After French authorities retrieved the MH370 flaperon from Réunion Island, they flew it to the Toulouse facility of the DGA, or Direction générale de l’Armement, France’s weapons development and procurement agency. Here the marine life growing on it was examined and identifed as Lepas anatifera striata, creatures which have evolved to live below the waterline on pieces of debris floating in the open ocean.
Subsequently, flotation tests were conducted at the DGA’s Hydrodynamic Engineering test center in Toulouse. The results are referenced in a document that I have obtained which was prepared for judicial authorities by Météo France, the government meteorological agency, which had been asked to conduct a reverse-drift analysis in an attempt to determine where the flaperon most likely entered the water. This report was not officially released to the public, as it is part of a criminal terrorism case. It is available in French here.
Pierre Daniel, the author of the Météo France study, notes that the degree to which a floating object sticks up into the air is crucial for modeling how it will drift because the more it protrudes, the more it will be affected by winds:
This translates as:
The buoyancy of the piece such as it was discovered is rather important. The studies by the DGA Hydrodynamic Engineering show that under the action of a constant wind, following the initial situation, the piece seems able to drift in two positions: with the trailing edge or the leading edge facing the wind. The drift angle has the value of 18 degrees or 32 degrees toward the left, with the speed of the drift equal to 3.29% or 2.76% of the speed of the wind, respectively.
The presence of barnacles of the genus Lepas on the two sides of the flaperon suggest a different waterline, with the piece being totally submerged. In this case we derive a speed equaly to zero percent of the wind. The object floats solely with the surface current.
This suggests a remarkable state of affairs.
Inspection of the flaperon by Poupin revealed that the entire surface was covered in Lepas, so the piece must have floated totally submerged—“entre deux eaux,” as Le Monde journalist Florence de Changy reported at the time. Yet when DGA hydrodynamicists put the flaperon in the water, it floated quite high in the water, enough so that when they blasted it with air it sailed along at a considerable fraction of the wind speed.
As point of reference, Australia’s CSIRO calculates that that the drifter buoys that it uses to gather ocean-current data pick up a 1.5% contribution from the wind. Here is a picture of one such drifter, kindly supplied to me by Brock McEwen. You can see that more than half of the spherical buoy is out of the water.
It is physically impossible for Lepas to survive when perched up high in the air. Yet the buoyancy tests were unequivocal. So Daniel pressed on, conducting his analysis along two parallel tracks, one which assumed that the piece floated high, and the other in which it floated submerged. For good measure, he also considered scenarios in which the flaperon floated submerged until it arrived in the vicinity of Réunion, and then floated high in the water for the last two days. (Note that he doesn’t present any mechanism by which a thing could occur; I can’t imagine one.)
After running hundreds of thousands of simulated drift trials under varying assumptions, Daniel concluded that if the piece floated as its Lepas population suggests, that is to say submerged, then it couldn’t have started anywhere near the current seabed search area. (See chart above.) Its most likely point of origin would have been close to the equator, near Indonesia. His findings in this regard closely mirror those of Brock McEwen and the GEOMAR researchers which I discussed in my previous post.
Daniel found that when simulated flaperons were asssumed to have been pushed by the wind, their location on March 8, 2014 lay generally along a lone that stretched from the southwest corner of Australia to a point south of Cape Horn in Africa (see below). This intersects with the 7th arc. However, as Brock has pointed out, such a scenario should also result in aircraft debris being washed ashore on the beaches of Western Australia, and none has been found. And, again, the presence of Lepas all over the flaperon indicates that such a wind contribution could not have been possible.
Pierre Daniel’s reverse-drift analysis for Météo France, therefore, presents us with yet another block in the growing stack of evidence against the validity of the current ATSB search area in the southern Indian Ocean.
