PPRuNe Forums


Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Closed Thread
 
Thread Tools Search this Thread
Old 28th Mar 2014, 17:51   #8541 (permalink)
 
Join Date: Jan 2006
Location: US
Posts: 1,815
AAKEE- 3500, and perhaps 4000 nm, would be a reasonable estimate.

Optimum performance would start at approx FL 380 and increase as the aircraft weight was reduced with fuel burn off.

Range at very low altitude would be around 60-70% of it's high altitude range but the endurance at low altitude would be very similar (90-95%?).
misd-agin is offline  
Old 28th Mar 2014, 17:52   #8542 (permalink)
 
Join Date: Mar 2014
Location: Below glidepath
Posts: 15
Partial ping

From what I can infer from the comm protocol, the partial ping was initiated by the aircraft. I won't speculate on why. The satellite did not know to initiate the ping.

IMHO:

The partial ping can be analyzed for doppler and that might give some indication of position. However, since only one satellite is involved, this would produce a curve of possible positions, with an associated uncertainty, not a point.

Unless there was a complete handshake with the satellite (ie. aircraft sends ping to satellite, satellite replies, aircraft replies) timing data would not be generated, so one can not calculate a corresponding curve for aircraft position due to timing.

I have not analyzed the time and doppler information (don't have the proper tools in place and would take to long to generate - would rather work on my boat), but from experience on other systems, these might create somewhat orthogonal or independent curves which at their intersection would produce a position. Just speculating.
RichManJoe is offline  
Old 28th Mar 2014, 18:06   #8543 (permalink)
 
Join Date: Dec 2006
Location: Florida and wherever my laptop is
Posts: 1,044
Quote:
Originally Posted by Pontius Navigator View Post
That was the assumption by the INMARSAT guy who thought the aircraft was trying to handshake.
The aircraft systems logon to the satellite(s) by calling them first then they are polled at intervals to check that their receiver is still ready and the low level link is still good. If the aircraft system thinks it has lost the signal - say due to a power down then back up - it might try to restart the lost link. As this last ping was from the aircraft and out of time, it is possibly another log on attempt from the aircraft system that was interrupted.
Ian W is offline  
Old 28th Mar 2014, 19:36   #8544 (permalink)
 
Join Date: Nov 2013
Location: California
Posts: 154
Quote:
Originally Posted by RichardC10 View Post
3. Changing the assumed speed would cause problems for the Doppler model that INMARSAT used. This is very sensitive to the aircraft speed which has to be removed to reveal the spacecraft Doppler signal used to decide it was on the Southern route.

If (if) the interim ping arcs are being used and are still constraining the choice of route and hence search area, I would guess that the constant magnetic heading option is now being used, which allows a shorter required range.
Consider the following.

Doppler shifts are measurements of "radial speed": speed with which the aircraft is getting closer to or further away from the satellite.

If you have a bunch of speed values and you assume that the trajectory is reasonably smooth (no zigzagging), you can calculate the change in radial distance (ie arc) by summation of speed*time.

In other words, if the aircraft is moving in a smooth manner, Doppler shifts and arcs are not independent sources of information. You can fit a number of trajectories to the Doppler shift curve, but, as long as they fit, all points always end up on the same arcs. The unknown is the transverse speed and the transverse distance traveled: how far along each arc your points end up.

So, if we take the previous search point and recalculate the trajectory using lower speeds, all points move northeast and the point of last transmission moves northeast quite a bit, while staying on the ~40 degree arc.

If you look at my spreadsheet a couple of pages ago, I had possible Southern routes worked out for 400 knots and 450 knots, and the results were as expected: going from 450 to 400 moved the endpoint 4 degrees north and 5.5 degrees east.
hamster3null is offline  
Old 28th Mar 2014, 19:43   #8545 (permalink)
 
Join Date: Sep 1998
Location: wherever
Age: 48
Posts: 1,526
Of course the assumption that the final range was based on fuel starvation could be false in which case you have a wider search arc.
FE Hoppy is offline  
Old 28th Mar 2014, 20:03   #8546 (permalink)
ekw
 
Join Date: Apr 2004
Location: Hong Kong
Posts: 42
Quote:
I do not buy crew and without solid evidence think they deserve some respect media rubbish or no media rubbish.
So if a bus disappears off a deep ravine you would be prepared to suspect all causes except the driver? Your position is illogical. Any cause which has not been eliminated must stay in the running. Most rational people can distinguish between speculation and fact. I concede that large sections of our media do blur the lines at times, but that is in their nature.
ekw is offline  
Old 28th Mar 2014, 20:07   #8547 (permalink)
 
Join Date: Jul 2013
Location: Dubai
Posts: 91
The satellite/satcom provided the "pings".
Doppler analysis provided direction.

