Posted on 03/24/2014 10:34:25 AM PDT by don-o
snip
"We looked at the Doppler effect, which is the change in frequency, due to the movement of a satellite in its orbit. What that then gave us was a predicted path for the northerly route and a predicted path the southerly route," explained Chris McLaughlin, senior vice president of external affairs at Inmarsat.
This information was relayed to Malaysian officials by 12 March, but Malaysia's government did not publicly acknowledge it until 15 March, according to the Wall Street Journal. Malaysia began to redirect the search effort that day, to focus on the areas the information described. However, some officials involved with the probe warned that the lost days and wasted resources could impede the investigation.
Meanwhile, Inmarsat's engineers carried out further analysis of the pings and came up with a much more detailed Doppler effect model for the northern and southern paths. By comparing these models with the trajectory of other aircraft on similar routes, they were able to establish an "extraordinary matching" between Inmarsat's predicted path to the south and the readings from other planes on that route.
"By yesterday they were able to definitively say that the plane had undoubtedly taken the southern route," said McLaughlin.
These pings from the satellite – along with assumptions about the plane’s speed – helped Australia and the US National Transportation Safety Board to narrow down the search area to just 3 per cent of the southern corridor on 18 March.
(Excerpt) Read more at telegraph.co.uk ...
Depends on lots of things at that point.
When the main engines fail, there’s an APU (aux. power unit) that’s a little turbine/genset that is supposed to start to maintain electrical and hydraulic power for the flight control systems. Eventually, that’s going to run out of fuel as well.
In the Boeing heavies, then a RAT (Ram Air Turbine) drops out of the underside of the jet to provide emergency electrical and hydraulic power for the control systems and surfaces. Even with no fuel, the plane’s engineers planned for allowing control of these “fly by wire” systems.
The problem is that the optimum glide speed is “moving right along” in these heavy jets. We’re talking over 200 knots - perhaps as high as 240 knots airspeed. Their glide ratios are over 15:1 (typically) and they’re losing altitude at a pretty good clip (3000 to over 4500 feet per minute) to maintain an optimum glide speed and flight profile.
This ain’t like losing the engine in a Cessna 172 and gliding it down to the airstrip, flaring in the ground effect and kicking in a little crosswind rudder to line ‘er up on the runway. Pilots can and have glided Boeing heavies into a successful landing on even improvised airstrips - so Boeing heavies do glide successfully. In this case, however, we don’t know if there was a pilot at the controls, or a pilot who wanted to live, or what. All I meant with the above comment is that if the 777 went into the sea at a high speed and high angle, the debris field is likely to be quite limited. Look at what happened to the hijacked Flight 93 that was deliberately flown into the ground at a high angle in PA - there was actually little surface disturbance and a very small amount of debris above ground:
http://www.slimyfish.net/images/blog/flight93.jpg
There’s an additional proviso here too: They had help from the ground.
One thing that really needs to be answered is “was there an on-board fire in the cargo hold?”
That could explain quite a few things we’re seeing here.
Interesting, thanks.
Just had a thought while outside picking up some glass from small greenhouse that was suppose to be shatterproof
I know the glass in the cockpit is very strong. What would it take to break it?
Dunno.
Lots of things come into play again.
Do you know if one has ever broken in flight?
They do have very small peroxide thrusters on them to make small corrections as they are needed to maintain its relative position. I know a guy who makes them.
Wow that picture is amazing, never realized it had such a small impact zone. Presumably there would be more of the aircraft left hitting water than dry land, especially in a part of the ocean where there is usually a turbulent swell.
I could be out of bounds, but as far as I know they are made of Lexan (polycarbonate) and they are very strong. Bullet proof or resistant windows are of the same material. We use lexan in race cars for all the windows where the rules allow. Most things either bounce off, leave a mark and if big enough will crack it.
If a window is cracked could it just pop out? Ever have a car loose a window?
True, but the theory is looking better now. Doppler is a tried and true technique for locating radio beacons. Testing the theory with known flown routes is also a solid method.
A friend of mine had an engine starter hit his windshield made of Lexan and it cracked but it did not cave in like safety glass will. The only other windows I’ve seen come out is when the car got into an accident and turned around filling the cockpit with pressurized air and it bent the hold-down clips holding it in place.
I also will be 10-10 on the side. I’m waiting for the next shoe to drop.
Referring to the 777, assuming it's on autopilot and no pilot input, when fuel runs out and it starts to descend, the AP will disengage, and the aircraft will continue to glide in the trim attitude the AP had used. The normal glide ratio of a large swept wing transport is in the 20 to 1 range. So, if it was at 35,000 (about 7 miles up) it would glide 140 miles at most.
An onboard fire large enough to disable aircraft systems will quickly weaken the airframe enough to cause a breakup, within minutes, not hours.
Doubt it.
I think a cargo hold fire sufficient to kill the pilots would have destroyed the aircraft.
But (need help from knowledgeable FReepers here) there is an avionics bay under the cockpit which is accessed by a hatch behind the cockpit door. I don’t know if that bay has a fire suppression system. Suppose a slow fire started there, slow enough to kill the systems one by one. Suppose also that the fire generated enough CO to kill the pilots before it burned out. CO intoxication is very sneaky, it’s not like smoke inflation or toxic fumes.
With the cockpit door secured, and two dead pilots, could a 777 fly that long?
That is certainly understandable. For me, I hear things from one source that do not exactly agree with what I hear from another. It's the nature of how news is now reported. Nothing to be done about it except sharpen ones own analytical skill, look at the totality and draw reasonable conclusions.
Um, they're still in orbit aren't they? I mean, they don't just hover there in the same place.
But then, what do I know? Maybe, they do.
Just some positive PR for Inmarsat (not that they don't deserve it) together with an appeal for government mandating of better tracking.
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