF) is this. Every hurricane season, the USAF and NOAA fly planes through the middle of these storms to gauge their strength, etc. These planes are Lockheed C-130 Hercules, P-3 Orions, and even Gulfstream GIV's. See: Hurricane Hunters Association and NOAA's Hurricane Hunters .

Clearly, these are not "certain death" missions. How do these facts square with the R&N statements about the inadvisability of commercial aviation encounters with turbulent weather. Is it: (a) hurricane hunting is extremely dangerous; (b) the aforementioned planes are more robust than commercial Airbus and Boeing products; (c) hurricane hunter crews have more refined skills for this task; (d) the turbulence found in hurricanes is less or more consistent than the turbulence found in major CBs; (e) the commercial planes and crews are quite adequate, but the PAX can't abide by the ride; or (f) none of the above?

Again, I'm not trying to point any fingers, just interested in resolving the apparent disconnect. Thanks.
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Old 4th Jun 2009, 19:16
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Have heard on "good and reliable" authority:

"Aircraft hit CB...experienced +/- 100 knot windshear. Autopilot disconnected ...Power failure to screens...Airframe breeched...Rapid decompression...Followed by flight control losss......Entire event 14 minutes"

Must have been a long 14 minutes !!
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Old 4th Jun 2009, 19:48
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SeenItAll -
The main difference between your hurricane hunters and commercial aircraft penetrating severe weather is.....PASSENGERS. The airframe will normally withstand much more than the pasengers can endure. And, the pilots and crew of those hurricane hunter aircraft are strapped in, not wondering about the cabin or failing to "keep their seat belt fastened" even while seated !

Also, the convective forces are far greater in a thunderstorm, I believe, than in a hurricane. And, the imbedded thunderstorms within any hurricane are avoided I'm sure by those aircraft.
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Old 4th Jun 2009, 19:54
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Whilst I don't want to be accused of added to unsubstantiated facts, I find it incredible that an experienced Air France Captain would knowingly fly into an area of CB activity - especially at cruising altitude.

With three pilots on board I presume one was a 'cruise pilot'.

Assuming route forecasts were obtained and that the weather radar was working the question has to arise as 'why did they enter an area of CB activity?'

Was the Captain in the flight deck or were the First and Second Officer in control at the time? If so was their relative inexperience an issue?

All speculation I'm afraid, but in common with all other pilots I can't imagine anyone knowingly flying directly into a known area of bad weather?

As for the 'bomb theory', the only possible (and wildly unsubstantiated) cause I can think of is a connection with the 'Brazilian Prince' who was aboard. Unfortunately this borders on fantasy and would prove that someone has watched too much TV (Airport 77?).

The 'reality' of the situation may be ill-advised entry into an area of CB activity.

If this is the case, then Air France will no doubt be awaiting the onslaught of claims from relatives of the victims.

Amongst all the speculation it has to be said that I can't imagine the pain and grief this accident has caused. Having flown the Atlantic as so many of us have, the prospect of a catastrophe of this nature is beyond belief.

SITW
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Old 4th Jun 2009, 19:58
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Originally Posted by Genghis the Engineer
Also, there's a good chance of some residues that can indicate whether an explosive was present and if so which one.
While residues are present after an explosion and often they are the best evidence, numerous past events would shows three key facts.
  • Water can destroy the evidence
  • Evidence can get tainted in rescue operations
  • Traces of explosives can be present on an aircraft and can be unrelated to the accident.
TWA-800 investigation can show examples of all 3 claims, and for this reason I would look for other evidence first. Tear marks on fracture surface, fault tree analysis, etc. can help. Sequence of events can also help to rule out some possibilities, and for this reasons ACARS messages can be important.

Originally Posted by Silver Spur
Specific to the A330 200 operated by Air France, does anyone knows if the ACARS also transmit excessive G force experienced by the aircraft?
I would find it extremely unlikely to see any such ACARS messages. While ACARS messages are one of the few evidence that can be used in the accident investigation, ACARS isn't designed for this purpose.