The most important takeaway from this report for me, however, is the stunning discrepancy between how the flaperon floated in the DGA test tank and the “entre deux eaux” neutral buoyancy suggested by its population of Lepas. No doubt some will suggest that the flaperon may have contained leaky cells that slowly filled as it floated across the ocean, then drained after it became beached. However, I find it hard to believe that an organization as sophisticated as the DGA would have overlooked this eventuality when conducting their wind tests. Rather, I read Daniel’s report as evidence that the French authorities have been unable to make sense its own findings. I suspect that this is the reason that they continue to suppress them up to this day.
@Middleton.
Thanks for your answer and suggestion.
First the ‘start-altitude’ at 19:41 of 35Kft and ending at 15Kft around 29S 98E where fictional altitudes mentioned in the example VictorI and Oleksandr discussed (as I understood it well).
As was the fixed descent-rate at -0.1 that would lead to this altitude of 15Kft on 29S.
I took- and take it for fact from these (in my eyes) obvious experts that such an auto pilot mode is possible. You disagree? Why?
I realy like to know.
I don’t quite understand why you come up with 22Kft starting hight where I mentioned a fictional 35Kft starting hight at 19:41.
I guess you could choose any reasonable/possible starting hight?
The question you state about the problem with a curving path without a magnetic bearing on the first waypoint to meet the rings, instead of a fixed final waypoint and how you can get the aircraft to do that(?), is a question I realy like to hear an answer to.
I don’t know. I think sure Oleksandr or VictorI could answer that question?
About knowing when to reach fuel exhaustion.
I guess a pilot knows his amount of fuel and the max distance he can reach with it? Besides it’s not neseccary to fly until fuel exhaustion if you asume the flight was controlled. A pilot with well calculated intentions I think would not do that. He’d rather dump his last fuel near destination I think.
Your suggestion of setting a final waypoint with a fixed (lower) altitude I find quite interesting. Lets say around 19:41 at 35Kft you set a final waypoint at 29S 98E with a fixed altitude of 15Kft. In which auto pilot mode could this track been flown?
About maximum altitude. Turning back to Malasia from AGARI the plane was tracked at 43.000ft by primary radar so I guess being lighter on fuel it might have reach at least the same altitude if it wished to do that?
@Ge Rijn:
The starting height is important because it determines how the TAS varies with time. In VictorI’s model the airplane initially descends at constant M.84 with increasing TAS, until it reaches a height of 31560 ft, and then descends at constant 310kIAS with decreasing TAS.
@Warren. Just to make a comparison which maybe is silly..
I’m not a pilot but I can sail a boat. And in that situation you mostly have a crosswind cause that’s what you sail on mostly.
And if you want to stay on your course/track you always have to compensate for crabbing.
The nose of your boat won’t ever point to your fixed/chosen track/way-point but a bit against the crosswind.
I guess for a plane its the same.
But offcourse the speeds are much higher and crosswinds won’t have the same (big) effect, for at such speeds (say 400knots)the friction of the air the plane travels through must be very much higher than the friction caused by a sailingboat through water at such low sailing speeds, although water is much denser offcourse.
Coriolis force is clearly a significant force on the aircraft and is around 6000N (for a 777 at 900km/h), that is 0.25% of the gravitational force but of course acting sideways on the aircraft. However, the aerodynamic forces on the aircraft are potentially very large. If a 777 was moving at the same speed, but ‘crabbing’ 0.1degrees from a straight course, I guesstimate the sideways force due to the high speed airflow at 4000N (at 30000ft), roughly the same as the Coriolis force. Therefore, the course deviation due to the Coriolis force is minimal and is swamped by other effects, such as the winds (bulk motion of the air) and out-of-trim forces of the aircraft.
As Gysbreght implied, the aircraft is on rails (the rails being the air).
@JS @Susie
Susie you’re right, most probably a long-forgotten accident – a solemn message in a bottle!
That’s a bloody great find, JS! I never knew about this disappearance, nor do I think many others would’ve either. I’ll definitely read it when I get a quiet moment, I hope others will do the same.
