PPRuNe Forums - View Single Post - Jet goes down on its way to Medellin, Colombia
Old 3rd Dec 2016, 00:46
  #529 (permalink)  
Join Date: Jun 2001
Location: Rockytop, Tennessee, USA
Posts: 5,292
Originally Posted by DaveReidUK View Post
The remaining RJ85s that CityJet didn't sell to LAMIA regularly fly around the UK sending an ADS-B NUCp of 0.
Were the RJ85's one of the early planes to get ADS-B installed perhaps?

Here's a 2012 post from an FR24 admin that mentions an 'old transponder' with a 'calculated position' instead of GPS in the RJ100:

There can be several issues behind incorrect positions.

* Map calibration error
* Transponder error (sending wrong or random data)
* Receiver error (some kind of error in receiving so numbers get incorrect)
* Database error (some kind of mix up in database)
* Old transponder (some aircraft like RJ100 don't have GPS position but calculated position. It works OK on take off from Gothenburg, but once they reach Stockholm they land up to 30 km off from Bromma airport).
Why is the position of the plane sometimes wrong?

Originally Posted by DaveReidUK View Post
That's supported by the fact that the coordinates sent as it turned onto the runway at Viru Viru were offset by approximately 1 nm SSE, so it's likely that at least that much error will apply to the subsequent ADS-B track.
The error looks like much less than a mile to me. At any rate, the holding pattern does not seem to be plotted at the VOR but several miles south. But it appears to be very close to the extended centerline of the runway.

Perhaps coincidental but as many have observed, the plane sure hit close to the VOR.
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