franceinsummer

BEA has posted on its website:

Press release 20 August 2009 Flight AF 447 on 1st June 2009 A 330 – 200, registered F-GZCP

The second phase of the undersea search operations for the flight recorders from the Airbus A 330 that disappeared on 1st June 2009 has just been completed. The Pourquoi pas? is expected at Dakar today.

The work, undertaken with the assistance of IFREMER and SHOM, allowed completion of the exploration of the search area that had been defined after the accident, a circle with a radius of 75 km centred on the last position message transmitted by the airplane at 2h10. Bathymetry of the ocean floor was also performed over a wider perimeter.

As the searches did not make it possible to locate the airplane wreckage, the BEA will gather together a team of international investigators in the next few weeks to analyze the data collected with a view to a third search phase and to determine the requirements and means to undertake this.

SEE UPDATE

Air France Flight 447: Unsuccessful Searches And Pitot Maintenance (UPDATED) Black Boxes Located?


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Flight 447 black boxes ‘not found’

theage.com.au – August 21, 2009 – 5:49AM

French investigators say they have abandoned a second round of search efforts for the black box flight recorders from Air France Flight 447, believed to be resting in the depths of the Atlantic. The Airbus jet crashed into the ocean June 1 en route from Rio de Janeiro to Paris, killing all 228 people aboard.

The flight’s voice and data recorders could provide important clues as to what precipitated the accident, whose cause has so far stumped investigators. The French accident investigation agency, known as the BEA, said in a statement that the research ship leading the hunt for the plane’s flight recorders had left the site, more than 1,400 kilometres off Brazil’s northeastern coast. The ship, the Pourquoi Pas, was to arrive in Dakar, Senegal, on Thursday.

The statement said the second phase of search efforts, focusing on the underwater hunt for debris and the black boxes, “has finished”. Investigators and experts will gather in the coming weeks to determine whether to launch a third phase. “We have not found the wreckage, we have not found the recorders,” BEA spokeswoman Martine del Bono said.

She said the BEA would gather a team of about 10 specialists from several countries including Brazil, France, the United States and Germany, to study the data gathered from the second phase and decide what a third search phase would cost and require. She gave no estimate on when an eventual third mission might begin. The investigation “is far from finished,” she said. “We must find” the black boxes, she added.

During the first phase of the search, rescuers recovered 50 bodies and more than 600 pieces of the plane scattered on the sea. The second phase of the search began after the black boxes stopped emitting signals, about a month after the crash. Airbus promised to help fund a third phase of the search over a wider area if necessary.

A preliminary report into the crash said the plane hit the ocean intact and belly first at a high rate of speed. But without the flight recorders, investigators may never fully understand what happened. Investigators have said there were no signs of explosion or terrorism.


debriscurrentstraj


Response to Airbus Pitot Tube Incidents Under Scrutiny

Aviation Week and Space Technology

By Jens Flottau

Is Europe’s aviation safety system proactive enough to head off safety concerns? That has become a question in the wake of how regulators and other stakeholders have dealt with problems linked to Thales pitot tubes on Airbus aircraft…

… French accident investigators insist they have no evidence to lead them to conclude the pitot tubes were responsible in any way for the crash, a point Air France CEO Pierre-Henri Gourgeon has also emphasized.

Another big unknown is whether pilot performance may have been a factor; flight crew workload increases while navigating near severe weather. Since the crash of Flight 447, EASA and Airbus have reminded operators of the need to ensure that pilots are skilled in techniques to maintain level flight.

Air France underwent an extensive review of its safety operations following the 2005 crash landing of an A340 in Toronto. The report was highly critical of its safety and pilot training standards. Executive Vice President of Operations Gilbert Robetto says 90% of the recommendations have been implemented.

But four of Air France’s pilot unions recently demanded further changes, including more simulator time… Thales did not respond to Aviation Week’s questions. Airbus would not comment, citing the ongoing investigation of Flight 447.