@Victor
Thanks for sharing the link! Your help is always appreciated even if it sometimes takes eons for me to reply back! 🙂
Victor,
Regarding ATT. You are confusing the evidence of absence with the absence of evidence.
I am not a pilot, and I don’t know if there is a specific “push button” to engage ATT mode or not, but I do believe that ATT mode is not for decorative purpose only.
FCOM, Section 11.20.4:
——-
The following functions are inoperative after failure of the inertial reference portion of the ADIRU:
– LNAV
– VNAV
– TO/GA
– LOC
– GS
– FPA
– TRK HOLD/SEL
– HDG HOLD/SEL*
*Note: This function is operative when standby magnetic compass heading is entered on the POS INIT page.
——
Note that ATT mode is not in the list, which is logical because ATT data are supplied by SAARU instead of ADIRU.
While I did not find information specifically pertaining to B777, ATT rotary selector switch is located on ADIRU panel of Airbus A320-200 (see, for example, AAIB Bulletin: 6/2006). Similar thing is with regard to B757 and B767. The following are extracts from:
http://b767ops.blogspot.ae/2014/06/about-irss-and-how-they-work.html?m=1
————
IRS Mode Select Unit (MSU):
C. The MSU contains two rotary mode select switches, one for the left (L) IRU and one for the right (R) IRU. The positions are OFF, ALIGN, NAV and ATT.
(2) The ATT position of the switches places the IRU’s into a reversionary mode of operation. The ATT (attitude) mode is used when failure or total power loss (AC and DC power) is detected in the NAV mode. In this mode, only attitude and heading data is output to the user systems.
————
Of course, you may object that the all this stuff is not applicable to B777. I don’t know as I have not found any references yet. You and Gysbreght mentioned that all this stuff was already discussed. I am asking for the 3rd time: could you please point out where?
@Gysbregt.
So if I understand you well it’s not simply setting a fixed descent rate at -0.1 at 35Kft and then knowing you would end up 3000 miles further around 15Kft at a certain speed?
I may all sound silly but I try to figure this out.
What @Middleton suggested about a fixed final waypoint and altitude I also found quite interesting.
Is it much asked to give your opinion on that one?
Oleksandr, I hand-approved your original post and “disappeared” the second one.
No one will ever know what happened to it.
@Ge Rijn:
When you compare an airplane to a boat you are making some errors. A boat moves through water which you assume to be at rest. The equivalent for an airplane flying through moving air would be water flowing with tide or in a river. What you call “crabbing” for a sailboat would be called “sideslipping” for an airplane, i.e the angle between the airplane’s longitudinal axis and the airspeed it has relative to the airmass it flies through. The crab angle for an airplane is the angle between airspeed and track, i.e. for an airplane with zero sideslip the angle between heading and track over ground.
Sk999,
Re “regarding the use of magnetic heading for travel, yes, it is the normal mode when traveling a fixed heading route, even for commercial jet aircraft.”
You are absolutely wrong. IRU and GPS are used these days, not magnetic compass. Certainly, the magnetic heading is not normal mode.
Re “Most general aviation aircraft do not have IRUs and rely on magnetic instruments for heading information.”
Also wrong. Magnetic compass is used only as backup, especially in commercial jets. You can find IRU even in RC toys these days.
Dennis,
“I’ll just say your understanding of GPS is wrong.”
In my understanding a consumer-grade GPS derives velocity from position. I have also seen somewhere that more advanced GPS may detect Doppler shift and derive speed based on it, not sure about velocity. Since you said that my understanding is wrong, could you please explain why? Your subsequent explanation seems to be consistent with what I thought and what I wrote.
@oleksandr:
“Regarding ATT. You are confusing the evidence of absence with the absence of evidence.”
You are confusing the autopilot mode selections available to the pilot via the MCP (Mode Control Panel) described in FCOM section 4.20, with the Flight Mode Annunciations displayed on the FMA (Flight Mode Annunciator) on the PFD (Primary Flight Display) listed in FCOM section 4.10.
