Malaysian Airlines MH370 contact lost
Join Date: Nov 2013
Location: California
Posts: 154
Likes: 0
Received 0 Likes
on
0 Posts
Could someone just run the following bit of physics past them to see if I have got the important point about the Doppler shift right?
If the satellite was absolutely fixed then the Doppler shift would be the same irrespective of whether the plane was heading north or south BUT the sun and moon cause a slight - but predictable - wobble in the orbit of the satellite and since that wobble is also N/S that will add a very small but measurable extra value in the existing Doppler shift. If the satellite was heading south at the same time as the plane then the Doppler effect would be squeezed by a tiny bit and the wavelength decreased - ie very slightly blue-shifted. If the satellite was moving north whilst the plane was heading south then the radio wavelength would be stretched - very slightly red shifted.
Have I got that correct ?
If the satellite was absolutely fixed then the Doppler shift would be the same irrespective of whether the plane was heading north or south BUT the sun and moon cause a slight - but predictable - wobble in the orbit of the satellite and since that wobble is also N/S that will add a very small but measurable extra value in the existing Doppler shift. If the satellite was heading south at the same time as the plane then the Doppler effect would be squeezed by a tiny bit and the wavelength decreased - ie very slightly blue-shifted. If the satellite was moving north whilst the plane was heading south then the radio wavelength would be stretched - very slightly red shifted.
Have I got that correct ?
The rest is correct.
ELT activated within the aircraft.
I once had a passenger ELT activate accidentally.
((helicopter offshore ops) everybody has one plus the 2 on the helicopter, one jettisoned by impact or manually, plus the 2 in the rafts))
We could hear it but one of our helicopters less than 20 NM away could not.
I presume that the 777 fuselage is much "thicker" re radio emissions than a helicopter so perhaps an ELT activated within with no external antenna would not be picked up by SARSAT.
((helicopter offshore ops) everybody has one plus the 2 on the helicopter, one jettisoned by impact or manually, plus the 2 in the rafts))
We could hear it but one of our helicopters less than 20 NM away could not.
I presume that the 777 fuselage is much "thicker" re radio emissions than a helicopter so perhaps an ELT activated within with no external antenna would not be picked up by SARSAT.
Crash axe and/or stuff from the galley or the cabin itself in the hands of multiple desperate People fighting for their lives would surely finally take its toll on the door and/or the floor.
It is therefore rather likely that at least in the latter phases of the flight no one in the cabin was conscious. Potentially in front of the door no one either.
What caused this is the big mystery for which we can only hope the CVR/FDR to be found and readable.
Join Date: Aug 2001
Location: Greater Aldergrove
Age: 52
Posts: 851
Received 0 Likes
on
0 Posts
As a one time PPL and regular SLF, I have not posted up to now, as I have no authority to discuss the matters at hand. Some of the technical input from the professionals on the site has, however, been incredible...and testimony to their knowledge.
So I'm not about to begin speculation, rather ask one question, and pose another. Firstly, if they are recovered, will the on board recorders offer any useful data? I ask this as I understand (maybe wrongly) that they overwrite after some time.
Secondly, given that it has taken (at least publicly) two weeks for the authorities to locate MH370, is now the time to mandate real-time location transmission? Had this been available for MH370, the military could have intercepted the aircraft in the early stages of their deviation from flightplan...if not to prevent anything, at least to understand it.
Whatever happened, I hope the poor souls on board were unaware of their fate.
So I'm not about to begin speculation, rather ask one question, and pose another. Firstly, if they are recovered, will the on board recorders offer any useful data? I ask this as I understand (maybe wrongly) that they overwrite after some time.
Secondly, given that it has taken (at least publicly) two weeks for the authorities to locate MH370, is now the time to mandate real-time location transmission? Had this been available for MH370, the military could have intercepted the aircraft in the early stages of their deviation from flightplan...if not to prevent anything, at least to understand it.
Whatever happened, I hope the poor souls on board were unaware of their fate.
I ask this as I understand (maybe wrongly) that they overwrite after some time.
Secondly, given that it has taken (at least publicly) two weeks for the authorities to locate MH370 --
, is now the time to mandate real-time location transmission?
Since it has not been confirmedHad this been available for MH370, the military could have intercepted the aircraft in the early stages of their deviation from flightplan...if not to prevent anything, at least to understand it.
Last edited by Lonewolf_50; 24th Mar 2014 at 22:22. Reason: spelling errors
Media reports said last night that there are "no survivors".
The Prime Minister's statement and Malaysian Airlines statement did not state that there are "no survivors".
They said the "flight was lost" and the PM's statement and condolences were certainly downbeat to reflect the probability that all have perished.
The Prime Minister's statement and Malaysian Airlines statement did not state that there are "no survivors".
They said the "flight was lost" and the PM's statement and condolences were certainly downbeat to reflect the probability that all have perished.
Join Date: Aug 2001
Location: Greater Aldergrove
Age: 52
Posts: 851
Received 0 Likes
on
0 Posts
Thanks Lonewolf...
I'm assuming the Malaysians themselves would have taken an interest...given the initial track back towards Malaysia, without any comms.
