Why is it so hard to find flight 447's black boxes?

BEA images
Debris scattered over quite a small area (600 m x 200 m) at 3900 m depth
which seem indicating that the plane impacted the ocean in one piece

From PhysicsCentral

The French government announced today that more bodies and wreckage from the Air France flight 447 crash off the coast of Brazil had been found almost two years after the crash.
The critical pieces of the puzzle, the plane's flight data recorders - or black boxes - are still missing, however.
But why are they so hard to find?

The wreckage from flight 447, which crashed in the Atlantic Ocean off the coast of Brazil in June 2009, is scattered over mountainous ocean floor at depths from 12,500 - 13,000 feet, or around 2.5 miles.
Though that doesn't sound very deep, especially when you consider that modern airliners often cruise at three times that height, it's far too deep for scuba divers or naval submarines to explore.

For every 33 feet you descend under water, the atmospheric pressure pushing down on you increases by 100 percent.
At the surface, every person and object has 14.7 pounds per square inch of air pressure pressing down on him or her.
That pressure feels normal to us, but once it is increased or decreased, it starts to cause problems.

Boyle's law tells us that as the pressure doubles, the volume decreases by half (assuming there's no change in temperature).
If, for example, we pulled a party balloon under water, at 33 feet - where the atmospheric pressure is doubled - the balloon would be half as big as it was at the surface.
Drag it down another 33 feet and it would shrink in half again.
Human's lungs are a lot like a balloon.
At around 100 feet, humans reach the limit of how much pressure their lungs can stand.

Imagine what it is like at 12,500 feet, where the wreckage is scattered.
Even modern naval submarines can't stand the pressure at that depth.
They call it a day at around 1,000 feet where the pressure is over 30 times the surface pressure. Beyond that, they could be crushed like an empty soda can.

Accident site (in the area of an abyssal plain) :
Note the position in the middle of the previous search zones on a flat and sandy seabed
around 5 NM, north of the last known position (LKP : 2°58.800 N, 30°35.400 W)
--> localization with the Marine GeoGarage <--

At the wreck site, the pressure is almost 400 times the pressure at the surface.
To survey the sea floor at 12,500 feet below the surface, a special mini submarine called a submersible is needed.
Submersibles have a limited range and can only stay under water for hours at a time so they usually work in conjunction with another vessel - a ship or a larger submarine.

A yellow submersible called Nautile, who previously surveyed the Titanic wreckage, helped originally locate flight 447 wreckage in 2009. (The Titanic wreckage is also at a depth of about 12,500 feet.) A similar sub, called Alvin, was also used to explore the Titanic wreckage when the ship was discovered.
Though it seems impossible, the tiny sub is protected by a titanium pressure hull just 2 inches thick. Both subs carry 3 explorers.

The sub that found the latest wreckage was an unmanned sub called a REMUS 6000.
The REMUS 6000, with no human occupants, can travel a little faster and a little longer than Nautile or Alvin, but even it can explore for only 22 hours at a time, limited by battery life.
(see BEA phase 4 mission preparation)

A deep, dark environment and the special tools needed to explore it make searching for anything at 2.5 miles under the sea a difficult task.
There's hope, after finding an engine and landing gear, that the black boxes may yet be found, and help solve the mystery of what really happened to flight 447.
Even if they are found, it's anyone's guess whether the boxes will have survived two years of crushing pressure in a corrosive seawater environment.

Links :

• BBC : Wreckage from Air France jet found in Atlantic
• NYT : Bodies from 2009 Air France crash are found
• TheGuardian : Air France plane crash victims found after two-year search
• CNN : Father of crash victims: Leave their remains under water
• BEA : Flight AF447, sea search operations, phase 4
• WHOI : WHOI-led team locates Air France wreckage
  

Canada CHS update in the Marine GeoGarage

1316 port de Québec

58 charts have been updated (CHS update, March 27)