The latter reflect the current status of the AP. That status may and does change without pilot selection if a certain condition or limit is reached. The annunciation of a particular autopilot mode or status such as ATT does not mean that it can be selected at will.
Earlier you wrote: “Because it is listed in the manual as normal mode. It is clearly stated that if flight director is ON, such a mode can be selected.”
I couldn’t find that anywhere in the FCOM. Where did you see that stated?
Cheryl,
“Is the fuel pump needed for fuel dumping?”
Yes. They are called “jettison pumps” (per FCOM). Based on the discharge rate up to 2,500 kg/minute, I can imagine they consume quite much power. I am also interested in which bus they are connected to. Your idea that the left bus could be reconnected for fuel dumping purpose sounds very intriguing.
@Gysbreght. Yes, thats an essential difference. In a sailingboat you would have to compensate for drift (watercurrent) also if there is any and steer against its coming direction.
I mean if your track is on 280degrees to your destination and you won’t compensate for drift your track stays the same but your destination will and up miles from the one you intended.
Gysbreght,
Re: “You are confusing the autopilot mode selections available to the pilot via the MCP (Mode Control Panel) described in FCOM section 4.20, with the Flight Mode Annunciations displayed on the FMA (Flight Mode Annunciator)”
I was never discussing FMA. You are confusing me with somebody else. Read FCOM again as I only posted citations from it.
Gysbreght,
Re: “An airplane travels in the direction its nose is pointing”
Obviously no. Crabbed landing is a classic example.
Oleksandr Posted May 6, 2016 at 5:26 PM:
“I was never discussing FMA. You are confusing me with somebody else. Read FCOM again as I only posted citations from it.”
Oleksandr Posted May 5, 2016 at 4:44 PM:
“Victor,
Citation from B777 operations manual, section 4.10.16.
(…)”
The title of that section is : PFD Flight Mode Annunciations (FMAs).
@Oleksandr: Compare the MSU, which is used to align the IRS via the rotary select switch, with the single button available for the ADIRU to align it. There is no ATT switch for a B777. That’s why you can’t find it even though you can find it for other airframes. You are asking me to prove that the ATT switch does not exist. I can’t prove a negative. But don’t you think it is odd that we can’t find ANY reference to this switch, while many references to an ATT switch can be found for other airframes?
http://meriweather.com/flightdeck/777/over/misc.jpg
@Oleksandr:
Re: “An airplane travels in the direction its nose is pointing”
You probably missed the third sentence of that same post, which read:
“If the airmass it flies through is moving at certain speed and direction, you just have to add that to the airplane’s own velocity.”
Oleksandr,
The following document gives about as good a summary as I can find on true v. magnetic heading conventions, and how different types of aircraft navigate. (General aviation aircraft are the less expensive aircraft mentioned below).
https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/parc/parc_reco/media/2013/130617_PARCMagVarRecommendations.pdf
“Most transport category airplanes (with onboard inertial reference systems) provide true-referenced data; calculate corresponding MAGNETIC data; and use or output data in either or both reference frames. These airplane systems do not need magnetic sensor data because of the onboard inertial systems (such as IRS,IRU, ADIRU). These inertial systems contain MAGNETIC variation coefficient databases, and derive MAGNETIC values from these databases to support displays and other airplane systems requirements.”
“In other types of airplanes, less expensive, smaller, and less accurate heading reference systems depend on other implementations, which may use the Earth’s MAGNETIC FIELD (via a flux valve or flux gate) coupled to a gyroscope or a sub-inertial gyroscope to maintain a three-axis reference (such as in a compass coupler, MAGNETIC heading reference system (MHRS) or airplane heading reference system (AHRS).”
“Airplanes’ area navigation systems perform their calculations based on true
references, but require the ability to navigate in both true and MAGNETIC reference frames because most charts, runways, facility references and ground-based NAVAIDS use MAGNETIC references. In addition, instrument approach procedures, charts and airports use MAGNETIC references. All of these elements (airborne, ground, and flight procedures) must be updated as the Earth’s magnetic field moves.”