Originally Posted by SeenItAll
My question (as an ignorant SLF) is this. Every hurricane season, the USAF and NOAA fly planes through the middle of these storms to gauge their strength, etc.
It is quite different to fly above the storms, and measure the pressure in the eye, if the whole staff on the plane is prepared for the worst, experience, trained, strapped in. And you can also say that the hurricane is different...
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Old 4th Jun 2009, 20:32
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Silver Spur

I haven't flown any Airbus FBW nor have I got any appreciable knowledge of the flight control logic, according to what I gather from the media and some posts on the AF330 Thread, there have been discussion about the ACARS sending "electrical fault" message, in this case, would the fault degrade the flight control system so much as to the crew lost the flight envelope protection?
As Gengis said we all need more information as to the sequence of events etc. However, for your information the flight controls will reconfigure with two or more related failures, for example two ADR failures etc. would put the aircraft in Alternate law which would remove the protections.
The "electrical fault" ACARS message quoted would have more information attached which we are not privy to yet unless we have "good and reliable authority" feeding us the information....

Last edited by Che Guevara; 5th Jun 2009 at 07:14.
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Old 4th Jun 2009, 20:35
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SpannerInTheWerks -

You might not be able to "imagine anyone knowingly flying directly into a known area of bad weather?".....but the fact is, it has happened before on too many occasions. As to the Captain taking his break at the time, I find THAT hard to believe if he knew they were going to be in an area of storms. Unless, that is, he told the relief crew to avoid those areas and they didn't for some reason.

About all we can do is speculate unfortunately, because the chances of recovering any meaningful data does not look good at this point.

Speculation-wise, I'd say that weather was a factor as was computerized flight controls.
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Old 4th Jun 2009, 20:38
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turbulence penetration speed

does anyone have any information on what the source of the "flew too slow" message was, that was on the media today?
German national radio (Deutschlandfunk) even reported that Airbus had issued an advisory, "reminding pilots not to fly too slow when entering adverse weather" they said.
Has anyone seen that?
What are the critical speeds for a 330 at the given conditions for maximum mach number, stallspeed and turbulence penetration?
Also, if there is any creedence to be given to these report, has there been any data that would allow calculating the aircraft's speed at the time of the event? Do the acars messages contain gps location and timestamp?
Somehow, given the unfolding of events that those messages indicate, I can't quite believe that structural failing was at the beginning of the chain of events. Surely, if the aircraft structure had been damaged enough to render such vital systems inop within short time, a hull breach/decompression would have been recorded early on, not just after four minutes.

Btw, it's interesting to see how most of the "experts" talking to media seem to be retired somethings. Mechanics, pilots, just about anything, but all retired. It seems that those who still are in the business often answer the right thing: "we don't know" - which, of course, isn't acceptible if you're writing for a 1st page headline.
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Old 4th Jun 2009, 20:56
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SoaringTheSkies

The turbulence penetration speed on the 332 at that level is MACH .80 and MMO is .86
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Old 4th Jun 2009, 22:11
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Air France Flt 447

Normally the ACMS will transmit to their operations control any exceeded limits which are normally tailored by the airlines for their operational requirements ( response to your ACARS transmissions). Something that boggles me is that in todays news they are hinting towards pilot error for stalling the airplane, which does not make sense as these airplanes have alpha floor protection ( stall Protection) which with all its PRIM's and SEC's working would not allow it to reach that situation.
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Old 4th Jun 2009, 23:36
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jetstream00,

when you go after several failures to direct law you lost all protections so...
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Old 4th Jun 2009, 23:56
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Jigsaw!!!!

How about looking at the Technical side of failures????

I posted previous comment on Composite & Lightening discussion but seems a bit lost there....

Just a few things which are bugging me from what I know about A330s and my experience on them.....

I am MORE interested in that ACARS message.....if that was sent that means there was power available in that system from the BUS2... that means there was full power supply from BUS2 feeding the other electrical buses......