EASA stopped short of banning the Thales probes outright, allowing operators to continue to use the so-called -BA standard as a third sensor on Airbus widebodies. A regulatory official says continued use of one Thales -BA probe is “probably acceptable.”

Despite the higher propensity for icing, EASA officials have also allowed the -BA probes to continue to be used on A320s. An agency official says tests indicate that most failures occurred at Flight Level 35 (35,000 ft.) or higher and temperatures of -50C or lower. These results could be a hint that extreme weather conditions could have played a role in the Flight 447 crash, he adds. The aircraft had almost traversed an area of severe weather in the intertropical convergence zone when the ACARS failure message regarding unreliable airspeed data was sent.

What is raising eyebrows is that EASA and Air France officials say they tried to get clarification from Airbus as to how to handle problems with the probes long before the Flight 447 crash. An overview of the past 18 months also indicates that operators have been expressing concern about the issues with Airbus for at least this period.

… In a June 8 service bulletin, Airbus reiterated that both of Thales’s -AA and -BA and the Goodrich P/N 0851HL could still be operated.

That assessment came in spite of one incident on May 21: A TAM A330-200 temporarily lost all speed indications on a Miami-Sao Paolo flight. In a June 23 event, a Northwest A330 en route from Hong Kong to Tokyo experienced a temporary failure of speed and altitude indicators. Both inflight upsets could potentially be linked to pitot probe icing, although the U.S. National Transportation Bureau investigations are ongoing.

At that point, Airbus again changed its view on the issue by issuing a safety telex to operators on July 30. The telex stated that “dedicated wind-tunnel tests will be conducted under conditions more severe than currently applicable certification requirements to consolidate the knowledge of the behavior of each type of probe under extreme conditions.”

Airbus recommends installing Goodrich-built probes into the No. 1 and 3 positions (Captain and standby) (see photo, p. 24) while the probe serving the first officer’s instruments can remain Thales-equipped. The recommendation “is not applicable to A320-family aircraft at this stage.”

Following the 2008 incidents, EASA claims to have asked Airbus for more details about how the manufacturer planned to deal with the problem – but long after dangers of pitot probe icing were known to its own experts. The effort came after Air France saw increased probe failure rates and Air Caraibes suffered its inflight problem. That is also when the agency said it asked the manufacturer to come up with proposals about how the probe reliability issues could be resolved.

Airbus, meanwhile, plans to review recurrent pilot training programs for unreliable airspeed conditions and hands-on flying, particularly at high altitude. Also, the manufacturer “will encourage at industry level the review of applicable certification requirements for icing conditions.”


klm_phaob02

Rectification – KLM Grounding A330 Fleet

Worldwide Aviation Net

Rectification following an article earlier today with regard to KLM suspectingly grounding its A330 fleet. Confirmed sources around the airline have told Worldwide-Aviation.net that all Airbus A330 in service of KLM are still in operation. Replacement of the pitot probes is an ongoing process and it is not expected that this would form a problem maintaining the current flight schedule.

Replacement of the pitot probes follows after an Airworthiness Directive (AD) publication by EASA stating that the currently installed probes from Thales should be replaced by those produced by Goodrich (at least two of three used on the A330). In response KLM has announced installation of the new tubes will be accomplished as soon as possible. In addition, KLM states that installation of the new probes is a preventative measure and that safety has never been, and will be, compromised in any way.


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Aero-Instruments to offer pitot tubes for Airbus aircraft

Flightglobal – By John Croft
Ohio-based Aero-Instruments has received US FAA parts manufacturer approval (PMA) to market retrofit pitot probes for a large variety of Airbus aircraft, giving operators another provider to choose from along with Thales and Goodrich for the devices.

Interest in pitot tubes is reaching a zenith as European safety regulators have decided to require Airbus A330 and A340 operators to replace their Thales pitot probes in the wake of the Air France A330-200 accident over the South Atlantic on 1 June. Based on automated maintenance data transmissions sent before the crash, investigators have determined that the aircraft’s velocity measurements were in error, perhaps due to icing.