A fair point...but for me, two factors would sway it the other way. First, the number of lives on board a 777. Second, the damage that aircraft can potentially do.
The military from what nation?
IMO, no. Other opinions will differ. Automobile designers are not required to design their cars for the cases of people who run them off of cliffs. I see no reason, given how many flights take off and land each day the world over by people using aircraft for their intended purpose, to make such a rule when a great deal of tech is already required and installed to keep track of where aircraft are and are going.
Join Date: Mar 2014
Location: wales
Age: 81
Posts: 316
Likes: 0
Received 0 Likes
on
0 Posts
What could the military do
Shoot it down quicker end I suppose and more chance of finding fdr/cvr with 100+ chinese om board would have thought there would have to be agreement by which time out of fighter range.
If not an accident and perpetrators conscious might end up with a nose dive and accusations that the military had forced the end.
Can't see they could force it down or help it down.
Shoot it down quicker end I suppose and more chance of finding fdr/cvr with 100+ chinese om board would have thought there would have to be agreement by which time out of fighter range.
If not an accident and perpetrators conscious might end up with a nose dive and accusations that the military had forced the end.
Can't see they could force it down or help it down.
Join Date: Dec 2013
Location: Auckland
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
...would the cabin crew have activated one of the ELTs especially if they found the biz class sat phones were not functioning?
I am not sure that a crew member on MH370 would have thought of that either given the varying scenarios.
I'm sure that given the outcome of the investigation there will be mandated changes for not only tech crew but also cabin crew too.
Cheers for the insight. Might have to incorporate that into a briefing!
Join Date: Aug 2001
Location: Greater Aldergrove
Age: 52
Posts: 851
Received 0 Likes
on
0 Posts
What could the military do
Surely getting eyes on the aircraft could only be beneficial...
Join Date: Nov 2006
Location: Berks
Posts: 125
Likes: 0
Received 0 Likes
on
0 Posts
AMSA has undertaken a risk assessment and determined that the current weather conditions would make any air and sea search activities hazardous and pose a risk to crew. Therefore, AMSA has suspended all sea and air search operations for today due to these weather conditions.
Join Date: Apr 2000
Location: Canberra, ACT, Australia
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
AMSA Search postponed today
AMSA has advised that the search has been postponed for today due to bad weather in the search area. No planes flying and the Success has left the immediate area because of the weather.
"Due to rough seas, HMAS Success departed the search area early this morning and is now in transit south of the search area until seas abate. A sea state ranging between 7 to 8 is forecast today with waves up to two metres and an associated swell of up to four metres.
The area is also forecast to experience strong gale force winds of up to 80km/h, periods of heavy rain, and low cloud with a ceiling between 200 and 500 feet."
The Success was not able to locate either of the items spotted by the Orion yesterday (and with that weather forecast you can assume they are not going to be anywhere near where they were by the time the weather improves.
"Due to rough seas, HMAS Success departed the search area early this morning and is now in transit south of the search area until seas abate. A sea state ranging between 7 to 8 is forecast today with waves up to two metres and an associated swell of up to four metres.
The area is also forecast to experience strong gale force winds of up to 80km/h, periods of heavy rain, and low cloud with a ceiling between 200 and 500 feet."
The Success was not able to locate either of the items spotted by the Orion yesterday (and with that weather forecast you can assume they are not going to be anywhere near where they were by the time the weather improves.
Join Date: Apr 2000
Location: Canberra, ACT, Australia
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
Something would wash up, on the West (or possibly South) coast of Aus IF it crashed where they are searching.
This is costing the Chinese massively in Satellite resources.
Photo reconnaissance satellites typically follow a polar orbit. This goes over both poles, whilst the earth rotates underneath, so they spend equal amounts of time in the northern and southern hemispheres.
The timing of the orbits puts them over their targets early in the morning or late in the afternoon, in sun synchronous orbits, to get 3D perspective.
To change orbit to look at a different target uses up manoeuvre fuel. They obviously only have a finite amount of this so using it is incredibly expensive in terms of the life of the satellite.
Photo reconnaissance satellites typically follow a polar orbit. This goes over both poles, whilst the earth rotates underneath, so they spend equal amounts of time in the northern and southern hemispheres.
The timing of the orbits puts them over their targets early in the morning or late in the afternoon, in sun synchronous orbits, to get 3D perspective.
To change orbit to look at a different target uses up manoeuvre fuel. They obviously only have a finite amount of this so using it is incredibly expensive in terms of the life of the satellite.
Yaogan-19 is apparently a recently-launched Chinese spysat:Launch News Long March 4C launch with Yaogan 19, November 20, 2013 - Orbiter-Forum
Here's a list of times and inclinations for its passes with respect to 42S 95E which is more or less where they've been looking.
YAOGAN 19 - All Passes
(As far as I know the site mixes historically accurate information with predicted passes).
You'll see that it flew directly overhead at 16:47 (UTC) on the 21st March. Also that it is predicted to do so at 16:47 on the 28th of March; and that it did so at 16:47 on the 14th of March, and the 7th, and so on, going back for months.
No changes in orbit.
(NB that it goes *directly* overhead once per week, but that every day there will be at least one pass where it is reasonably high in the sky).