Originally Posted by
Big Eric
This sounds more like the Loganair SF340 (I can't remember which one it is) that has a wonky transponder for use on tracking sites and usually just it's flight number shows, but they all disappear from tracking sites once they're under around FL30, much like the E145s do.
Well it's true that a Loganair SF34 (G-LGNA) departed SYY just before the E145.
But it headed SW (LM155 to Benbecula), not SE as described by the OP, so it doesn't sound like the same aircraft.