Calculation of 'maximum distance' in user stats

[petercr]

Is there a minimum tracking time or number of hits/positions reported for a distance to be reported? As well as FR24, I have VRS running and it regularly reports planes in excess of 200nm distant that FR24 doesn't.

As an example, last night I was watching a flight from Auckland to Chengdu and VRS reported that for at least 5mins it was tracking around 205nm away and yet my FR24 stats say the max distance seen was 197nm.

Just interested to find out...

[Oblivian]

There's filtering requirements for data. But none knows it.

Vrs will always hold onto patchy signal longer when fr24 likely drops it.

Sent from my XT1092 using Tapatalk

[mem0tap]

Out of interest, with the best set up possible I am only able to get a max distance of around 170nm. I see in stats that others have ranges of around 350nm? - how can this be when a plane travelling at 40kft can only be seen up to 250 miles away? - it suggests either there is something wrong with the calculation, false echoes are received or the indicated location of the receiver is NOT accurate or maybe the world is flat?- anybody with a range of this magnitude care to explain, your receiver's height above sealevel?

[Anmer]

how can this be when a plane travelling at 40kft can only be seen up to 250 miles away?

Not always. I am at 400 feet ASL, overlooking the sea to the south. I can "see" aircraft at FL380 at a distance of 270NM.

Put a receiver atop Mount Teide and distances of 350NM are easily possible.

[petercr]

A bit different to 100ft ASL in the middle of suburbia with trees all around...

And within 20km of BNE airport which runs 01/19.

[mem0tap]

THe curvature of the earth suggests that for an aircraft to be seen on the horizon at 350 miles distant it would need to be at a height of 80,000 feet, if it is flying at 40K then the observer would need to be at 40k - simple geometry, Of course signal 'hopping' is always possible BUT there are so many reporting at 350 miles I doubt it is due to atmospherics. I have taken a high gain omni, filter and pre-amp set up to height of 800ft with a perfect all round panorama and still only achieved just over 250 miles. - From mount Teide a plane flying at 40K would still only be seen at some 270 miles. I' jsut like to know how to receive LOS signals from over the horizon.

[Anmer]

THe curvature of the earth suggests that for an aircraft to be seen on the horizon at 350 miles distant it would need to be at a height of 80,000 feet

It depends on the height of the receiver/antenna installation and if there are obstacles between it and the aircraft in line of sight.

From mount Teide a plane flying at 40K would still only be seen at some 270 miles

I don't agree. My Mount Teide example is valid. As are my own recorded results. Here's an example taken just a few minutes ago. DLH542, FL310, 277NM away. Cross checked with FR24.

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This site may help:

http://members.home.nl/7seas/radcalc.htm