There’s more, but hopefully you get the idea.
Gysbreght,
“The title of that section is : PFD Flight Mode Annunciations (FMAs).”
Yes, so what mode ATT corresponds to? Bank > 5 deg?
Gysbreght,
“You probably missed the third sentence of that same post, which read: “If the airmass it flies through is moving at certain speed and direction, you just have to add that to the airplane’s own velocity.””
No, I did not miss. This addition does not change anything. One of the priorities during crabbed landing is to damp rotation caused by cross-wind. Velocity of the aircraft with respect to air may not coincide with the orientation of its roll axis in this case.
You can find more details in:
Sadraey Mohammad, 2012. Aircraft Design: A Systems Engineering Approach. Chapter 12:
Design of Control Surfaces. 792 p. Wiley Publications.
@Oleksandr:
“Yes, so what mode ATT corresponds to? Bank > 5 deg?”
If at AP or FD engagement Bank < 5 deg – the ATT mode exists temporarily while the airplane is rolled to wings level, and the heading or track existing at the time that wings level is achieved is then maintained in HDG/TRK mode. Although the FCOM is not explicit on that point, I think that it is reasonable to assume that when the wings are level the FMA annunciatiation changes from ATT to HDG or TRK, depending on the MCP selection.
Victor, Gysbreght,
So what mode B777 enters if ADIRU fails, given the list of the existing modes from FCOM, and the list of modes which do not function in this case, again, according to FCOM?
I don’t know if it is possible to select ATT like in A320 or not, so I will not argue with this.
Regarding Coriolis forces, the question came up about how the AFDS in heading hold mode would know how to compensate for those forces. It is quite simple. Let’s return to my example of an aircraft flying a great circle path as seen in inertial space. If you point the aircraft in the direction of travel, it will stay there. However, when viewed in a rotating frame, the apparent heading of the aircraft will change. All that the AFDS has to do is sense a change of heading and apply a correction. For our aircraft that appears to be heading South there is a slight acceleration perpendicular to the direction of travel in the West direction. The magnitude is the same as that computed for the Coriolis force. If one wants to think of it as traveling on rails, there is a slight sideways force applied to the train’s wheels, as if it were going around a bend, even though the track is absolutely straight.
@Oleksandr:
“One of the priorities during crabbed landing is to damp rotation caused by cross-wind. Velocity of the aircraft with respect to air may not coincide with the orientation of its roll axis in this case.”
If that is what Sadraey Mohammad writes, then it’s not worth reading it. You probably misunderstood.
@Oleksandr
“”So what mode B777 enters if ADIRU fails, …”
We were discussing your claim that ATT is a ‘normal’ mode of the autopilot, and I’m not going to be side-trecked into failure modes.
@Ge Rijn:
I was looking at a different scenario where there’s a landing/takeoff between 18.25 and 19.41 (VictorI’s ‘loiter’ period) and the ‘pilot’ bales out during ascent (before 10k ft) leaving a new flight plan (the old one being deleted and the new one entered before the AES/SDU reconnected, hence no flight ID sent on the login) to take the aircraft south.
As I understand it, in order to achieve the curving path that would satisfy the ping rings the aircraft would have to fly a magnetic bearing – ie. the magnetic field curves eastwards in that more southerly part of that area and the aircraft would have to follow it.
In the scenario I was looking at, after take off the ‘pilot’ would set an initial waypoint/speed/height (say 10k ft) which would be over the drop zone. Once he’s out, the flight plan would have further waypoints (the next, say, 35k ft and 480 knots). The aircraft would then descend slowly (maybe the -0.1?) to the final waypoint, which might be (say) 250ft and 250 knots (or minimum slow speed) at which the aircraft would stay until fuel exhaustion, then a (relatively) gently wing over into the ocean.
