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  • Mike(nzradar.com) has told us that he has gone as far as he can with adsb and has just lost the interest he had at the start. Maybe he just wants to play golf instead or learn to fly. He has certainly been a great help for me when I got started. I wish him luck in whatever he takes up in the future.
    No doubt, in time, someone will fill in the gap left by his departure.

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    • This may be a question for the Virtual Radar forum but I thought I might try here first. Does anyone know where or how to apply altitude correction for pressure changes within VR? I am assuming that the altitude I am seeing displayed in VR is "raw" data from the aircraft, the reason I ask is that with the big high currently over NZ aircraft landing at WN are showing around -450ft on landing - yet strangely they look to be at the correct altitudes in cruise. Is this tied up with the standard pressures and transition layers etc?

      many thanks in advance for the expert opinions

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      • Its meant to be the pilots punching it in an adjustment when they are on approach when contacting tower and hearing 'Wellington QNH 1027

        And by golly, you weren't kidding. My station has 1030 on it at present. Bit to beat the 1035 max in July.
        Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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        • Originally posted by Oblivian View Post
          Its meant to be the pilots punching it in an adjustment when they are on approach when contacting tower and hearing 'Wellington QNH 1027

          And by golly, you weren't kidding. My station has 1030 on it at present. Bit to beat the 1035 max in July.
          Yeah, the pilots are making adjustments, but not to the altitude transmitted by the transponder. The transponder is always transmitting altitude according to the ISA (International Standard Atmosphere) pressure of 1013 Hectopascal at sea level.

          The pilot will adjust their altimeters (the altimeter is in fact a pressure measuring device) depending on the actual local pressure, and/or the flight level they are meant to maintain.

          Above the Transition Level (TL)/Transition Altitude (TA) flights are conducted at flight levels (FL) and at pressure setting 1013 (ISA) regardless of the local pressure. This way all traffic will fly at the same levels e.g. FL 330 or FL 340 even over greater distances.

          Below the TL/TA the pilots adjust the altimeter to the local pressure (QNH) which they will get from the Air Traffic Controller (ATC).

          The idea is that in the cruise everybody should be at the same levels relatively to each other, but during takeoff/departure and approach/landing you should be at the correct altitude relative to the terrain.

          The TA will vary from location to location depending on traffic density and terrain heights. In New Zealand the TA is a 13.000 feet for the whole country. In other countries it may vary from region to region.

          This means that at lower altitudes the altimeters may be set to a different pressure than the standard 1013 used by the transponder. ATC will adjust the readout from the transponders to the local QNH for traffic below the TL/TA to get a correct altitude on radar screens, but FR24 does not do this, therefore the discrepancy and landings at minus something when the pressure is high.

          One hectopascal is equivalent to 27 feet, so at QNH 1030 the display would be out by 460 feet. So it all adds up to what you have seen.
          Kpin – pilot of sorts (let me know if I’m boring you)

          PS: I do not know what you can do about that in VR

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          • Kpin, thanks for that - all of which I understood due to also being a pilot of sorts (a dusty PPL and a bunch of CPL exams passed too many years back). So no, not in the least boring.
            I thought it might be the ISA height I was seeing, I'll pop a message onto the VR forum and see if there is a correction method available.

            Does PP have the same 'issue' or is it a bit smarter?

            Cheers
            Colin

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            • I generally see the same thing. But you can set it up to recognise local airport pressure METAR and list the transition level, so it may make for compensations
              Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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              • Check the nZ plots.. we got A380s and 777s with nowhere to go with AKL closed!
                Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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                • Originally posted by 41south View Post

                  Does PP have the same 'issue' or is it a bit smarter?

                  Cheers
                  Colin
                  In PP chart options you can click QNH manually but it only lasts as long as the current map is open (click again for each map change).
                  Cheers, Dom. (YSSY7)

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                  • Originally posted by Oblivian View Post
                    Check the nZ plots.. we got A380s and 777s with nowhere to go with AKL closed!
                    A nice surprise to have a gaggle of Emirates aircraft passing overhead, including two A380's that we never see down here outside of this kind of situation.
                    Last edited by FlatEarth; 2013-07-30, 01:35.

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                    • Have our northern brothers seen the Nasa SP today? I had 2 hits at 3am where it then went offline, and we were fogged out last night/this morning. Their flightaware track stops abruptly near the cook straight.

                      And its not on its park this morning. After a 9hr mission I doubt they are heading home already? due out Aug2

                      If anyones near WLG airport might pay to check in
                      Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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                      • Originally posted by Petenz View Post
                        Mike(nzradar.com) has told us that he has gone as far as he can with adsb and has just lost the interest he had at the start. Maybe he just wants to play golf instead or learn to fly. He has certainly been a great help for me when I got started. I wish him luck in whatever he takes up in the future.
                        No doubt, in time, someone will fill in the gap left by his departure.
                        It's a little sad when someone who's radar is actually making a difference to the FR24 cover chooses to leave - perhaps Mike would be willing to host one of the boxes FR24 sends out that needs no expertise or day-to-day attention once installed.
                        Last edited by peterhr; 2013-07-31, 07:10.

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                        • Flight Aware has the Nasa747 leaving CHC going to PHIK?

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                          • Correct. Last deployment flight was on Tue/Wed. Now heading back home via Hickman AFB Hawaii (they refuel and possibly pickup extras as they use govt/mil AC for passengers out of there)
                            Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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                            • Originally posted by dayg View Post
                              Flight Aware has the Nasa747 leaving CHC going to PHIK?
                              Just noticed that its in my aircraft list at the moment, cruising at FL350

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                              • T-NZNS1 seen again. Nice
                                T-NZNS1.JPG

                                BTW is it normal for a flight to Perth to take a route this much to the south?

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