What process/data provided fuel burn/speed/altitude calcs ?
Must have missed it.
JamesGV is offline  
Old 28th Mar 2014, 20:09   #8548 (permalink)

 
Join Date: Jan 2008
Location: Australia - South of where I'd like to be !
Age: 53
Posts: 4,258
So, a new day, is it today that we will get some recovered "something" ?

IF something is recovered from the aircraft, we will get another media storm.

If they don't find something by Sunday evening AEST, I question if they will.
500N is offline  
Old 28th Mar 2014, 20:17   #8549 (permalink)
 
Join Date: Jan 2008
Location: Hotel Sheets, Downtown Plunketville
Age: 70
Posts: 568
I find it surprising that the US Navy has not tasked an aircraft carrier to assist. The avialbility of such vessels would greatly assist by substantially increasing time over the search area conducted by carrier based aircraft.

Perhaps some on this forum with better knowledge of US Naval fleet ops could enlighten us.
Chronus is offline  
Old 28th Mar 2014, 20:29   #8550 (permalink)
 
Join Date: Nov 2013
Location: California
Posts: 154
I tried to recalculate the northern route as well using lower speeds (400-420 kts).

At all speeds, it slices off a bit of Eastern India, goes above Himalayas between Nepal and China, and terminates in Tajikistan or Kyrgyzstan.

Below 420 kts it may never even get out of the mountains: there's a pretty formidable and desolate mountain range with peaks up to 23000' across the route along Tajikistan/Kyrgyzstan border, right in the area where the "partial ping" could have come from at 400 kts.

I know, I know, "how come no one saw it on the radars?" Suppose that Indians missed it for whatever reason. Nepal has no radars and even no air force. The rest of the way is over pretty rugged terrain, mostly above 15000'. My routes even pass in the vicinity of K2. We already heard that the aircraft flew lower than normal (FL295) in the Straits of Malacca. Flying FL295 in the Himalayas could significantly limit its exposure to radars.

The biggest thing I don't like about this is that slower routes take it into the southwestern corner of the Tibetan Plateau. It's still pretty desolate, but it's flat and the aircraft could be visible to Chinese military radars if there are any in the vicinity.

P.S. If you think that Tajiks would have reported a big aircraft crashing into one of their mountain ranges or at least would have gone to look for it, then a) the area we're talking about looks roughly like so http://www.panoramio.com/photo/49758018, and b) Tajiks have bigger problems than looking for other people's lost aircraft: http://en.itar-tass.com/world/725561

Last edited by hamster3null; 28th Mar 2014 at 20:43.
hamster3null is offline  
Old 28th Mar 2014, 20:44   #8551 (permalink)
 
Join Date: Jan 2008
Location: Hotel Sheets, Downtown Plunketville
Age: 70
Posts: 568
The Pacific based US 7th Fleet has despatched a second P8 Poseidon Patrol aircraft to join the search today.
In terms of mission effectiveness and reliability, the P-8A represents a leap forward for the Navy's maritime patrol and reconnaissance community. The aircraft has a maximum speed of 490 knots, a ceiling of 41,000 feet, and provides a range of more than 1,200 nautical miles with four hours on station. For a mission such as the MH370 search, the P-8 will typically fly at 5,000 feet at 350 knots, dropping to 1,000 feet to get a visual identification of any radar returns. It may also fly at 1,000 feet for an extended period of the flight, depending on the environment and mission for the flight. It has a search time of approximately eight, nine hours depending on distance to search area, though during this mission the search time on station is greatly reduced due to the distance of the search area from Perth.

