FlightAware Discussions

Why choose not to allow mlat

Why would someone choose not to participate in mlat?

As much of this ADS-B tracking is enthusiast driven it seems odd that someone might disable mlat.

Appreciate could be unintentional, also maybe portable units disable mlat but are there any other considerations I am not aware of?


Uses more CPU and traffic compared to feeding only ADS-B.

Also some people just never configure the location.

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Two other considerations;

  1. There are not enough other receivers around to participate. I believe at least 4 receivers need to see the plane at the same time. At some locations there are no other receivers within 500km.

  2. The cost of data. There are a number of receivers that use cell data to provide data to Flightaware. Turning on MLAT users about 4 or 5 times as much cell data and in a remote location may only add one or two MLAT planes a day and most likely they will be reported by other receivers with much cheaper data rates.



And in my case, I’m interested in the number of planes received, not seeing them plotted on a map necessarily.

Being in North America, more and more planes will be ADS-B capable. In fact, I think the number has already increased compared to 3 years ago. The FAA’s deadline is fast approaching for certain types of aircraft and flight plans.

I miss certain planes not doubt, but they were never of my interest to begin with.

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So do the mlat transmissions still get counted then? Dicnt realise that was the case.


The MLAT provides position. The plane is still counted even if positionless.


Indeed MLAT dropped a lot and ADS-B increased correspondingly. From MLAT being approx 1/2 of number ADS-B planes last year, now I am seeing only like less than 1/10. I am still synchronized with some 200 receivers.

FA’s stats list ADS-B and mlat separately for both positions and aircraft along with ‘other’ and the sum is totaled so I thought if mlat was disabled it would reduce daily statistic totals.


That describes one of my sites.
I enabled MLAT a few days ago (15/8), just to convince myself it’s not worth running (I do this a couple of times a year).
It’s currently Sync’d with 33 other sites. The 24th site (furthest shown on my Nearby Sites table) is 117NM.
Obviously at that distance, any aircraft seen by both sites will be high enough to mandate Mode-S.

For 4x the data volume, it seems a poor return.
The data is via cellular link, so the cost is significantly higher than traditional feeds.

I used to leave mlat off because I live out in the sticks and had satellite internet service. I was limited to 10GB per month. With mlat on, I would use about half of my 10GB of data uploading the mlat data. I see about ~320 mlat aircraft and about 30,000 mlat positions per day.


I get around 500 mlat aircraft daily, around 200 ‘other’ and about 1000 ADS-B. Am in London about 14 miles from Heathrow but also 3 miles from a local private airfield, maybe that is why so many mlat.

A also run a Piaware at a friend’s home in California, she is West Coast midway between San Diego and LA, she too is very close to a local municipal airport but only gets around 60 mlat per day but around 1000 ADS-B and 200 ‘other’.

My data is unlimited, her’s is a big allowance.