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Air Asia Indonesia Lost Contact from Surabaya to Singapore

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Air Asia Indonesia Lost Contact from Surabaya to Singapore

Old 29th Dec 2014, 13:11
  #381 (permalink)  
 
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My MEL says I can't depart with WX RDR u/s if there is any wx that could be detected by radar enroute.

I have no problems flying without radar when the weather is good. I am in the business of transporting passengers from A to B, not finding ways to cancel the flight.
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Old 29th Dec 2014, 13:19
  #382 (permalink)  
fdr
 
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Device doesnt measure airspeed..

@cee cee...

There are aircraft that do not have pitot tubes...

I carry a nice little unit that displays g, attitude and flight path using a nice kalman filter, it is far better than the 100k i recently spent on an IFSD upgrade. Why do you need airspeed? With extraordinarily accurate att and fpv, i can generate airspeed if it makes you feel better, but tthe sircraft doesnt care, it only knows alpha and g loading. And until we as heavy jet pilots remember that we are going to repeat upsets.

Now for the subject topic of AAsias tragedy, how about letting the experts get on without the static that this forum generates with such ease. Sontoso et al are able to fibd and annalyse such an event with reasonable confidence, let them do their job, and let the families and airline grieve in respectful peace.
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Old 29th Dec 2014, 13:32
  #383 (permalink)  
 
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INS cannot give you airspeed and GPS does not help

GPS works really well in combination with an inertial navigation system to give your current position, speed etc. All of this ends up being rerenced to an earth based coordinate system via the GPS. This is very useful but not if you want the velocity of the aircraft relative to the air surrounding it. In this case you either need an independant measure of the air velocity relative to the ground and this in general seems totally impractical or you need to measure the speed with respect to the aircraft which brings you back to where you started. An INS is no use at all for measuring airspeed. It is perfect for measuring ground speed.

On why they do not use doppler to measure airspeed I am not an engineer working in this area but it may well be because you need to bounce a signal of a known frequency and velocity off something moving wth the air. I imagine there is not always anything there to bounce off. There are lots of ways of measuring gas velocity but I am sure the possible methods, their reliability, operating ranges, failure modes etc have been analysed extensively over the last 7 decades or so and what is used is used for good reasons.
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Old 29th Dec 2014, 13:34
  #384 (permalink)  
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you can bet that irrational or not, he IS comparing the mobile phone versus aircraft and is not impressed to learn that apparently the desired safety level comes at too high a cost. might not market forces drive a change before long?
It isn't a cost issue, as I already outlined. It is a political issue. Real time monitoring would require a new aviation band allocation. The international bun fight over allocation of available radio bands favours telecommunications companies seeking profits: Non-proifit, non-military use is pushed aside in the scramble.

As slats11 puts it:
Communication technology continues to evolve rapidly. What seems expensive or not practical or not justified on a cost:benefit analysis today may (probably will) soon become routine.

Even today there are handheld units that cost a few hundred $ (e.g. Spider tracks) that determine GPS location every minute and transmit it via Iridium at a few cents a message.
That says it all. Entertainment and other frivoluous use of the limited radio spectrum takes priority over aviation and we have lost so many frequency bands already: there just isn't an available channel for data telemetry - or any other additional aviation communications use.

Hell, we are beginning to have our airspace invaded by uncontrolled UAVs. [Yes they are just big-boys' toys, but still capable of bringing down an aircraft.]
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Old 29th Dec 2014, 13:35
  #385 (permalink)  
 
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Mahatma Kote,

This unit is derived from full scale INS so I ask the question why there is a problem on modern aircraft when pitot tubes and whatever are blocked / misreading?
With well trained and experienced pilots in the cockpit, there isn't a problem when pitot tubes are blocked. They know what to do, they understand attitude and thrust.

I understand there is a difference between actual air speed components and true ground-speed, but why is this high precision information source not used? Or if it is, why are things like pitot tubes more important and overriding the absolute measurements? Especially over extended period of seconds to minutes?
High precision ground speed from the 3 IRS's on board is one of the many tools a well trained and experienced pilot can use to determine which airspeed readings are erroneous and which are accurate. But not before securing the aircraft in a safe attitude and thrust setting for the conditions.

Problems arise when airline CEO's start believing that aircraft fly themselves (and indeed fix themselves), and do not believe having well-trained and experienced flight crew is necessary. This is what we call the "race to the bottom", and it doesn't only happen in Asia.