• 1220 BAIE DES SEPT ILES
• 1311 SOREL-TRACY TO VARENNES
• 1312 LAC SAINT-PIERRE
• 1314 DONNACONA TO BATISCAN
• 1315 QUEBEC TO DONNACONA
• 1316 PORT DE QUEBEC
• 1317 SAULT-AU-COCHON TO QUEBEC
• 1430 LAC SAINT-LOUIS
• 1509A RIVIERE DES PRAIRIES/ ILE BIZARD TO PONT-VIAU
• 1509B RIVIERE DES PRAIRIES PONT-VIAU TO ILE BOURDON
• 3062 PITT RIVER AND PITT LAKE - PITT LAKE B-C
• 3441 HARO STRAIT BOUNDARY PASS AND SATELLITE CHANNEL
• 3442 NORTH PENDER ISLAND TO THETIS ISLAND
• 3463 STRAIT OF GEORGIA SOUTHERN PORTION
• 3477 BEDWELL HARBOUR TO GEORGESON PASSAGE
• 3490 (B-C) FRASER RIVER (SAND HEADS TO DOUGLAS ISLAND)
• 3492 ROBERTS BANK
• 3538 DESOLATION SOUND AND SUTIL CHANNEL
• 3539 DISCOVERY PASSAGE
• 3864 GOWGAIA BAY
• 4001 GULF OF MAINE TO STRAIT OF BELLE ISLE
• 4003 CAPE BRETON TO CAPE COD
• 4013 HALIFAX TO SYDNEY
• 4015 SYDNEY TO SAINT-PIERRE
• 4016 SAINT-PIERRE TO ST JOHN'S
• 4022 CABOT STRAIT AND APPROACHES
• 4023 NORTHUMBERLAND STRAIT
• 4024 CHALEUR BAY TO ILES DE LA MADELEINE
• 4047 ST PIERRE BANK BANC DE SAINT-PIERRE TO WHALE BANK
• 4118 ST. MARY'S BAY
• 4209 LOCKEPORT HARBOUR AND SHELBURNE HARBOUR (SHELBURNE HARBOUR)
• 4227 COUNTRY HARBOUR TO SHIP HARBOUR
• 4235 BARREN ISLAND TO TAYLORS HEAD
• 4241 LOCKEPORT TO CAPE SABLE
• 4243 TUSKET ISLANDS TO CAPE ST MARYS
• 4367 FLINT ISLAND TO CAPE SMOKEY
• 4374 RED POINT TO GUYON ISLAND
• 4381 MAHONE BAY
• 4405 PICTOU ISLAND TO TRYON SHOALS
• 4466 HILLSBOROUGH BAY
• 4474 ILES BUN TO BAIE DES MOUTONS
• 4483 CARIBOU HARBOUR
• 4486 CHALEUR BAY
• 4492 CASCUMPEQUE BAY
• 4498 PUGWASH HARBOUR AND APPROACHES
• 4624 LONG ISLAND TO ST. LAWRENCE HARBOURS
• 4625 BURIN PENINSULA TO SAINT-PIERRE
• 4641 PORT AUX BASQUES AND APPROACHES
• 4642 GREAT ST. LAWRENCE HARBOUR AND LAMALINE HARBOUR (LAMALINE HARBOUR)
• 4909 BUCTOUCHE HARBOUR
• 4913 CARAQUET HARBOUR BAIE DE SHIPPEGAN AND MISCOU HARBOUR
• 4920 CHALEUR BAY SOUTH SHORE
• 4921 HAVRE DE BEAUBASSIN
• 4950 ILES DE LA MADELEINE
• 4956 CAP-AUX-MEULES
• 4980 BLANC-SABLON
• 5056 KHIKKERTARSOAK NORTH ISLAND TO MORHARDT POINT
• 5059 SAGLEK BAY
• 6218A KENORA RAT PORTAGE BAY
• 6218B KENORA RAT PORTAGE BAY

So 692 charts (1647 including sub-charts) are available in the Canada CHS layer. (see coverage)

Note : don't forget to visit 'Notices to Mariners' published monthly and available from the Canadian Coast Guard both online or through a free hardcopy subscription service.
This essential publication provides the latest information on changes to the aids to navigation system, as well as updates from CHS regarding CHS charts and publications.
See also written Notices to Shipping and Navarea warnings : NOTSHIP

