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  • #16
    It is still early days, and this is by no means the exact reason why AAR214 crashed but it is an interesting article attempting to explain what happened.



    and yes indeed, let's leave the investigating to the experts and NTSB.

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    • #17
      Originally posted by North Borneo Radar View Post
      It is still early days, and this is by no means the exact reason why AAR214 crashed but it is an interesting article attempting to explain what happened.

      and yes indeed, let's leave the investigating to the experts and NTSB.
      Thanks NBR,

      That's a brilliant piece of work although I'm in no position to argue it's validity. I'll only make a few comments which on the whole arent actually to do with the accident itself. The author/authors make mention of PRM approaches being available for the landing runway. "They could have used GPS for vertical guidance (there is an RNAV (GPS) PRM RWY 28L approach), but may not have done so". PRM approaches are only available (and approved) where pilots have been trained and accredited, aircraft are so equipped, capable and approved, ATC are trained and approved and an airport is capable and approved for such operations. Pilots are advised by the Airport ATIS on the particular comms radio frequency (which they MUST listen to and acknowledge receipt of) on approach if they are in use and must advise ATC if they are (or arent) 'PRM enabled.' Then the weather comes into it. Whether it was available (or necessary) in this case isnt clear or perhaps it's better to say we cant comment on as the weather (again stated by the author/authors) would only seem to indicate (as does the vid in my post above) that it may not have been required. The following explains something of how these approaches apply here (in Australia);



      Whether it would have made one iota of difference in this case is also probably arguable. Whether it was necessary to use is debatable. PRM approaches are a precicion ILS approach carried out in inclement weather conditions and are carried out at Sydney Airport at times making for interesting viewing on the radar/map. An interesting paragraph in this article from Air Services Australia could be said to apply equally to all approaches;

      "A thorough cockpit briefing between crew members well in advance of commencing the approach is an essential part of an ILS PRM approach. All flight crew members must be thoroughly familiar with the approach, the procedures required for the aircraft they are flying and most importantly, the procedures to be followed in the event of a breakout." For 'an ILS PRM' substitute 'any' and for 'breakout' one could equally substitute 'go-around.'

      Food for thought while we wait for the investigation outcome. Please note that I'm not making any pre-conceived assertions as to whether the accident was caused by weather, aircraft, pilot, airline, ATC, procedures in general or all or any of the above. That will come in the fullness of time from the appropriate authorities.

      Having regard though for all the above (and more not covered here) I have the utmost respect for every pilot (and that has to be the absolute vast majority of them mercifully for us) who can climb into the cockpit of an aircraft and take-off, and then land it safely.

      Regards,
      Gregg
      Last edited by fungus; 2013-07-08, 21:12.
      YSSY2/T-YSSY4 [SBS-1 Basestation w/- SSE-1090 SJ Mk2 Antenna (Thanks Delcomp) ] [Uniden UBCD996T w/- 16 element Wideband Discone VHF/UHF Antenna, and tuned 108MHz-137MHz Airband Antenna] [Trialing a home-brew 1090MHz collinear antenna]

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      • #18
        Flightradar24.com -

        We have analyzed the last 150 seconds of data from flight ‎#OZ214. It looks like the ADS-B transponder continued to transmit data for about 10 seconds after the first impact. You can also see that the altitude increased after the first impact, when the aircraft bounced up in the air. The ground speed in the last seconds of the flight was only 112 knots.

        You can download the Flightradar24 Google Earth kml-file if you want to see the last 150 seconds of flight in Google Earth http://ge.tt/45Z3VGl/v/0?c

        or

        Showing on Google Map with the same file above.


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        Last edited by SoCalBrian; 2013-07-09, 00:33.
        Brian

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        • #19
          Originally posted by SoCalBrian View Post
          Flightradar24.com -

          We have analyzed the last 150 seconds of data from flight ‎#OZ214. It looks like the ADS-B transponder continued to transmit data for about 10 seconds after the first impact. You can also see that the altitude increased after the first impact, when the aircraft bounced up in the air. The ground speed in the last seconds of the flight was only 112 knots.
          Brian,