The emphasis is "search time on station is greatly reduced due to the distance of the search area from Perth."
Chronus is offline  
Old 28th Mar 2014, 21:44   #8552 (permalink)
 
Join Date: May 2011
Location: Kent
Posts: 6
Fuel consumption

I'm confused by the announcement about the new search area and would appreciate it if anyone could explain it to me (fascinated by aviation but not a pilot).

So, we have been told that:
- MH370 sent a series of pings that have helped us understand how long it flew for
- It was originally reported that it had flown at high altitude and thus flown a certain distance (high altitude flight being more efficient)
- it is now reported that it flew faster and therefore used more fuel
- the primary search area has been moved Northwards and somewhat Westwards

It is this part that I'm battling to understand. If we know how long it was flying, and it is now reported that it flew faster, why has the search area been moved closer to the origin? Surely if it flew for the same length of time at a higher speed it would have flown further?

I'm sure I'm missing something but I can't see what

Thanks!
RGN01 is offline  
Old 28th Mar 2014, 21:44   #8553 (permalink)
 
Join Date: Jul 2013
Location: Dubai
Posts: 91
1,100 km N/E

Still can't grasp this.

Given new analysis, it is believed that MH370 was travelling at (quote) "a higher speed than previously thought".
This information was supplied by the chaps at the NTSB.

Leg 1 calculated via Secondary radar. Leg 2 estimated via Primary.
Leg 3, how do you work out the "speed" (K ?) for this leg ?

You could use the data collected from leg 2 ...and assume it was then a constant ?
Thus assuming speed and alt you'd get burn and therefore a lesser distance ?

Any ideas how this was arrived at ?
JamesGV is offline  
Old 28th Mar 2014, 21:58   #8554 (permalink)
 
Join Date: Jul 2006
Location: Oxford, UK
Age: 39
Posts: 35
Malaysian Airlines MH370 contact lost

JamesGV

Maybe the new analysis came from RR.
igs942 is offline  
Old 28th Mar 2014, 21:59   #8555 (permalink)
 
Join Date: Dec 2006
Location: Florida and wherever my laptop is
Posts: 1,044
Quote:
Originally Posted by RGN01 View Post
I'm confused by the announcement about the new search area and would appreciate it if anyone could explain it to me (fascinated by aviation but not a pilot).

So, we have been told that:
- MH370 sent a series of pings that have helped us understand how long it flew for
- It was originally reported that it had flown at high altitude and thus flown a certain distance (high altitude flight being more efficient)
- it is now reported that it flew faster and therefore used more fuel
- the primary search area has been moved Northwards and somewhat Westwards

It is this part that I'm battling to understand. If we know how long it was flying, and it is now reported that it flew faster, why has the search area been moved closer to the origin? Surely if it flew for the same length of time at a higher speed it would have flown further?

I'm sure I'm missing something but I can't see what

Thanks!
The fuel burn rate increases so that although the aircraft is flying faster it will run out of fuel earlier after a shorter distance. It will also be less affected by winds as it was faster.

Range speed of an aircraft (where it gets the most range) is not normally at particularly high Mach No. for the aircraft. Endurance speed of an aircraft (where it stays airborne longest) is slower and less range than range speed.
Ian W is offline  
Old 28th Mar 2014, 22:00   #8556 (permalink)
 
Join Date: Mar 2014
Location: WA STATE
Age: 72
Posts: 326
RE NAVY P8

P8 was designed/built to be aerial refueled with long boom typical of Air Force- whereas normal navy is probe and drouge.

It is still in early deployment- some issues with electronic suite still remain

It takes many months of training and certification to do such refueling

Probably not scheduled till 2015-2016 for such training and certification

Only a few have been put into operational use so far.
CONSO is offline  
Old 28th Mar 2014, 22:04   #8557 (permalink)
 
Join Date: Nov 2005
Location: Potomac Heights
Posts: 366
Let me repeat something. Where the plane crashed and where the current search zone is are two interrelated, but different things. The search zone is where 20 days of ocean currents and winds are believed to have moved things after the crash occurred. The fact that the search zone has now been moved to a location that is northeast of the previous zone does not mean that the crash site has also been presumed to have moved by an equivalent displacement. Ocean winds and currents different in direction and intensity at different locations. Furthermore, the previous search zone was based on two weeks of drift, while presumably the current zone is based on three weeks of drift.
SeenItAll is offline  
Old 28th Mar 2014, 22:11   #8558 (permalink)

 
Join Date: Jan 2008
Location: Australia - South of where I'd like to be !
Age: 53
Posts: 4,258
As I said a few days ago, I thought they'd fly in a helo on a C-17.