The Aero-Instruments probes are approved as direct replacements on more than 4,500 Airbus aircraft, including the A320 family as well as the A330 and A340 series aircraft. Airbus uses Goodrich probes on factory built aircraft, and says that 80% of the 1,000 A330 and A340 aircraft delivered aircraft continue to use Goodrich probes. Thales pitot tubes are sold as an option.

An EASA directive expected to be issued in the coming weeks will require operators to change out at least two of the three Thales probes on each aircraft, though officials at Airbus say the devices meet certification standards as written. Pitot tubes measure the pressure of the incoming ram airstream and compare the reading to static (non-moving) air pressure measured elsewhere to derive airspeed. Airbus uses readings from three pitot tubes on the aircraft’s nose to derive airspeed. The devices include a heating element that prevents the tube from freezing closed when moisture is present.

Aero-Instruments, which has been developing the PMA pitot probe for the past 18 months, is best known for its Embraer and Bombardier regional aircraft pitot tubes as well as its general aviation line. The company produces about 15,000 pitot tubes per year, says Ryan Mifsud, Aero-Instruments vice president and general manager.

Mifsud says it does not yet have an Airbus customer for the PMA pitot tubes, but the PMA will “open the door” for discussions.


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Probe Finds Airspeed Sensors Failed on at Least 12 U.S. Flights

Fox News (via AP), Friday, August 07, 2009

On at least a dozen recent flights by U.S. jetliners, malfunctioning equipment made it impossible for pilots to know how fast they were flying, federal investigators have discovered. A similar breakdown is believed to have played a role in the Air France crash into the Atlantic that killed all 228 people aboard in June.

The discovery suggests the equipment problems are more widespread than previously believed. And it gives new urgency to airlines already scrambling to replace air sensors and figure out how the errors went undetected despite safety systems.

The equipment failures, all involving Northwest Airlines Airbus A330s, were brief and were noticed only after safety officials began investigating the Air France crash — on a Rio de Janeiro to Paris flight — and two other recent in-flight malfunctions. The failures were described by people familiar with the investigation who spoke only on condition of anonymity because they were not authorized to comment publicly.

While a car’s speedometer uses tire rotation to calculate speed, an airplane relies on sensors known as Pitot tubes to measure changing air pressure. Computers interpret that information as speed. And while a car with a broken speedometer might be little more than an inconvenience, many airplane control systems rely on accurate speed information to work properly.

Like the fatal Air France flight, the newly discovered Northwest incidents and the two other malfunctions under investigation all involved planes with sensors made by the European electronics giant Thales Corp. The Air France crash called into question the reliability of the sensors and touched off a rush to replace them.

Many companies, however, simply replaced them with another Thales model. As it became clear the problem was more widespread, Airbus and European regulators told companies to replace at least two of the three sensors on each plane with models made by North Carolina-based Goodrich Corp. The planes are allowed to continue flying while the switch is made.

Thales officials declined to comment. The company has previously said its sensors were made to Airbus specifications. The Northwest incidents were discovered when Delta Air Lines, which merged with Northwest last year, reviewed archived flight data for its fleet of 32 Airbus A330s, the people close to the inquiry said. All the planes involved landed safely.

Aviation experts said the discovery could provide clues to what caused Air France Flight 447 to crash into the Atlantic en route from Brazil to France on June 1, and what might be done to prevent future tragedies. French investigators have focused on the possibility that Flight 447’s sensors iced over and sent false speed information to the computers as the plane ran into a thunderstorm at about 35,000 feet.

An important part of the investigation focuses on 24 automatic messages the plane sent during its final minutes. They show the autopilot was not working, but it is unclear whether the pilots shut it off or whether it shut down because of the conflicting airspeed readings. Three weeks after the Air France crash, the U.S. National Transportation Safety Board announced it was investigating two other A330 flights that experienced a loss of airspeed data.