ALSO....IF ACARS were still gathering and sending data about the failures then ACMS/CMC was fully functional, monitoring all the relevant systems and reporting subsequent failures....

Data Transmission

The Data Transmission system comprises:

Aircraft Communications Addressing and Reporting System (ACARS)

The ACARS management unit allows management of the data transmitted to the ground (SDAC, FWC, AIDS, CMS, FMGEC) and entered by the crew. It also allows reception, printing and display of ground messages on the MCDU.
These data are transmitted through the VHF 3 system (or through the SATCOM system if installed).

Gate Link

The system allows a connection between the Aircraft Information Network System (AINS) and the airline ground based information system.

Its description is made in the Description/Operation of the AINS (Ref. 46-11).


Air-to-ground calls
When a call is initiated by an airborne subscriber, the AES sends signals to the GES, using the Rd-Channel. When the GES receives the call request, it assigns a pair of C-Channels, for a voice call, or reserves time on a T-Channel, for long-duration data transmissions. The call can then go through.
The assigned channels are reserved for as long as the call is in progress. The sequence used to initiate the call is automatic and transparent to both the originator and the receiver of the call.


ALSO......looking at the Power distribution schematic of this a/c everything essential is always powered (thats why its called essential)......


Cutting to the chase.....I am looking at these units......


Electrical Contactor Management Unit (ECMU)

The system consists of two separate equipment called ECMU1 and ECMU2.
Their functions are similar but the ECMU1 manages only side 1 contactors and ECMU2 manages only side 2 contactors.

Each ECMU receives the following signals:
-
orders from the GCUs and the GAPCU,
status of the main AC and DC generation contactors,
voltage of the main AC and DC busbars.

The two main functions of the ECMU are:

Operational function:

control of the AC/DC main contactors,

control of the galley shedding,

on ground, control of the transfer between the various electrical power sources (IDG, APU, EXT PWR) in order to avoid any break of power (NBPT),

control of AC/DC ground service busses,

control of Inadvertent Paralleling Trip (IPT).

BITE function

monitor and test the ECMU together with its peripheral circuits,
collect the failures and store the corresponding fault code in the Non Volatile Memory (NVM),

transmit the failure message to the Central Maintenance Computer (CMC) through an ARINC 429 bus.


In addition, in case of ECMU failure, a fault warning message is generated to the Engine/Warning Display (EWD).

Transfer circuit

The Bus Transfer Contactors (BTC)s and the System Isolation Contactor (SIC) are automatically controlled by the ECMUs. They enable supply of all the aircraft electrical network or half of it.
The supply only depends on the availability of one of the five power sources: GEN1, GEN2, APU GEN, EXT PWR A and B.
The control of the BTCs also depends on the availability of these sources and the correct condition of each network.

Operation of BTC1

The BTC1 closes, if no interlock conditions exist on the GCU1:

when the GEN1 is not available, in order to supply the network 1 (AC BUS 1) from another power source (GEN2, APU GEN, EXT PWR A or EXT PWR B),

to supply the network 2 from GEN1 if the GEN2, APU GEN EXT PWR A and EXT PWR B are not available.

Operation of BTC2

The BTC2 closes if no interlock conditions exist on the GCU2:

when the GEN2 is not available in order to supply the network 2 from another power source (GEN1, APU GEN , EXT PWR A or EXT PWR B),

to supply the network 1 from the GEN2 if the GEN1, APU GEN , EXT PWR A and EXT PWR B are not available.

Latching logic of the BTCs

The BTC1 is latched open if a "GLC1 welded" failure or a short circuit not clarified by C/B tripping occurs at level of GEN1 channel.
The same latching logic is used for BTC2.

