Why Outbound flights have longer range than Inbound flights ?

[Birdie]

Why Outbound flights have longer range than Inbound flights before it is handed over to the next radar ?

I noticed this.

[fungus]

Why Outbound flights have longer range than Inbound flights before it is handed over to the next radar ?

I noticed this.

Birdie,
It may simply be due to the fact that on approach an aircraft is lower since it is following a 3 degree glideslope. On departure they track much higher due to climbing at an angle exceeding 3 degrees. It could also simply be due to the location and/or the setup of a particular radar..... or a combination of all of the above.

Regards,
Gregg

[Birdie]

Birdie,
It may simply be due to the fact that on approach an aircraft is lower since it is following a 3 degree glideslope. On departure they track much higher due to climbing at an angle exceeding 3 degrees. It could also simply be due to the location and/or the setup of a particular radar..... or a combination of all of the above.

Regards,
Gregg

At between 30,000 - 40,000 feet .

[fungus]

At between 30,000 - 40,000 feet .

Birdie,
I'll just expand on one of the points I made above so that it might be a tad clearer. That will simply be a matter of the location of the radars, the direction of travel of the aircraft and the terrain. From my understanding of the FR24 software, if an aircraft on a particular radar doesnt lose the signal he will 'hang on' to it for a long period where as if the aircraft is heading in the opposite direction and 'held' by another radar he has to wait for that radar to lose contact before picking it up. It happens all the time here in Sydney with all the radars we now have in the area. My own radar has quite a few obstructions due to gum trees and hills/ mountains/buildings so that affect is quite noticeable. Sometimes I wont even display an aircraft on the map flying directly overhead if it has a strong signal from another radar and vice versa, I can be displaying an aircraft on the map over locations (sometimes hundreds of kilometres away) where there is another radar (or radars) if he has a blind spot or I already have a good 'hold' on the aircraft. The software at the server will keep displaying an aircraft until it is lost by that radar and is picked up by another. If it isnt, it will 'disappear' until it is.
It's also possible in some areas to see multiple rapid changes of radar if the signal from a number of radars is patchy in certain directions and/or locations.
Regards,
Gregg

[Birdie]

Thanks for that clear, detail explanation.

[vu2pmc]

Hi,

I have just started feeding data using the supplied Mode S rx. by virtue of being a hamradio operator, I do monitor ATC freq using my icom 7000 on AM bands. I have realised that when an aircraft initiates a VHF AM contact with oceanic control after change over from HF/ CPDLC, I can copy them on my radio, but it still will not show up on the flightradar24.com map for atleast two or three more minutes. My VHF collinear vertical antenna is tuned for 145 MHz and not for 118-136 Mhz band and my Mode S antenna and VHF collinear are hardly three meters apart on the same screen.
Any thoughts?

[fungus]

Hi,

I have just started feeding data using the supplied Mode S rx. by virtue of being a hamradio operator, I do monitor ATC freq using my icom 7000 on AM bands. I have realised that when an aircraft initiates a VHF AM contact with oceanic control after change over from HF/ CPDLC, I can copy them on my radio, but it still will not show up on the flightradar24.com map for atleast two or three more minutes. My VHF collinear vertical antenna is tuned for 145 MHz and not for 118-136 Mhz band and my Mode S antenna and VHF collinear are hardly three meters apart on the same screen.
Any thoughts?

ATC comms has nothing to do with when an aircraft will display on the map. There's only a minimal delay between an aircraft being picked up by our receivers, uploaded and displaying on the map. i can see an aircraft approaching on my receiver, then the map and it's flying overhead almost immediately. From memory (and I'll stand corrected) it's something like 15 seconds or so delay which is almost imperceptible.

Regards,
Gregg

[vu2pmc]

ATC comms has nothing to do with when an aircraft will display on the map. There's only a minimal delay between an aircraft being picked up by our receivers, uploaded and displaying on the map. i can see an aircraft approaching on my receiver, then the map and it's flying overhead almost immediately. From memory (and I'll stand corrected) it's something like 15 seconds or so delay which is almost imperceptible.

Regards,
Gregg

Thanks indeed. I am aware that ATC comms has nothing to do with map display. May be the Mode S Rx is picking up the signals from Aircraft, but there might be a delay to get it fed from the Rx to the server and then have it rendered on the map on the webpage. Never a complaint, just giving feedbacks.
On that note, can I ask you another doubt? What is the typical range for this Mode S Rx? I have the antenna installed on a 6 Meter GI pipe with no obstruction for atleast 10 mtrs in radius on my two storied terrace floor. Ant height must be approx 60 ft above MSL, and I am hardly 3 kms away from the coast line.