Dick and Peyron win the Barcelona World Race

From VendeeGlobe

Jean-Pierre Dick and Loïck Peyron have just won the second edition of the Barcelona World Race, the double-handed race around the world starting and ending in the Spanish port.
This win rewards an experienced, solid duo, whose combined skills enabled them to sail an exemplary race aboard Virbac-Paprec 3.
Unless they suffer some last minute damage, the Spaniards on Mapfre and Renault Z.E are likely to complete the podium in a race marked by the retiral of four crews that were expected to do well: Président, Foncia, Groupe Bel and Mirabaud.

We look back today at the key moments in these past three months of racing.

By winning the Barcelona World Race on Monday, Jean-Pierre Dick has achieved his second victory in this event, while Loïck Peyron adds another line to his remarkable list of achievements.
The magic certainly worked between these two experienced sailors, enabling them to dominate the race almost from start to finish, in spite of two pit stops in Recife and in Wellington.
But winning was no easy matter, as Jean-Pierre Dick stressed on the eve of this win by Virbac-Paprec 3 : “The competition was tougher this time (tougher than in the first edition three years ago, editor’s note) with a playmate to keep us company from the outset (Foncia). Then after New Zealand, we had to fight it out with MAPFRE right up to the finish. It was only when we were in the Indian Ocean that we really found ourselves alone.”

Duel at the front
Barcelona, 31st December 2010.
Fourteen duos crossed the starting line of the Barcelona World Race.
Very early on a duel developed between Virbac-Paprec 3 and Foncia, who were the first two boats to pass through the Straits of Gibraltar.
The start of the race was marked by the forced retiral of Jean Le Cam and Bruno Garcia, following on from the dismasting of their Président.
At the front, the duos of Dick/Peyron and Desjoyeaux/Gabart stuck with each other and both put into Recife in Brazil for a pit stop.
The battle continued until Foncia was dismasted in the South Atlantic a few miles from the Cape of Good Hope.
Michel Desjoyeaux and François Gabart were reluctantly forced out of the race.
Virbac-Paprec 3 began to tackle the southern ocean with a comfortable lead over the boats chasing after them, MAPFRE, Groupe Bel and Estrella Damm.
Jean-Pierre Dick and Loïck Peyron were all alone at the front in the Indian Ocean and were the first to cross the longitude of Cape Leeuwin.
But when they were forced to put into Wellington for a pit stop, the suspense built again.

MAPFRE manages to keep up, while Groupe Bel retires
The pit-stop lasted 48 hours and they set off again just 128 miles ahead of Iker Martinez and Xabi Fernandez, who achieved a remarkable recovery on board MAPFRE, the boat aboard which Michel Desjoyeaux won the last Vendée Globe.
Constantly on the attack, the Spaniards clawed back the miles and almost grabbed the lead.
Behind them, Estrella Damm and Groupe Bel carried out a pit stop in Wellington.
This situation benefited Pachi Rivero and Pepe Ribes, who took third place aboard Renault Z.E.
Still at the front, Jean-Pierre Dick and Loïck Peyron extended their lead as they approached Cape Horn, and went on to round it with a good lead.
On board Groupe Bel, Kito de Pavant and Sébastien Audigane rounded the Horn too, but were forced to retire with a damaged keel. Kito de Pavant would not complete his first round the world voyage.
“This was a difficult decision, as we have completed the hard part of this Barcelona World Race, “ he explained, before adding, “It is of course very frustrating, as we just had the Atlantic left and we had hoped to continue the fight to earn our place on the podium.”