A specialist Seahawk


Here is some video and photos.

Missing Malaysia Airlines plane: Seahawk helicopter arrives at RAAF Pearce


500N is offline  
Old 28th Mar 2014, 22:24   #8559 (permalink)
 
Join Date: Jan 2008
Location: United Kingdom
Posts: 206
As a 777 pilot I, like many others, have wondered how the 777 would perform in the scenario where the pilots were incapacitated and the aircraft ran out of fuel. I had my ideas but there is nothing like seeing it for "real" so we tried this in a 777-2 full motion zero flight time approved simulator.

We used a zero fuel weight of 175 tonnes. We let it run out of fuel at FL 250 in track hold and alt capture. However it would not make any difference what mode it was in as everything would drop out. In real life one engine uses fractionally more fuel per hour than the other and there is typically a difference between main tanks of a few hundred kilos, so we had a 300 kg difference between the contents of the left and right tank.

When the first engine failed TAC (Thrust asymmetry compensation) automatically applied rudder. The speed reduced from 320 knots indicated to 245 knots indicated. It was able to maintain 245 knots and FL250. When the second engine failed the rudder trim applied by TAC was taken out and the trim went to zero. The autopilot dropped out and the flight controls reverted to direct mode. The speed initially came back to 230 knots but then the nose started to lower. The nose continued to lower and the rate of descent increased to 4,000 feet per minute, the nose kept lowering and the descent rate increased to 7,500 feet per minute with a bank angle that increased to 25 degrees. The speed at this point had increased to 340 knots indicated, above VMO but there was no horn as it was on limited electrics. About this point the RAT (Ram air turbine) chipped in and the CDUs and copilot's PFD (Primary flight display) came alive. The flight controls stayed in direct mode.The eicas screen was full of messages like pitot heat, flight controls, APU fault (The APU had tried to autostart due double engine failure but failed due no fuel to start it) low fuel pressure etc.

Then with a max descent rate of almost 8,000 feet per minute the nose started to slowly rise and keep rising. We had dropped to about FL170 but the nose slowly rose up to 6 degrees pitch up and we started climbing at about 3000 feet per minute and the bank angle reduced to only 5 degrees. It climbed back up to FL210 at which point the speed had come back to 220 knots and then the nose dropped down again and we were soon back to descending at 8000 feet per minute. So basically a series of phugoid oscillations with bank angle between 5 and 25 degrees and pitch attitude between about 9 degrees nose down and 6 degrees pitch up. It was losing about 8000 feet and then gaining about 3 or 4000 feet with airspeed fluctuating between 220 and 340 knots.

We didn't watch it all the way down due time constraints and stopped the experiment at 10,000 feet but it was consistent all the way down. Having watched it I can say with certainty that if the pilots were incapacitated and it ran out of fuel there is no way it could have landed on the water with anything like a survivable impact. Just passing on the info.
suninmyeyes is offline  
Old 28th Mar 2014, 22:36   #8560 (permalink)
 
Join Date: Mar 2014
Location: Pennsylvania, USA
Age: 54
Posts: 1
winds aloft

hamster3null - have you tried to factor in the winds aloft into your calculations? They seem to be considerable that night (and would of course affect the ground speed at each point). The problem with "crowd computing" is not having all the best information published.

This link was mentioned a while back and is the only place I've seen that attempts to show winds aloft at that time:

Investigation of a possible "southern arc" contrail from Malaysia Flight 370 - 8 March 2014 - Weather Graphics

If needed, I bet Tim Vasquez at Weather Graphics could get them for the altitudes and locations of interest.
balthasar63 is offline  
Closed Thread


Tags
acars, crash, elt, hf links, malaysian, mh370, missing, pingers, plane, vhf

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT. The time now is 06:08.


1996-2012 The Professional Pilots Rumour Network

SEO by vBSEO 3.6.1