MickJoeBil -
Seriously, that has to be one of the dumbest proposals ever from a flight simulator expert on this topic.
If you ever get around to operating multi-crew aircraft you'll understand why from a common sense point of view very quickly.

Porterhouse...

"(say based on radar returns, I don't think they explained how)"

You put an edit in there !
Because that is the "bit" I couldn't work out.

Increased work (eg) increased speed (or lower altitude) equals shorter distance travelled.

They would have had to model various scenarios to move the whole SAR effort....or it was "other" information.

Well I hope they are right.
And from early indications (the latest P3 reports) they maybe correct.

The aircraft trades potential energy (altitude) for speed as it noses down and accelerates. This eventually creates additional lift, reversing the descent. The process repeats. But a glider can't do this forever and eventually comes down.

This clear illustrated example from Aerospaceweb can help explain it more fully:

Aerospaceweb.org | Ask Us - Lift, Wind & Porpoising

Very interesting development re possible investigation !

Push to take control: Australia to lead the probe into MH370

The air crash investigation into the ill-fated Malaysia Airlines flight MH370 is likely to be based in Australia, amid a push for the wreckage and the black box to be scrutinised here.

In a day of significant developments in the search for the lost flight, the Malaysian government announced it won't establish an inquiry until the black box - or flight recorder - is found, something that could take years, if it is even discovered at all.

The decision created uproar in Malaysia's parliament amid lingering concerns about the nation's investigative effort thus far, which has been characterised by mistakes and miscommunication and enraged some families.

Ok Stupid :) (sorry - only joking)

I am sure someone will correct me (or just delete this post) if I am wrong but I think the way this was presented was very confusing. It is my understanding that what was said was that the examination of the data they have from the early part of the flight (radar tracks from various sources I think) has suggested that the plane flew faster FOR THAT PART OF THE FLIGHT which used more fuel in the initial stages. By working with what fuel was on board at take-off and then estimating fuel usage for the initial flight that was tracked they have come up with an estimate of the fuel onboard when radar contact was lost.

They know (or are pretty sure) that the plane was still airborne at the time of the last full ping so they can work out what the endurance was (but not exactly because the plane could have run out of fuel right after the last ping or up to 59 minutes later). Based on the fuel available and endurance you can work out what airspeed would give the correct timing. If the plane had less fuel when it started the track south then in order to still be airborne at the last ping they have now deduced it must have been flying slower than initially thought FOR THAT SOUTHWARD part of the journey - hence the plane has not travelled as far south as their initial estimate.

Also I assume from the pings they have they know what the distance from the satellite was at each ping time so if the plane was travelling slower it was also on a more easterly path to put it on the right distance from the satellite at each point.

Hence why the search area has moved north and east due to the plane flying faster at the start, using more fuel and having to fly slower at the end to make the duration correct.

As an aside can any 777 people give a rough idea of what speed does give you maximum range at cruising altitude? It would seem to me that IF it was intentional and they wanted the plane as far south as possible then they would have gone for max range speed rather than anything else. Although the more easterly track doesn't seem to tie in with that as you would assume you would want to be further away from Australia if possible (unless of course you were aiming for a particular seabed location for the wreckage).

Posted by suninmyeyes:


Thank you sir for a very informative post based on real evidence from simulator ops instead of conflicting "opinions".

Generally speaking, the faster an aircraft flies, the shorter will be its range.

To achieve the maximum range, there is an optimum speed an aircraft (any aircraft) must fly. If the aircraft is flown at a speed greater than the optimum, the range will be less than maximum. If flown at a speed slower than optimum, the range will again be less than maximum.

There is ONE optimum speed for maximum range. That speed tends to be quite a bit slower than normal cruising speed however, so it is only used when maximum range (or maximum fuel conservation) is required.

It makes perfect sense for the authorities to say "the plane travelled less distance because it was travelling faster".

The same is true for your car. There is one speed for maximum distance. Drive faster than that and you won't be able to go as far. Drive slower than it, and again you won't go as far. It is all to do with the magnitude of the drag forces (and engine efficiency), which vary enormously with speed.

Low frequency sound requires a larger and more powerful source, plus it is more difficult to localize. ELTs have severe size and power limits, so a high frequency noise to pinpoint the source makes sense.
The ELT design requirements may now get another look, as very long range trans oceanic flights have become much more frequent and the ELT is becoming more critical. However, given the unhappy experience recently with a runaway ELT damaging a 787 at Heathrow, people are unlikely to embrace bigger, more powerful ELTs. The insurance industry will work with the aircraft makers to come up with a better system, something that leaves a reliable breadcrumb trail for every flight.

I would be fairly confident to say no bureaucrats are involved in any calculations.

Common sense will tell you this, to much of a political football and its easier to point the figure at a boffin if its wrong.

There is a huge amount of extremely talented people putting their all into trying to solve this. A lot will be going way beyond what they are paid for and its very insulting to them to imply they are bumbling fools.