Dick-Peyron a winning duo

Dick and Peyron in control
A few days later, Mirabaud was dismasted after rounding Cape Horn.
The adventure was over for Dominique Wavre and Michèle Paret, after their third place in the first edition of the race.
At the same time, Dick and Peyron were continuing their climb up the Atlantic.
But stuck in the Doldrums that were particularly active, they saw their lead over Iker Martinez and Xabi Fernandez melt away as they were slowed down much less in the intertropical convergence zone.
But the French were to recover and extend their lead again.
The two crews went into stealth mode as they rounded the Azores high, but this little trick was not to change anything on the ground. Virbac-Paprec 3 could be confident of winning the race unless they suffered some damage.
With strong headwinds and boat-breaking seas, the end of the race was particularly tough on the leaders. As they passed Gibraltar, the boat experienced the worst conditions since the start of the race. After this violent episode, they were to find themselves becalmed.
The Mediterranean certainly lived up to its reputation.
Virbac-Paprec 3 went on to cross the finishing line at 10h20 GMT on Monday, after 93 days 22 hours and 20 minutes of racing.

Second place
Unless there is a major upset, MAPFRE is set to take second place today.
A fine result for this crew, who managed to make up for their lack of experience by showing faultless determination.
Renault Z.E will almost certainly take third place, thus confirming the overall improvements in Spanish sailing.
Thanks to some good strategic choices, Pachi Rivero and Pepe Ribes managed to ward of the repeated attacks of Estrella Damm and Neutrogena, respectively in fourth and fifth place on Monday.
After Central Lechera Asturiana was forced to turn back and head for New Zealand this Monday morning, four other duos are continuing towards Barcelona: GAES Centros Auditivos, Hugo Boss, Forum Maritim Catala and We Are Water.
They have all had their own problems. Only Dee Caffari and Anna Corbella, aboard GAES Centros Auditivos, have not carried out a pit stop.
With large gaps between them, these crews now only have one real ambition and that is to complete their round the world voyage.

Links :

• TheDailySail : Well earned victory
• YachtPals : Barcelona World Race winners
• Marine GeoGarage blog : Barcelona WR, second edition for the two-handed world race

Deep-sea volcanoes don’t just produce lava flows, they also explode!

Underwater volcanic eruptions and magma flows on the sea floor have been seen
for the first time ever thanks to video captured by NOAA

From McGill University

McGill geology researchers’ discovery of high concentrations of CO2 at mid-ocean ridges confirms explosive nature of certain volcanic eruptions

Between 75 and 80 per cent of all volcanic activity on Earth takes place at deep-sea, mid-ocean ridges.
Most of these volcanoes produce effusive lava flows rather than explosive eruptions, both because the levels of magmatic gas (which fuel the explosions and are made up of a variety of components, including, most importantly CO2) tend to be low, and because the volcanoes are under a lot of pressure from the surrounding water.

Over about the last 10 years however, geologists have nevertheless speculated, based on the presence of volcanic ash in certain sites, that explosive eruptions can also occur in deep-sea volcanoes.

But no one has been able to prove it until now.

By using an ion microprobe, Christoph Helo, a PhD student in McGill’s Department of Earth and Planetary Sciences, has now discovered very high concentrations of CO2 in droplets of magma trapped within crystals recovered from volcanic ash deposits on Axial Volcano on the Juan de Fuca Ridge, off the coast of Oregon.

These entrapped droplets represent the state of the magma prior to eruption.
As a result, Helo and fellow researchers from McGill, the Monterey Bay Aquarium Research Institute, and the Woods Hole Oceanographic Institution, have been able to prove that explosive eruptions can indeed occur in deep-sea volcanoes.
Their work also shows that the release of CO2 from the deeper mantle to the Earth’s atmosphere, at least in certain parts of mid-ocean ridges, is much higher than had previously been imagined.

Given that mid-ocean ridges constitute the largest volcanic system on Earth, this discovery has important implications for the global carbon cycle which have yet to be explored.

Links :

• Nature : Explosive eruptions at mid-ocean ridges driven by CO2-rich magmas
• NOAA : Scientists discover and image explosive deep-ocean volcano (video)
  
• YouTube : Undersea volcano eruption 2009 (Tonga )
  

Fat Irish barrels at Mullaghmore Head

Shambles "A day in the life" from Peter Martin

Mullaghmore Head 05/10/2010 from Peter Martin

Mullaghmore Head "Tow in Surf Session" from Mully Productions

-> localization with the Marine GeoGarage