System Isolation Contactor (SIC)

The SIC closes automatically:

when the GEN2 and EXT PWR A are not available and APU GEN is available in order to supply network 2 from the APU GEN,

when the GEN1 and APU GEN are not available and EXT PWR A is available in order to supply network 1 from the EXT PWR A,

when the GEN2, APU GEN, EXT PWR A are not available and GEN1, is available in order to supply network 2 from the GEN1,

when the GEN1, APU GEN, EXT PWR A are not available and GEN2, is available in order to supply network 1 from the GEN2.

Priority order of power supply

Each network (1 or 2) is supplied in the following priority order:

1XP = IDG1/APU GEN/EXT PWR B/EXT PWR A/IDG2,
2XP = IDG2/EXT PWR A/APU GEN/EXT PWR B/IDG1.

Isolation of the two sides

The isolation of the two sides is possible by action on the BUS TIE pushbutton switch. This control is located on the ELEC control panel 235VU, cockpit overhead panel.

No Break Power Transfer (NBPT)

This function is managed by the ECMUs. It prevents busbar power interruption due to electrical power supply source transfer on ground in normal configuration.
The ECMU receives information from the main AC contactors, each GCU and the GAPCU, to perform this function.
No break power transfer occurrences are permitted between:

any external power and the APU generator,
any IDG and any external power,
any IDG and the APU generator.

Distribution

The alternating current distribution network comprises two independent sections.

Network 1

Network 1 mainly includes the AC BUS 1, the AC ESS BUS and the AC SHED ESS BUS which are three-phase, 115 VAC/400 Hz busses.
The AC BUS 1 supplies the essential busses in parallel. The AC ESS BUS also delivers 26 VAC/400 HZ power supply through a 115/26 VAC transformer.
In the event of the AC BUS 1 loss, the AC ESS BUS and AC SHED ESS BUS are automatically restored by the direct transfer of power supply from the AC BUS 2.
In case of loss of the AC essential busses, FAULT legend on the AC ESS FEED pushbutton switch comes on : this P/BSW enables to transfer the AC essential busses supply from AC BUS 1 to AC BUS 2, in particular when the loss of the AC essential busses normal supply does not result from AC BUS 1 loss.
If there is loss of AC BUS 1 and AC BUS 2 (emergency configuration), the AC ESS BUS and AC SHED ESS BUS are restored via the CSM/G driven by the Green hydraulic power. In case of RAT operation, the AC SHED ESS BUS is automatically shed.

Network 2

Network 2 comprises the AC BUS 2 which is a three-phase, 115 VAC/400 Hz bus.
The AC BUS 2 also delivers 26 VAC/400 Hz power supply through a 115/26 VAC transformer.

I somehow do not agree with so-called assumption of "short circuit" starting this chain of failures.......I think the only way it can be done is by crew intervention (eg turning the wrong BTB p/b off) and stop the serviceable bus feeding the u/s Bus.....which in turn will start the sequence of power failures to these computers......

Still trying to figure out.........any A330/340 guys would like to add????




MrFixer!!! is offline  
Old 4th Jun 2009, 23:56
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Due to the sensitivity of the matters in discussion, I would like for all of us to keep the sensational and overtly speculative things in R&N or other suitable places.

Technical-related considerations are fine here.

So far as the weather at the time ... and, for those who are interested, you might like to read Tim Vasquez' analysis of the weather - hyperlink at the top of the home page.

Makes for very sobering reading.

As we all understand (I hope) the Design Standards and the certification process consider a very wide range of reasonably expected circumstances. However, Mother Nature can still cause a few tricks to be pulled out of Pandora's box ...
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Old 5th Jun 2009, 00:01
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sinsin

Have heard on "good and reliable" authority:

"Aircraft hit CB...experienced +/- 100 knot windshear. Autopilot disconnected ...Power failure to screens...Airframe breeched...Rapid decompression...Followed by flight control losss......Entire event 14 minutes"

Must have been a long 14 minutes !!
Not really a long 14 minutes necessarily, the rapid decompression at the probable max operating altitude to fly over weather like this was probably violent enough to knock most people out rather quickly.

