Aircfraft Way off

[planes0001]

Noticed quite a lot with City jet aircraft (screen shot below) and with some other aircraft that they apear way of the extended centre line of the runway. Has anyone else noticed this with  city jet aircraft?

[RodBearden]

Hi Planes0001 - this has been reported many times, and is a constant problem caused by inertial navigation system (INS) drift - the position goes off as a flight progresses. You won't see it on aircraft equipped with GPS, just older ones with INS.

Near me, Jet2 B733's constantly miss Blackpool Airport runway, but Ryanair B738's get it spot on! It's not RB's fault - it just shows what the aircraft broadcasts. When everyone gets GPS, the problem will disappear. As long as the pilots don't rely on the INS for landing, its not too much of a problem for them.

Rod

[Fenris]

Noticed quite a lot with City jet aircraft (screen shot below) and with some other aircraft that they apear way of the extended centre line of the runway. Has anyone else noticed this with  city jet aircraft?

It's not unusual with older aircraft that don't use GPS-based nav kit.

Essentially the navigator can't get enough star-shots quickly enough to allow him to calculate a small enough cocked-hat so that the transponder is fed with accurate data.