Everyone knows that there is an optimum speed for distance of travel for a given amount of fuel and hence, that any vehicle traveling faster than the optimum speed will travel a shorter distance in a shorter time. Using the faster = shorter explanation hence provides some specious credibility to what really is an admission of previous mistakes.

The current location is shorter than the previously estimated position for a KNOWN TIME 8.11, which was based on a slower speed. That's impossible. Perhaps they know something knew, which they are not sharing. Perhaps the 8.11 ping is a myth.

141 Battery Incidents 20 March 1991 to 17 Feb 2014

http://www.faa.gov/about/office_org/...dent_chart.pdf

I remember reading about the 12-Apr-1999 case where two pallets of CR2 batteries. One pallet was damaged by a fork lift and it was some hours later that to caught fire and there was difficulty in putting it out.

This was after a pax flight from Japan and happened at the airport, but it just as well could have happen in the cargo bay.

What type of fire detection system was used on MH370, Ionization smoke, optical smoke, flame, high temperature, etc?

I think one thing that may have been overlooked, is how far north of Banda Aceh the plane would have had to have flown to avoid Indonesian radar (they said they didnt track it)....So, if we concluded and calculated that the plane ended it's trip sometime not long after the partial handshake, it was in the air for a total flight time of somewhere around 7.38 to *unknown* extra minutes. Let's "speculate" that it was 8hrs. We "conclusively" know about 1:34 (initial flight and turn back), which takes us over Pualu Perek. What we dont know is how long the flight continued north so as to avoid turning over Indonesia. If we said "okay...30 minutes" and then turned south...that takes off 2:00, leaving remaining flight time of somewhere around 6 hours. Lets then "speculate" that the plane turned somewhere 300km past Indonesia, so as to avoid Indonesian radar. "If" the plane maintained a speed of 850kmh (only saying that as it seems a lower flight level=lower speed and it "may" have lowered its flight level according to the reports), then "unknown" travel (after disappearing!) would be somewhere near 5100km....Take off 300km (avoidance of Indonesian radar), then its 4800km. That would mean the crash zone could not be below Perth....Actually somewhere west of Geraldton would be closer.
I understand that this is all "speculation", but so is pretty much everything else at this point :uhoh:

One thing we do not know which may have affected the range of the aircraft is exactly how far WNW it flew from Butterworth. It appeared to drop off primary radar at 200nm. Further elucidation of this may have been possible by data collected by other agencies not disclosed for security reasons.

However, if this is so, it does make it even more confusing that the final position appears to be closer to Perth. It would help to explain the time and speed, however.

Mises,


Not impossible at all when you consider that the only thing they have to work with is the Doppler shift values.


When you have only the Doppler shifts, the only thing you know is the speed of the aircraft RELATIVE TO the satellite. You don't know the distance between the two, and nor do you know precisely the track of the aircraft.


You can estimate a track, based on an assumption of the aircraft's true speed. If you assume a different speed, however, then the entire track direction changes, as does each ping position along it.


If the estimated track had stayed the same, then I would agree with your "impossible" claim. But note that they have come up with a new track.

They know the distance from the satellite by the ping response time, and that is the 40° degree arc.

The pings DO set the timeframe, and the point of fuel exhaustion is almost certainly when the partial ping was received AFTER 8:11, as the APU and/or RAT took over electrical generation (causing the satcom to re-set and send a new initial handshake request).

They flew faster for a shorter distance still doesn't pan out.

Maybe I have missed something but it seems that calculations of final position based on satnav pings is assuming the signal received at the satellite is strictly Line Of Sight, which may not be the case. There is a well known phenomena called Tropospheric Ducting

E-skip, tropospheric ducting and other VHF propagation phenomena « Engineering Radio

,amongst a few other VHF propagation effects that typically occur in areas of temperature inversions (warmer air above cooler air). Under these conditions VHF signals can travel far beyond LoS range making it nearly impossible to determine the position of the transmitting station.

As a young amateur radio operator I remember holding a conversation with a man in Houston from my apartment in Austin (~200km) using a low power 146 MHz walkie talkie. Since then I have listened to conversations between two people in Louisiana as clear as if they were across the neighborhood as well as an equivalent discussion originating in Oklahoma.

There is a chance, no matter how remote, that the emissions from MH370 could have been caught in a tropo duct for a considerable distance and emerge generally pointed skyward where the satellite picks it up. In that case the ping timing calculated doppler effect may point to a spot the actual aircraft never passed through.

Pure supposition, apart from flightaware or pprune forums there is absolutely nothing out there with minimum credibility that confirms it.

tropopause
 

It is all at lower altitudes if the plane was above 20,000 would not have any affect as signals would be going up at 15-25 degrees not down to the sea, air is dry and rh is very low (basic met) SALR DALR
If the sat was low on horizon maybe could like when you look and see the black inversion layer but above an inversion layer signals are refracted up not down

Yes you did, the satellite was high above Indian Ocean, no over the 'horizon' effect applies.