The distance of the debris field will suggest at what altitude the airframe breach occured giving insight into how long most were consious.
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Old 5th Jun 2009, 01:08
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with all its PRIM's and SEC's working would not allow it to reach that situation
When you have lost the Prims and running on secs all bets are off (and most control law protection).

Interesting about the reported "electrical" failures, as the satcom (probably outside vhf range) and data link atsu were still working, ie. must have still had ac power.
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Old 5th Jun 2009, 02:03
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ALSO......looking at the Power distribution schematic of this a/c everything essential is always powered (thats why its called essential)......
Caveat: About the A330 I know nothing.

OK, in general terms aircraft electrical systems are designed to fail in such a manner that the core of the system is maintained. i.e. battery for essential DC and an inverter for essential AC. Pretty much every aircraft I am familiar with has something like that sitting in the middle of the system, to give you half an hour or so to either get a gen going or land.

Then we add some emergency power generation, maybe a RAT, or a hydraulic driven Gen, to allow us to fly indefinitely, albeit substantially degraded.

Then we add an APU gen, which, depending on the flight envelope and type will be able to run a good chunk of the aircraft.

Then we have the main engine gens that run the whole shooting match when all is well.

Obviously theres lots of variations on the theme, but when you get right down to it most modern electrical systems are conceptually identical.

As such we tend to get into the habit of assuming the system will fail in a manner its designed to cope with. Like in the Sim. Ho hum... an engines failed. Better start that APU. Oh dear... the other main gen has failed... what an annoying coincidence. Good job we started the APU. except... bummer, thats failed as well. Now we're down to some scrawny Gen spinning off a hydraulic pump or something. And wouldn't you know... its failed as well, leaving us at battery power. Time to land ASAP etc etc..

But real failures aren't always as cooperative. In 25 years of flying, apart from the occaisional gen failing, the only time I've seen a really nasty electrical problem, the bit that failed was the core of the system.

The essential buses fell over, taking with them either directly, or indirectly (because those core buses supply the relays and indications for large chunks of the rest of the systems) pretty much everything on the aircraft.

I forget exactly what we were left with, but it wasn't much. The first officer's instruments were ok, and a couple of conventional navaids. But we had no hydraulics, no other flight instuments (both mine and the standbys were dead), no intercom, we had a radio each but both audio management panels were dead. Pretty much every other gauge or indicator in the flight deck was dead.

The only saving grace of the whole situation was - thank god, because it was a grobbly day and the F/O had hardly any time on type - we hadn't taken off yet. We got the tug to stick us back on stand and left it for the Engineers!

The situation we'd seen had not been covered in grounschool, the sim, and there wasn't even a checklist for it.

The point of this story? Electrical systems can fail from the inside outwards instead of the other way round. The fact that one of the main buses is still powered is no gauruntee that the really crucial stuff is healthy.

pb
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Old 5th Jun 2009, 04:30
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Two big questions!

1. Why, if ACARS was transmitting (AC power still available), there was no radio transmission on Guard?
It is a well established fact that there was at least 1 a/c (LH) within VHF range... The Germans (as opposed to pilots from some other nationalities) would definitely listen on Guard, especially in a remote area. In any emergency the PF (he takes over comms as per Airbus procedures) should make the "Mayday" call asap or if directed by ECAM (red LAND ASAP).
2. My company has some reasonably new Airbuses and even though they are not equipped with the manual ELT activation switch, I am 99% sure the AF a/c had this installed... Why didn't anybody manually activate the ELT? Monitoring stations around the World need only a few seconds of transmission to triangulate the position, and also the ELT might have (depending on model installed) transmitted it automatically... Can anybody enlighten us on the AF procedures regarding manual ELT activation from the cockpit? Please?
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Old 5th Jun 2009, 04:46
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The problem with either a MayDay or ELT activation is that they don't actually help right now while everything is going to Hell. They had their hands full (and then some, I suspect) doing the "Aviate" part of the response - "Communicate", especially where they were a long way from help, shouldn't have been anywhere on the priority list.
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