AF447 crashed because the pilots crashed it. I'm not speculating on this incident but merely answering your questions.
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Old 29th Dec 2014, 13:42
  #386 (permalink)  
 
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If a dispatcher presented me with a flight plan that had a course depicted like this one right through the centre of severe to extreme weather, I and no one I work with would dream of accepting it - so how was their flight plan created? Do they have a qualified flight dispatch department? If this is accurately portrayed why would the planners have thought it acceptable to file a course through an area of very heavy weather? Why should a pilot have to get airborne on a route that was clearly not going to work, and then have to start "negotiating"?
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Old 29th Dec 2014, 13:43
  #387 (permalink)  
 
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Originally Posted by Sallyann1234
continuous transmission of all FDR data from commercial aircraft would far exceed available satellite capacity. And extending that capacity to the extent required would be extremely expensive.
If each DFDR produced 100 parameters at 16 bit resolution at once per sec, that would be 200 bytes per sec per a/c. For 2,500 a/c, that would be 500 kilobytes/sec.

NASA's TDRS satellites are designed for receiving and forwarding telemetry, and have a total bandwidth of about about 1.1 gigabit/sec (137 megabytes/sec). Of this bandwidth handling all parameters from all DFDRs from all in-flight commercial a/c would take about 4% of TDRS capacity.

Obviously the primary use TDRS is for NASA but they accept other special users. I'm not saying continuous telemetry from all large commercial a/c is needed, nor that TDRS is the best way, but it illustrates the raw capacity is already there.
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Old 29th Dec 2014, 13:53
  #388 (permalink)  
 
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There is no substitute for airmanship and two experienced pilots upfront who have the healthiest respect for ITCZ weather.They steer well clear and they dont wait for ATC either(very often VHF will be temporarily lost due static and some guys want to keep the magenta line until they get clearance).
They must have flown very often to 'straya and got hollered at so badly by the very anal ybbb atc that they became psychologically damaged...hence the suicidal propensity to follow the magenta line into cb cells until they get the clearance to deviate!

Ybbb atc strikes great fear into Asian airline companies so much so pilots get severely punished for deviating without clearance!
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Old 29th Dec 2014, 13:55
  #389 (permalink)  
 
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Totem

In other words, it's 100% responsibility and no authority. Another gaping safety issue.

Now why does that not surprise me?!
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Old 29th Dec 2014, 13:58
  #390 (permalink)  
 
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Ybbb atc strikes great fear into Asian airline companies so much so pilots get severely punished for deviating without clearance!

that's when you make a PAN call and deviate as necessary...no clearance needed then...better than the other options yes?
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Old 29th Dec 2014, 14:00
  #391 (permalink)  
 
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but it illustrates the raw capacity is already there.
No, it really doesn't.

Do you buy an A380 and the leave it on the tarmac and just shout to the world that you've got capacity 400 people ?

No.

Well its the same with satellites.

Satellites cost a lot of money to build, get into space and monitor.

A satellite is in use 24 hours a day, 365 days a year as soon as the satellite reaches space, the operators will already be activating contracts ..... the cost of using satellite transmissions reflects the limited spare capacity available.

A satellite may well have a total transmission capability of X, but you can bet your bottom dollar that most of that capacity has been sold, if not even largely oversold on a contended basis ! The satellite operators would be out of business if that was not the case.

Satellite has always been and will always be more expensive than any form of ground communication, because of all the constraints the technology has, including the technology itself.... once its up there, you can't exactly turn up on site one day and upgrade the kit to newer stuff !

So please guys... ENOUGH of these stupid requests for realtime streaming data from all aircraft .... it just isn't workable. Period.
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Old 29th Dec 2014, 14:18
  #392 (permalink)  
 
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FYI

Civil Aeronautics Board
Aircraft Accident Report

Northwest Airlines, Inc.
Boeing 720B, N724US
Near Miami, Florida
February 12, 1963

http://upload.wikimedia.org/wikipedi...Flight_705.pdf

Synopsis

Northwest Airlines, Inc., Boeing 720B, N724US, operating as Flight 705, crashed in an unpopulated area of the Everglades National Park, 37 miles west-southwest of Miami International Airport at approximately 1350 e s.t , on February 12, 1963. All 35 passengers and the crew of eight were fatally injured

Flight 705 departed Miami at 1335 e.s.t. Circuitous routing was utilized during the climbout in an effort to avoid areas of anticipated turbulence associated with thunderstorm activity. At 1347 e.s.t , in response to a request for their position and altitude, the flight advised, "We're just out of seventeen five (17,500 feet) and stand by on the DME one." This was the last known transmission from the flight. Shortly thereafter the aircraft entered a steep dive, during which the design limits were exceeded and the aircraft disintegrated in flight.

The Board determines that the probable cause of this accident was the unfavorable interaction of severe vertical air drafts and large longitudinal control displacements resulting in a longitudinal upset from which a successful recovery was not made.

