MLAT aircraft stick on a chosen RX, but disappear on a merged feed.

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Joined: Mon Aug 22, 2016 8:35 am

MLAT aircraft stick on a chosen RX, but disappear on a merged feed.

Post by M1AXM » Wed Jan 11, 2017 10:36 am

Hi All,

I have a strange issue with a server with multiple feeds, the issue is this:

An example would be a chosen aircraft shows in the list as MLAT - YES and can be tracked on the map using the merged feed, but there comes a point where the chosen aircraft stops moving on the map and just stays stuck at their last known location - after a while they will disappear from the map when viewing the merged feed and are only shown on their last known receiver when selected (but are static), yet still show as MLAT - YES against said RX in the RS and merged feed list, with the message count still increasing.

It is odd, it seems a restart of VR seems to cure it momentarily, but this may be just masking the real issue.

The VR has about 38 feeders which are combined in the merged feed. I have had this issue on my home VR running with multiple feeds (4) too, the aircraft just disappear from the map, still visible in the list but are only visible - yet static when the allocated receiver is chosen from the receiver list.

Also - at times if you have the altitude on the aircraft label on the map - it changes but the aircraft does not move...

Has anyone else has and or seen this issue?

Many thanks


Posts: 2249
Joined: Fri Feb 17, 2012 3:20 am

Re: MLAT aircraft stick on a chosen RX, but disappear on a merged feed.

Post by agw » Sat Jan 14, 2017 3:15 pm

I think the "MLAT - YES" flag just indicates that the aircraft's position was supplied by an MLAT receiver. If the aircraft goes out of range of one of the 3 (or more) receivers that are being used to calculate MLAT positions then you'd get the effect you're describing.

When you see an aircraft stick on the merged feed is it still moving around if you switch to the MLAT feed?

The changing altitude on a non-moving aircraft just means that you're getting altitude messages from the aircraft but no position messages. Altitudes appear on a range of messages from the aircraft, they're not always transmitted along with the position.

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