The most recent was on June 23, when a Northwest flight hit rain and turbulence while on autopilot outside of Kagoshima, Japan. According to an NTSB report, speed data began to fluctuate. The plane alerted pilots it was going too fast. Autopilot and other systems began shutting down, putting nearly all the plane’s control in the hands of the pilot, something that usually happens only in emergencies.

In May, a plane belonging to Brazilian company TAM Airlines lost airspeed and altitude data while flying from Miami to Sao Paulo, Brazil. Autopilot and automatic power also shut down and the pilot took over, according to an NTSB report. The computer systems came back about five minutes later.

“These two cases we know were dealt with effectively by the crew, and we think this happened in Air France and maybe wasn’t dealt with effectively,” said Bill Voss, president of the Flight Safety Foundation in Alexandria, Va., an aviation safety think tank.

Morgan Durrant, a spokesman for the only other U.S. airline that operates A330s, US Airways, said it had not seen similar problems in its 11-plane fleet of the jetliners. Delta/Northwest and US Airways recently completed replacing older Thales tubes with new Thales tubes. The companies say they are now replacing them with Goodrich tubes.

In June, the Air France pilots’ unions urged its members to refuse to fly Airbus A330s and A340s unless their Thales sensors had been replaced. The Federal Aviation Administration hasn’t issued a safety directive, but spokeswoman Laura Brown said the agency hopes to have one soon.


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ON-LINE AVIATION CHATTER /

MSG BOARDS / DISCUSSIONS

Below are on-line aviation chatter and message board discussions which I found to be interesting.  Please understand the below are only chatter/discussions among aviation professionals world-wide and should not be considered fact until all official information is released by BEA.

****Contains Speculative Analysis****

PPRuNe Forums Poster/Comments:

Careful examination of the OSCAR/NOAA surface current data provides 065°T x 22.5cm/sec at 3°N 31°W over the 5 day period centered on 2 June 2009.

I have therefore examined the positions in which bodies were recovered from on 6/7/8 June and constructed a likely current line based on what we know, i.e. that for the 3 days just mentioned and a calculated rate for the 5 – 6 June of 19cm/sec (9NM/day) back to the time of the accident at about 02:14:30Z on 1 June of 22.5cm/sec (10.5NM/day).

The reason for using the bodies as a check on the current is that they will have initially sunk to a point of equilibruim, and provided the depth was not too great, the water temperature would have commenced the decomposition process.

Then over a period of time each of these bodies would have gained enough buoyancy to become visible on or near the surface – which explains the number of days it took to find those that they did.

The point is that the bodies will have been subject to little or no leeway effects due to the surface wind. SHOM data shows that large easterly vectors on the surface become small westerly vectors the deeper you go, which helps to explain why some debris items floating with possibly little or no windage have been found to the east of the general drift line in which the bodies were found.

The graphic below shows 2 significant cumulonimbus cells, the one on the track and another left of the track shortly after passing ORARO. It seems that each of these mesoscale cells has played a part in this incident.

af447-lkp-lge-3b

I surmise that for some unknown reason the WX radar has not revealed the presence of the cell the a/c penetrated at around 0209, but when everything turned pear shape at 0210 the PF made a decision to get out of the ITCZ and commenced a lefthand 180 and descent hand flying the a/c with somewhat degraded control systems provided in Alternate/Direct law.

The lefthand turn was unfortunately taking the a/c toward the Cb cell NNW of ORARO.

What happened during the SATCOM outage between 0213 and 0214 is of course speculative, but at some point in this rapid descent it can be assumed that IAS became available and an effort was made to stabilize the rate of descent. If a nose up attitude was adopted, the updraft associated with the next Cb cell may have resulted in a flameout of both engines.

Well the graphic shows the general idea, but if the current vector at 3°N 31°W was in fact 055°T x 20cm/sec, the impact point would have been about 10NM further east. This would give better GS but with a tighter turn – to be expected if the speedbrakes were deployed.


