Not seeing planes land (Istanbul & Almería airports)

DarioM

New Member
Good morning all,
I had a family member on flight TK1980 LHR to IST yesterday; I saw the ADS-B beacon come on at startup at LHR and was able to track the flight all the way to Istanbul Airport …

However I noticed on approach, I was watching speed and height come down, it got to 257 knots, 363 metres then the icon for the flight continued at that exact height and speed along the centreline of the runway, and then onwards out to sea where the signal disappeared.

I reasoned that it was a glitch in the signal and that aircraft had obviously landed and switched its beacon off, but I tracked another 4 aircraft of differing types (all Turkish Airlines) into IST and they all did the exact same thing - got to a height of about 300 metres plus or minus and a speed of about 230 - 260 knots, then carried on along centreline of runway at the same speed and height before going past airport, out to sea and disappearing. I’ve just checked this again right now and I watched RO261 (TAROM Romania) do the exact same thing - get to 267 metres, 226 knots aaaaand … tracking stops at this point.

What causes this? I didn’t think it would be beacon coverage as I was able to track the plane as far as IST (that being said, the internal flight she took, TK2232, didn’t come up at all (but that could just be an aircraft without ADS-B)

I’ve noticed the exact same thing happen at my local airport (local being 80 km away from me!!) Almería (LEI) with Iberian airlines (others seem to show approach and landing correctly though)

Would be very interested to hear possible causes of this

EDIT: I also notice at IST that unlike LHR or even LEI there are absolutely no beacons showing on the ground at the airport - and it is a relatively busy airport)
 
Last edited:

Richard Lee

Member
I once watched a plane do a landing approach then just keep going out to sea, where it finally disappeared. I had the same question.

It's the AI. When a plane gets down really low, or too far away from an ADS-B receiver, that's feeding the software (that's feeding your display) the software sees the ADS-B signal is lost.
So, it will make the plane disappear off your display, or Predict where the plane should be, assuming it's still flying in the same flight pattern. Direction, speed etc. I guess some AI can't Predict a landing at the airport the plane was a approaching when LOS occurred.
 

DarioM

New Member
I once watched a plane do a landing approach then just keep going out to sea, where it finally disappeared. I had the same question.

It's the AI. When a plane gets down really low, or too far away from an ADS-B receiver, that's feeding the software (that's feeding your display) the software sees the ADS-B signal is lost.
So, it will make the plane disappear off your display, or Predict where the plane should be, assuming it's still flying in the same flight pattern. Direction, speed etc. I guess some AI can't Predict a landing at the airport the plane was a approaching when LOS occurred.
So it comes down to lack of ADS-B beacons in and around the area ... that WOULD explain why there are no aeroplanes showing on the ground at Istanbul and only a few tracked flights across Turkey

Whats the range of an ADS-B receiver then?
 

Richard Lee

Member
Whats the range of an ADS-B receiver then?

The range depends on the height of your antenna and miles from the airport. I can't see planes on the runway at Logan Boston airport, but I'm about 10 miles from Boston. But only a few miles from the airport in Bedford, so I can see planes on the Bedford runway.
Sometimes in the summer (like today), but mostly in the winter when the leaves are Not blocking 1090 MHz.
Remember, microwave propagation is pretty much line-of-sight. Like WiFi :)
PS: During the winter, (no leaves) I sometimes see planes up in Canada.
 

DarioM

New Member
The range depends on the height of your antenna and miles from the airport. I can't see planes on the runway at Logan Boston airport, but I'm about 10 miles from Boston. But only a few miles from the airport in Bedford, so I can see planes on the Bedford runway.
Sometimes in the summer (like today), but mostly in the winter when the leaves are Not blocking 1090 MHz.
Remember, microwave propagation is pretty much line-of-sight. Like WiFi :)
PS: During the winter, (no leaves) I sometimes see planes up in Canada.
Sadly I don't have an antennae - would be interested to know how to join the ADS-B hosting community though
 

Richard Lee

Member
If you live in an area that needs more coverage by Plane Finder and meet all the requirements, you should be able to host a receiver system.
A lot of people just track planes for fun with a cheap SDR and laptop, so they can go portable on road trips or hill-topping.

It's a lot like the SWL hobby. These days, I'm doing a Ham Radio version of SWLing with WSPR mode on shortwave ham bands.
It's a neat way to check out the ham band propagation conditions, to see how far you can hear, and be heard if you have a Ham License.
I use a 5 watt digital transceiver, http://qrp-labs.com/qdx.html so I can not only hear stations from all over, I can see if they can hear my beacon signal. (using a 40 foot wire antenna) It's very interesting to me.. Not so much to my wife.. ;)
iceland.jpg
 

DarioM

New Member
Aaaahhhhh yes. I LOVE Radio Communications, although sadly know little of the technicalities. I cut my teeth on 27 MHz CB (AM) in South Africa and then the UK (where it was still illegal). Learnt what I know about wavelengths, tuned antennae and VSWR there. Then a stint (10 years) in the military and and I learnt that higher frequencies have shorter wavelengths and beome "Microwaves"and these wee beasties require a waveguide, not an antennae. It was only later I learnt that the frequency of a Microwave oven and the frequency of WiFi routers is the same ... 2.4 GHz!!

So yes, very interested in radio etc ... but have no equipment and only a little knowledge
 

Richard Lee

Member
It sounds like you have a lot more experience than most people getting into this hobby.. When I was getting my Novice ham ticket in 1968, the Ham radio club was using little 100mw CB AM walkie talkies while installing coax from inside a building, up a 100 foot tower. That night, I talked to a CBer kid down in Texas, over 2,000 miles away with 100 milliwatts on 27 Mhz.
After the new HF antenna was installed, I got to speak to King Hussein of Jordan on 20 meters. That night sold me on Ham radio.

Those cheap SDR USB dongles work great and don't cost a lot. You can use a simple TV antenna and pick up ADS-B with line-of-sight planes.
If you are up on a hill, a USB SDR can easily hear signals 100 to 150 miles away..
 

DarioM

New Member
It sounds like you have a lot more experience than most people getting into this hobby.. When I was getting my Novice ham ticket in 1968, the Ham radio club was using little 100mw CB AM walkie talkies while installing coax from inside a building, up a 100 foot tower. That night, I talked to a CBer kid down in Texas, over 2,000 miles away with 100 milliwatts on 27 Mhz.
After the new HF antenna was installed, I got to speak to King Hussein of Jordan on 20 meters. That night sold me on Ham radio.

Those cheap SDR USB dongles work great and don't cost a lot. You can use a simple TV antenna and pick up ADS-B with line-of-sight planes.
If you are up on a hill, a USB SDR can easily hear signals 100 to 150 miles away..
Well I have access to a 10 metre satellite dish and I am on the top floor of an apartment block with a clear view of the sky .... so what do you really need to get started with this and more importantly, where do you get it from?
 
Top