Last edited by airman1900; 29th Dec 2014 at 14:33. Reason: Error
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Old 29th Dec 2014, 14:27
  #394 (permalink)  
 
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Originally Posted by mixture
Satellites cost a lot of money to build, get into space and monitor....you can bet your bottom dollar that most of that capacity has been sold, if not even largely oversold on a contended basis !...
My previous post: http://www.pprune.org/rumours-news/5...ml#post8801005

Was talking about NASA TDRS (Tracking and Data Relay Satellites): Tracking and Data Relay Satellite System - Wikipedia, the free encyclopedia

They are already built and flying and mainly just used for telemetry from space launches. They have over 1 gigabit/sec of capacity, so they are vastly over-provisioned for the initial intended use. Consequently NASA sells bandwidth on these to other agencies, including non-governmental entities.

I'm not saying continuous telemetry from commercial DFDRs is needed, nor that TDRS is the best way even if it was needed. I'm just responding to the post that there's no available satellite bandwidth.
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Old 29th Dec 2014, 14:27
  #395 (permalink)  

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Relevance

If it was Commercial Pilots only contributing here, the thread would stay far more relevant (more or less!).

However it is open to all, so we will get subjected to lots of off-track contributions.(Insurance, telemetry, piracy to cite but 3!). To be fair, 99% of air accidents involve pilots directly, but there are the occasional ones such as the Ukraine shoot-down where the pilots will not have had a clue and were doing their job correctly. (Note I say "involve", not ascribing blame unilaterally)

Speculation can be good; however, as the national reports can take a long time to be issued and in some cases are worthless. And manufacturers need to react quickly if a technical issue crops up, in order to prevent further accidents long before waiting for the national report to be issued.

And officialdom can anyway be hopelessly wrong, or biased. Their "facts" can be as correct as a politician's. The Egyptair 767 mid-Atlantic suicide crash is widely seen as a case in point.
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Old 29th Dec 2014, 14:33
  #396 (permalink)  
 
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Debris

Slats 11:
You can't have it both ways however. Most scenarios which cause sudden loss of communications will cause lots of debris. Conversely, most scenarios that cause minimal debris imply control and hence communications should be maintained.

Sudden loss of all communications could be due to catastrophic structural failure which would cause lots of debris, or an AF447 like event which also caused fragmentation at impact and lots of floating debris. They found lots of debris fairly quickly (days) with AF447 - even though
i. the initial search was delayed by at least a day
ii. the search area was much larger (they didn't "see" loss of the transponder with 447)
iii. the search area was mid-ocean (severely complicating the search by limiting aircraft time on scene and delaying arrival of ships).
None of that applies here.

There simply are not that many explanations for sudden loss of all communications and no debris - especially in a small area.
January 1, 2007 Adam Air Flight KI-574, flying from Surabaya, on Java Island, to Manado, on Sulawesi Island, disappeared in bad weather with 102 people aboard. It took 10 days for any trace of wreckage to be found.
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Old 29th Dec 2014, 14:39
  #397 (permalink)  
 
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Perhaps the crew from that EK409 or AWQ504 flights can comment on the conditions experienced rather than the interpretation (or be it misinterpretation) of the data available....
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Old 29th Dec 2014, 14:44
  #398 (permalink)  
 
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They have over 1 gigabit/sec of capacity, so they are vastly over-provisioned for the initial intended use.
You're still ignoring the issue.

I don't give two hoots what someone's "provisioned capacity" is.

Even your beloved NASA TDRS doesn't have the SPARE capacity for live telemetry from all aircraft. So please, give it a rest !

Here, I'll even quote you a NASA 2014 report (IG-14-018) on the very subject, I have highlighted the key phrase :
The Agency retired two first-generation satellites (TDRSs 1 and 4) in 2009 and 2011, and the remaining four first-generation satellites still in orbit (TDRSs 3, 5, 6, and 7) are showing signs of age-related battery and electronics failures. NASA has predicted that without replacement satellites the Space Network will not have sufficient capacity to service customer missions adequately by 2016. Similarly, a 2013 Aerospace Corporation Study concluded that in order for the Space Network to continue to support anticipated communications, NASA may need to launch TDRS-M by 2016 and require an additional satellite in orbit by 2024.
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Old 29th Dec 2014, 15:03
  #399 (permalink)  
 
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Mcdunav: Should not the possibility of the plane crashing in the Belitung forests be considered?

Start with the known location of loss of comms. Take max possible a/c airspeed, and known fuel reserve to determine the furthest the aircraft could have flown from the LKP, and draw a circle of that radius centre on the LKP. In principle the a/c could have come down "anywhere" in that circle.

Now get as much information from primary radar as possible, and any other credible data source, and narrow down the area within that circle to give a starting area to concentrate the initial searches for the available search resource - if those initial searches fail then widen the search area. Resources are not infinite. Time is important but you have no control over how long the searches will take irrespective of the media clamour for "information". Make sure that you spend your time trying to get results and not wasted on chatting to the media....
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Old 29th Dec 2014, 15:16
  #400 (permalink)  
 
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Also, FL360 may not have been available to due crossing traffic ahead.
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