New hope for search results...
Autonomous Underwater Vehicles may soon find wreckage of Air France Flight 447
not sure if anyone has posted that link before; a quick scan of recent posts and I didn't see any reference to it

Mowing the Lawn
 

Mowing the lawn is an expensive and time consuming process, but what has to be done when you are not quite sure where the lost object has ended up. There was a sonar search for the SS America with towed sonar that took several months of sea time over a few years on a flat seabed

If they succeed in finding AF447 in a few weeks, it will be a sign the technology has greatly evolved.

After reading everything posted here, looking at what information is available at this time, coupled with 40 years of experience of flying;

I am in the 'slow news day non-event' group as well.

Update: "Seabed Worker" & "Anne Candies"
 

The following Radio Navigation Warning to Shipping has been issued by the Brazilian Navy:-

0048/10
NORTHWEST OF ARQUIPELAGO SAO PEDRO E SAO PAULO
CARTA 10(INT. 216)
VESSEL ANNE CANDIES - BLACK HULL AND WHITE SUPERSTRUCTURE AND
VESSEL SEABED WORKER - BLUE HULL AND WHITE SUPERSTRUCTURE
SEARCHED THE WREKAGE AR PERIOD: 01/APR TO 01/MAY
AREA INTERDICTED TO NAVIGATION AMONG PARALELS: 03-48.00N 03-00.00N AND MERIDIANS: 030-22.00W 031-09.00W
CAUTION ADVISED.
CANCEL THIS WARNING 020359 MAY 2010.
------------------
The area to be searched lies within -

3° 48'N 31° 09'W, 3° 48'N 30° 22'W
3° 00'N 31° 09'W, 3° 00'N 30° 22'W

The area covered by this warning is approximately 2,250NM^2, or 7,700km^2, centered on -
3° 24'N 30° 45.5'W.

The BEA have stated on a number of occasions that 2,000km^2 is the area to be searched, which equates to the area of a circle with a radius of 25.2km or 13.6NM.

mm43

mm43,
Using the back of an envelope, and after checking a few different announcements, it seems the search has been narrowed down to about 900 square miles (give or take a few), which is roughly a square of 30x30 miles, which would mean the actual impact point has been narrowed down to 3° 22'N 30° 45.5'W plus or minus 15 miles.

Statute or nautical miles? Not a huge difference anyway...

It still seems a pretty limited area, in view of all the incertainties about the debris field on the surface, and the local currents and winds at the time.
And 600 mph is 60 miles per minute, so again they think they've pinned down the time of impact to within a minute and a half?

It's only just the back of my envelope.... and yes, I truly wish them success, and luck... they'll probably need it!

CJ

ChristiaanJ,

Not disagreeing with your basic point, but my (mental) arithmetic makes the search area:

48 nm North-South X 47 nm (approx) East-West,

which is about 2250 nm²

From memory of flying the route, is the Upper Airway track aligned at about 015 deg(T)?

You're a bit adrift on timing. At a GS of (say) 480 kt, the (flight) time to transit the area would be about 6 minutes.

ChristiaanJ; Chris Scott;

Thanks for alerting me to the error - which has been corrected. I had looked at the warning area and deducted 5NM of each side to allow for a buffer zone, and that's how the original figures came about. http://images.ibsrv.net/ibsrv/res/sr...lies/wink2.gif

The airway track is 028°T, and the Last Known Position was 2° 58.8'N, 30° 35.4'W (3NM west of track), which gives 338.2°T x 27.1NM to 3° 24'N 30° 45.5'W.

Sure hope they get lucky.

mm43

mm43,

Thanks. I forgot to allow for a buffer zone, so search area seems to be more like 38nm X 37nm, and flight transit time on the airway track 028T of the order of 5 minutes.

I assume the BEA have good reason to believe that, unsurprisingly, the aircraft continued to deviate further to the left of the airway centreline?

Only an uneducated guess, but could it be the search area has been reduced because information has come from another source.

i.e. xx Navy submarines which may have picked up low frequency sound from some distance away and have calculated a bearing back to the source.

Chris Scott

The aircraft's Last Known Position appears to have been generated following a LOC incident which occurred with the onset of the various ACARS messages time-stamped initially at 0210z. The AOC position has priority and was injected into the stream at 02:10:30. No comment has been made by the BEA as to the actual timing of the AOC message, but it could be presumed that the ACARS time-stamp was not to the integer of the minute, but was rounded to the nearest minute - or the position was at 02:10:30z.
It is assumed that this deviation to the NNW had happened prior to the AOC position. The radius of the search area is a result of the difficulties presented when trying to backtrack debris drift allowing for current and leeway in a very fickle part of the ocean and at what was the effective center of the doldrums at the time of the accident.

The last satellite contact with the a/c was at 02:14:28 and the flight may have ended at that time or up to 45 secs later, as the BEA have determined that at least one ACARS FLT message remained to be transmitted.

mm43

Search Area and Drift Patterns
 

The following graphic is essentially the same that was posted to the AF447 thread in September 2009. Added to it are the boundaries of the Nav. Warning Area, and a shaded circular area representing the 2,000km^2 the BEA has said they have narrowed the search field down to. A small red triangle which indicates the original calculated backtrack for the V/S using OSCAR/NOAA satellite derived current data along with the QuikSCAT satellite derived 10m wind data, has also been added.

Somewhere back in the original post there is a comment regarding why I increased the current velocity by 50%, which seems now to have been wrong as the best data analysis available to the BEA has concluded it was actually around 50% less.

http://i846.photobucket.com/albums/a...ch-area-1a.png

A larger image is available at - http://i846.photobucket.com/albums/a...h-area-lge.png
mm43

Bank angle
 

I wonder what bank angle a pilot would typically use to change heading to avoid weather, while in cruise at M=0.8, FL350? I don't mean a late, impulsive action or emergency - you look at the radar, possibly discuss with the PNF, then decide to change heading 25 degrees left of track?
regards,
HN39

HN39,

Typically, as you suggest, it would be done in HDG mode, with the AP deciding the bank angle (unless you turned the HDG knob little-by-little). At that altitude, the bank angle would be nearer the 20 than the 35, I think. But perhaps a current A330 pilot will comment.

Chris

10 miles per minute, Christiaan

Rather unlikely
 

60 miles per minute equates to 3,600 miles per hour - would mean a quick trip but is quite unlikely

Chris Scott;
That's exactly how it's done and that's the bank angle achieved for the A330 when using HDG with autopilot ON.

More bank would have to be done manually but I've never seen a diversion done that way.

A bit more detail for those wishing it... A Rate One turn (3deg/sec) at a TAS of 450kts would be about 53deg bank. The maximum bank angle that will be maintained by the autoflight system (autopilot OFF) using the sidestick is 33deg; the maximum bank angle in Normal Law (autopilot OFF) with constant sidestick deflection is 67deg. Positive spiral stability is maintained by the autoflight sysem in Normal Law.

PJ2

mm - to save my digging back to September, can you remind me what the mauve '11-12' etc ponts are?

BOAC

The ORARO - TASIL track mauve numbers are the minute estimates at 463KTS GS based on previous AOC reports. There was a 10KT headwind forecast at FL350, so they represent about 473KTAS. The dots with the white spots in them in the off track deviation are purely speculative timings.

mm43

- yes, it was those to which I referred - whose 'speculation'?

Mine, in the course of trying to graphically represent a scenario where the a/c could have gone based on a backtracked position for the V/S.

mm43