The problem (?) with lat/long waypoints (as opposed to a bearing from a waypoint) is that they’re fixed. But (as I understand it) a curving path could only be achieved with a magnetic bearing, following variations in the earth’s magnetic field.
The 22k ft I quoted was a rough attempt to fit with VictorI’s model where the aircraft lost ~22,400ft from 19.41 to fuel exhaustion. But then you could just let it fly itself into the sea at -0.1 deg. although the speed would be much faster of course, so the wreckage greater.
However, the other discussions and quotes here today bring another factor into the thinking: if the aircraft systems compensate for magnetic variation by reference to an onboard database, then how could the aircraft fly a curving path even if it was programmed to fly a magnetic bearing? Wouldn’t the compensation come into play resulting in the aircraft flying straight?
So to get a (unpiloted) curving path you’d need a set of ‘curving’ waypoints?
But why would a pilot enter that?
This discussion reminds me a lot about symptoms of automation dependency and resulting mode confusion.
You have lost me there.
As I feel somewhat responsible for causing this discussion with my statement some time ago about a possible flightpath without autopilot or pilot input I feel obliged to repeat my statement in short.
The basic aircraft without autopilot or autothrottle or nav mode engaged will not crash, as the FCS in primary mode will keep the aircraft in the air provided, it started with ample altitude with a stable speed and powersetting. FCS will keep the aircraft level and at the set trim speed for quite some time, maybe even until fuel exhaustion.
That’s the basic principle of the stability of a modern FBW Boeing aircraft. I do not think that you will find a switch in the cockpitor a mode designation. The closest name I can come up with is the C*U Law.
Gysbreght,
“If that is what Sadraey Mohammad writes, then it’s not worth reading it. You probably misunderstood.”
I can only suggest you reading some book on mechanics. It will help you to understand such thing as yawing moment and its cause.
@oleksandr:
“I can only suggest you reading some book on mechanics.”
Thanks for your suggestion, but I can think of more useful things to do>
Gysbreght,
“We were discussing your claim that ATT is a ‘normal’ mode of the autopilot, and I’m not going to be side-trecked into failure modes.”
So ATT mode is not normal mode? And if bank angle >5 deg, it should be considered as failure mode? Anyway, if you discussed whether ATT is “normal” mode of the autopilot, it means you entirely missed my point.
@oleksandr:
Would you understand ‘trolling’ mode?
I’m off to bed.
@Oleksandr: The discussion has been about whether a pilot can choose to switch to ATT mode for bank angles less than 5 deg. You insisted the answer is yes. The answer is clearly NO. If there is a failure, or if the performance of the autopilot is degraded, of course an inertial mode is possible so that attitude is stabilized. That was not what we were discussing, and you know it.
Just an interested reader here.
I am having a little trouble getting my head around some of this debate.
To help me (and presumably many others) has anyone here produced a single document, sort of like a “an idiots guide to T7 auto flight modes”, that lists every possible combination of auto flight modes, with a detailed breakdown of what each mode does or “can” do in terms of heading, track, speed, alt hold etc ?
@Oleksandr
“I don’t know if it is possible to select ATT like in A320 or not, so I will not argue with this”
Seems like you did a pretty good job at it.
Anthony – what was that line out of the Simpsons while they were stuck at the bottom of that shaft with hammering away with shovels in their hands? “dig up….not down….stupid!
Can we deduce then that if it’s in the water it’s well to the north and folks who made a temporary science out of BFO-ism can bin it? It’s up in the sort of region where the US/Aust/British Navies went trawling more or less?
@All
I agree that understanding the flight dynamics may lead us to a new place to search for the plane. However, the new drift analysis and @Jeff’s barnacle study seem to indicate that the plane was not flying straight into the sio. In that case it must have been actively piloted and not a ghost flight on autopilot. We need to see what the bfos can tell us about a holding pattern near the coast. Or a northerly track.
@Matty: re: further NE along arc: put me down as a firm “not likely”.