          Interesting plot and thanks. However we may have to be cautious about using this altitude data if it comes from our receivers (or perhaps more accurately in this case the aircraft ADS-B transponder) as ADS-B was initially designed in order to allow aircraft to maintain separation from each other outside of the range of primary and secondary surveillance radar and to do so at closer spacings. My understanding (and I'll stand corrected on this) is that as such the altitude data (to other aircraft and to our receivers) is fed via an altitude encoder to make certain that all aircraft in a given area, irrespective of the settings on their altimeters, are able to transmit the same altitude from their ADS-B transponder as all other aircraft in the vicinity at a standard pressure of 1013.2 mb. Therefore they are able to maintain separation at the same altitude (all transponders are thence 'talking the same language'). Most modern airliners are equipped with 3 altimeters (including the standby) so it would be troublesome in the extreme if they were trying to maintain separation with their altimeters possibly on different settings in relation to another aircraft. Once within range of the Primary or Secondary radar this becomes basically irrelevent as all altitude changes and settings are done by using the area QNH and the QNH of the airport by the pilots in conjunction with the guidance of ATC when being vectored to the airport or following standard SIDs/STARs.

          In a nutshell what I'm saying is that the altitudes fed to us from the aircraft relate to 1013.2 mb, not the prevailing QNH so there may be some slight discrepancy (hence I recently had an aircraft on my radar land at YSRI RIC RAAF Richmind NSW displaying -125ft when the elevation of the airport is 70ft). I'd be interested in feedback on this one if for no other reason than my understanding of this aspect of the technology is incorrect.

          Regards,
          Gregg
          Last edited by fungus; 2013-07-13, 14:32.
          YSSY2/T-YSSY4 [SBS-1 Basestation w/- SSE-1090 SJ Mk2 Antenna (Thanks Delcomp) ] [Uniden UBCD996T w/- 16 element Wideband Discone VHF/UHF Antenna, and tuned 108MHz-137MHz Airband Antenna] [Trialing a home-brew 1090MHz collinear antenna]

          Comment


          • #20
            Aircraft (and Runway) Headings

            In addition to the information in my previous post relating to altitude and altitude encoders which has been spawned by the very comprehensive reports done on the Asiana crash, I've also noted over a very long time period that an aircraft heading doesnt match the heading given to the pilots by ATC. (I'm listening to the aircraft on a scanner as well as following it on FR24 map and my 'Radar' receiver, both of which do indicate the same heading). I'm currently watching an aircraft on approach to SYD (QFA557) that was given a heading of 180* (degrees) to follow by ATC but it's track maintained a heading of 191.1* (degrees) during this time. For any skeptics the aircraft followed this heading for some time so it had every opportunity to turn to 180* (degrees). Does Magnetic Variation explain this phenomenon? Here in Sydney the Magnetic Variation is approx. 12* (degrees) which at face value would seem to explain this discepency. It would appear that our receivers (and hence the map) arent capable of taking Magnetic Variation into account. Also apologies as my laptop doest have a readily accessible degrees key.

            For anyone wondering what Magnetic Variation is; http://en.wikipedia.org/wiki/Magnetic_declination

            On a slightly different topic there is also an interesting clue in this article as to why we regularly see the calibration aircraft in many countries on the map and also where airport runways get their designation and why they sometimes require adjusting;

            "Radionavigation aids located on the ground, such as VORs, are also checked and updated to keep them aligned with magnetic north to allow pilots to use their magnetic compasses for accurate and reliable in-plane navigation."

            "Runways are named by a number between 01 and 36, which is generally one tenth of the magnetic azimuth of the runway's heading: a runway numbered 09 points east (90°), runway 18 is south (180°), runway 27 points west (270°) and runway 36 points to the north (360° rather than 0°). However, due to magnetic declination, changes in runway names have to occur at times to keep their name in line with the runway's magnetic heading. An exception is made for runways which lie within the Northern Domestic Airspace of Canada; these are numbered relative to true north because proximity to the magnetic North Pole makes the magnetic declination large."

            It seems to me that it (Magnetic Variation) has a similar explanation as to why the Transition Altitude ((where the altitude is expressed in feet (or metres) as against a flight level)) cant be shown on the map as it isnt equal all across the world. Therefore you see some strange figures on the map at lower altitudes.

            Transition Altitude;



            Again any comments would be most welcome.
            Enough brain strain for one night.
            Regards,
            Gregg
            Last edited by fungus; 2013-07-13, 12:57.
            YSSY2/T-YSSY4 [SBS-1 Basestation w/- SSE-1090 SJ Mk2 Antenna (Thanks Delcomp) ] [Uniden UBCD996T w/- 16 element Wideband Discone VHF/UHF Antenna, and tuned 108MHz-137MHz Airband Antenna] [Trialing a home-brew 1090MHz collinear antenna]

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