Thank you for this nice work.

I visualize the final trajectory in a very similar way than yours, two aspects expected maybe:

– this large route deviation would be unvoluntary, this would be the horizontal trace (large roll perturbation) of the high altitude cruise loss of control, this would occur as a consequence of a large exceedance of the MMO (Mach>0.89-0.90) and this severe overspeed would require ~1mn or over to occur [*]: the tight turn would start around ~02:11:00Z

– this turn would not be a constant load factor turn (a part of a circle) with such a high constant curvature radius but a trajectory where the shortest radius (highest load factor, highest roll) is at the beginning of the initial route departure and where it decreases (roll is being controlled) in less than one minute.

This tight turn would probably go with a rapid loss of lift/altitude ? Once the roll is back under control, the pilots were in position to try to regain control in the vertical plane ?

(AoA/incidence, pich). This would be the final part of the trajectory: rather linear in the horizontal plane and in the vertical plane, a rapid loss of altitude (~10 000 fpm), the AoA/incidence decreasing in a first time to regain the aerodynamical authority (also with the loss of altitude and the increasing air density – stall recovery) and increasing again to generate enought vertical Gs to try to break the catastrophic descent.

The plane being “en ligne de vol” (straight horizontal trajectory / wings leveled, small horizontal speed component / speed mostly vertical, possibly a slight nose up)

finalhorizontaltrajecto

Indeed the drifting of the bodies or of the debris can be very different if you look where was recovered the left wing spoiler (this latter, recovered north of TASIL, seems like an outlier in the debris distribution, it has not been much deviated westward by the westernly surface winds derived from the satellite scatterometers, see windscat).

I will have another look to the surface current values over the first days of June since I have used values slightly lower than yours (and much lower than the SHOM values). I am studying the slopes distribution of the seabed in the area where the debris should have been colocated the 1st of June at 02:15Z.

I wish to validate my computations before I produce any graph results (missing values in the numerical terrain model) but it appear that between 5% and 10% of the seabed slopes are between 25° and 50°, using a 1.25km square bin resolution (narroy faults, slope details finer than this 1.25 km are lost/not observable). This bathymetry must be a real pain: towing up and down the multibeam sounder with the relief, varying scanning speed/resolution as a function of the slope, etc… Would it be a luxury to send another high resolution sounder to probe this area ?


The spoiler you referred to was I think the starboard outer which was picked up by a merchant ship north of TASIL on 13 July. If it had detached on account of an overspeed event, then that would help to explain its recovered position not falling within the range of expectation provided by the surface current/wind data.

This would also fit in with the high Gs roll/bank to port and the high speed descent toward the suspected crash site as postulated by you in a recent post.

af447-quikscat-1

I have extracted the Quikscat mean surface (+10m) winds from the NOAA site and determined that the mean surface wind at 3°N 30°W for the period 1 – 7 June was from 079.3°T x 11.06 knots (5.69m/sec). The vertical stabilizer has a very low profile to windage, in fact the only significant airfoil was the small piece of empennage skin rolled up and inward on the forward end.

The leeway for the v/s shown on the graphic below was 221°T x 11.1NM with reference to the general position of the 5 bodies recovered on 7 June. Without knowing the precise timings for either position (which could have been any time between sunrise and sunset) there is some room for positional error.


af447-lkp-lge-3

The effective windage factor calculated from the graphic is 0.74% which doesn’t seem unreasonable. Applying the same factor to the Quikscat data provides a leeway of 259.3°T x 12.8NM over 6.5 days. Sun shadow on a photo taken at the time of the v/s recovery indicates that the sun was near or on the meridian, i.e. 1400z.

However, when comparing the Quikscat data with the MSL analysis during the period in question, the wind vector should be more northerly. Putting that aside, the calculated result puts the v/s where it should be +/- a couple of miles.



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