Moving The search box up to ~20-25°S…
– resolves a paradox (explains no debris on Oz shores)
– shifts a paradox (“incompatible with flaperon’s Météo-reported…” shifts from barnacle growth to buoyancy
– intensifies a paradox (harder to explain 22 months of no debris in Africa/surrounding), and
– CREATES a major paradox (“slow & descending” BFO fluke AND [(“slow & curving” BTO fluke) or (magic path circuity undetected by radar, and snuck in between pings)]
I meant it when I said the evidence drives me to “camp 3”. If the debris drift models and analytics are reasonably sound, there is no rational path to the 7th Arc – a conclusion which includes – and thus retroactively predicts – the empty seabed scan results.
I am increasingly confident we have been witnessing theatre in the (runa)round.
@Sajid – the last line is the kicker: the largest airplane to disappear with out a trace.
@Richard Cole – you ran the numbers at 30,000 and came up with a minimal Coriolis effect. What about at 38,000 feet or even 47,000 feet, as 9M-MRA reportedly did over Saudi Arabia?
Brock – I was being as disengaged as I was just talking broadly when I said “up in the region”. I should have just said way up north. Fact is they trawling will be a lot closer to the truth than the seabed scanning.
The trawling was derided as a huge waste of time and money but some key players showed up at least. What’s been going on down there – it makes you wince. I remember Dennis arguing himself ragged – why auto-pilot? No AP for those WW2 boys over Europe and Japan for 10 hours at a time? Freezing cold, pitch black. In totality, it’s all bizarre in an uncomfortable way. Like a lot of spectators I wrote the search off before it started but they were so confident? Was it just MH370 zeitgeist?
Gysbreght wrote:
“You can disengage TRK/HDG HOLD by selecting another mode or by disengaging the AP. If you make an imput on the control wheel to set up a small bank-angle you disengage the AP”
Brian Anderson wrote:
“An alternative to the final turn south being a turn at a waypoint is the possibility that the turn was initiated manually”
RetiredF4 wrote:
“The basic aircraft without autopilot or autothrottle or nav mode engaged will not crash, as the FCS in primary mode will keep the aircraft in the air provided, it started with ample altitude with a stable speed and power-setting. FCS will keep the aircraft level and at the set trim speed for quite some time, maybe even until fuel exhaustion.”
QUESTION — if the a/c was turned manually, say towards Banda Aceh whilst the a/c was still on N571 prior to reaching IGOGU, then could the a/c have been “deflected” by the strong westerly winds at southern latitudes, somehow “tipped” into a bank to port, resulting in a turn of 90 degrees or more, such that the a/c track between 5th – 6th arcs was mostly easterwards or even ENE ?
Perhaps the dramatic change in BFO from 5th to 6th arcs reflects a dramatic course change ? Victorl showed that the BFOs on the 6th / 7th arcs are mostly due to satellite velocity largely independent of position, and that BFOs varied considerably along said arcs. Perhaps, if the a/c was flying without “actively intervening AP” (for want of expert terminology), then a dramatic change of direction, a second FMT, eastwards and northwards towards Australia, could (help) account for the considerable change in BFOs ??
@Brock McEwen.
Some thoughts on your summery.
Moving the search box up to ~20-25S..
-removes a paradox; explains no debris on Oz shores. But imo it creates another one: no debris found on the densely populated shores of Java, Sumatra, Bali (whole region there)or on African coasts north of Mozambique.
-shifts a paradox: incompatable with flaperons shift from barnacle growth to buoyancy. In natural order it must have been the other way around: shift from buoyancy to barnacle growth (submerged). Imo its impossible for the flaperon to shift from submerged to buoyancy while still in the water. In some mysterious way it has to drain all or a lot of its internal water while being submerged in the water. Then it must have been at some point out of the water, drain its internal water and get back in the water to get filled up again. Very unlikely if not impossible imo.
The drifting scenario rather would have been a combination of the two states imo.
