rankamateur Posted May 10, 2014 Posted May 10, 2014 What makes a plane disappear off the screen? Tonight I was following Jetstar 672 Sydney to Darwin and at 10.16 (12.16 UTC)it just diappeared about Bourke. Any Clues?
rankamateur Posted May 10, 2014 Author Posted May 10, 2014 It came back on at 10.40 (12.40 UTC), it's OK I can breathe again now. Don't like people turning off their transponders, gives me a spooky feeling when I am tracking my family!
01rmb Posted May 10, 2014 Posted May 10, 2014 Below is the ADSB coverage map at 30,000 from Air Services. The red area is primary radar coverage and the purple is the ADSB coverage. I would assume the aircraft 'dropped off' the screen when it left the radar coverage area near Bourke. http://www.airservicesaustralia.com/projects/ads-b/
Exadios Posted May 10, 2014 Posted May 10, 2014 A better question is to ask, "What makes a plane appear on FR24?" The answer to that question is either a base station is receiving ADSB 1090S from the plane or three base stations are receiving the Mode S transponder replies. In the absence of either of these conditions the plane does not appear - i.e. disappears. 1
Exadios Posted May 10, 2014 Posted May 10, 2014 Below is the ADSB coverage map at 30,000 from Air Services. The red area is primary radar coverage and the purple is the ADSB coverage. I would assume the aircraft 'dropped off' the screen when it left the radar coverage area near Bourke.http://www.airservicesaustralia.com/projects/ads-b/ That is not the FR24 receiver map. That is a map of the ADSB station operated by Air Services (who do not feed data to FR24). 1
rankamateur Posted May 10, 2014 Author Posted May 10, 2014 MAS140 is at the same point on the same flight path right now, will be interesting to se if they have 25 minutes off too.
rankamateur Posted May 10, 2014 Author Posted May 10, 2014 While I typed that they disappeared at the same spot!
Mriya Posted May 10, 2014 Posted May 10, 2014 Exadios is on the money. FR24 is a private network of ADS-B recievers that are linked by the net to the FR24 server. Their coverage is dependant on enthusiasts being willing to set up receivers and leave them on, providing a web feed. Gaps in FR24 coverage occur when no private receivers are active in a given geographical area. The coverage map listed earlier relates to the official Airservices Australia network which has been designed to give complete coverage for ATC purposes, however FR24 doesn't access this data.
Head in the clouds Posted May 10, 2014 Posted May 10, 2014 It came back on at 10.40 (12.40 UTC), it's OK I can breathe again now. Don't like people turning off their transponders, gives me a spooky feeling when I am tracking my family! I sympathise Rank. And I'm sure Exadios and Mriya are right about the private network but for some reason it's not even quite as simple as that because some planes disappear and others don't. I got a huge fright last year, my wife was returning from Europe and had just departed Abu Dhabi for Melbourne. Her flight seemed to be late departing then popped up on R24 already about 30mins south of AD. I watched her flight and a couple of dozen others for a few minutes and then was about to go back to bed when her flight just disappeared but all the others carried on as normal. In fact there was a stream of flights heading for East Africa, India etc. I kept watching and getting just a little concerned but her flight didn't re-appear. Eventually I assumed transponder failure or 'something' and went to bed but set an alarm for an hour later to check that it had re-appeared. I was a bit bleary when I woke so I turned on the TV in the lounge and went to the computer in the office. My wife's flight still wasn't showing but all those that left around the same time were bright as day. So I did start to get rather more worried and a couple of minutes later came as close to having a heart attack as I ever have. I heard the TV announcing the crash of an airliner and rushed into the lounge to see vision of a jet slamming into the ground, skidding along and partially breaking up. Of course I just assumed the worst and started to think about survival chances and all that, at least it hadn't burnt and the wreckage wasn't mangled, there was a good chance she was OK. What I didn't take into account in the moment of 'panic' was how did someone get footage of this crash way out in the desert? It was July 6th last year when the Asiana 777 crashed while landing at San Francisco. Once I realised that it was a case of mixed emotions of relief for me and deepest sympathy for those who would really be experiencing the shock. For some undiscovered reason my wife's flight didn't come back onto R24 at all until it was over Spencer Gulf near Adelaide ... but it was very interesting switching to the cockpit view to watch the last half hour including the 'circuit', approach and landing into Melbourne. 1 1
Admin Posted May 10, 2014 Posted May 10, 2014 Did you know that flight radar 24 is included under pilot tools here on Recreational Flying
rankamateur Posted May 10, 2014 Author Posted May 10, 2014 My Daughter landed safely in Darwin early this morning. She flew from Melbourne to Auckland ten days ago and that flight never showed on FR24. It is just a toy for our entertainment, not a reliable source of information.
Admin Posted May 10, 2014 Posted May 10, 2014 I found it handy to watch the search aircraft when an aircraft is down 1 1
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