It started with a lot of buoyancy leading edge down (heaviest part) picked up wind and travelled relatively fast. It (very) slowly filled up with water loosing buoyancy and wind speed until it got (almost) submerged completely traveling only with the speed of the current and allowed barnacles to grow on all sides from that point on. Maybe thats way the barnacles on the leading edge are the biggest for that part was never out of the water?
I realise this implies there must be some flaw in the DGA-study. Maybe they didn’t took the time (are had not the time) it would take for the flaperon to fill up with water?
-intensifies a paradox: the 22 months of no debris of no debris in Africa/surroundings.
Imo a flaperon drift scenario like above could lift this paradox.
-creates a major paradox: the flight path.
This surely stands. Even more between ~20-25S imo.
altitude FX ?
what happens as the a/c, trimmed to compensate for fast westerly winds aloft, descends towards sea level, where wind speeds decrease ?
would the a/c veer westwards from being over-trimmed ?
Kerguelen Island is near the 7th arc.
KI was the subject of the Sept. 2008 song, “Loneliest Place on the Map”, by Al Stewart, on the album “Sparks of Ancient Light”, most of whose songs deal with very sensitive Religious & political issues, e.g. “Elvis at the Wheel”.
The chorus of the KI song is:
“It’s the loneliest place on the map
And night time is utterly black
I came here by some grave mishap
And I can’t find my way back home”
Guess I hope there’s a cure for “Multiple Scenario Syndrome” 🙂 but the album theme, generally, and song lyrics, specifically, resonate with the mysteries surrounding MH370, such as the captain’s famous black politically-charged shirt.
QUESTION — would the coordinates of KI (~70E, 50S), if hypothetically entered into the FMC, have powered the a/c towards the SIO, on a flight-path consistent with all BFO and BTO data values ?? “Super-high super-fast” FL4300+ M0.84+ ??? The captain set the a/c on a route into mystery & history and slowly drifted off into blissful sleep as heat & air leaked out of the fuselage ??
Victor,
Re “The discussion has been about whether a pilot can choose to switch to ATT mode for bank angles less than 5 deg. You insisted the answer is yes. The answer is clearly NO.”
The discussion started from Jeff’s question what automated (ghost) modes can lead to 30S. I expressed a thought about ATT, and that ATT mode can be engaged as in other aircrafts of similar ‘caliber’. A320, for example, has ATT switch on IRU panel. I don’t see a clear answer “yes” or “no” from FCOM. Can you please point out any reference to your definite “no”?
Re: “If there is a failure, or if the performance of the autopilot is degraded, of course an inertial mode is possible so that attitude is stabilized. That was not what we were discussing, and you know it.”
This was exactly a point of my discussion, and I am sorry if I did not make it sufficiently clear. One issue is that what stable horizontal modes besides TRK HOLD, HDG HOLD and LNAV are possible on B777, and the other issue is how an aircraft can enter these modes. My point was that the 5 modes you listed, 2 of which correspond to probably non-existing magnetic heading, are not only the ‘normal’ operating modes resulting in a ghost flight. Under ‘normal’ I meant a legitimate mode, when aircraft operates as it is supposed to in the respective mode. Whether ATT mode can be manually selected or not is only a sub-topic of this discussion.
In summary, do you agree that a B777 can fly in ATT mode with bank angle <5 deg without human input?
Below is the link to AAIB bulletin I mentioned in previous posts:
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/384888/Bulletin_6-2006.pdf
@JDB
Thanks very much for the translation.
So,assuming this report is solid and as others have said, we are left with the paradox of how this could float relatively high, partly above the water surface and still have substantial barnacle growth all around. Hmmm…
The rotary switch on the ADIRU panel controls the output of the Inertial Reference (IR) part of the ADIRU. In the ATT position of that switch the affected ADIRU (1, 2 or 3) only provides attitude and heading information, but does not provide navigation data such as groundspeed, windspeed, track, and latitude/longitude. The switch does not select an autopilot mode. I doubt that A320, A330 autopilots even have an ATT mode comparable to that on the B777.