FlightAware Discussions

Novice question about seemingly abrupt altitude change


#1

Hi, currently there are three airlines that offer direct flights between Sydney and Manila. My newfound curiosity sometimes prompts me to track their flights.

I can’t help but notice that one airline “often” (thrice in the last two weeks?) has seemingly abrupt (I am new to all of this, sorry for the term!) changes like this:

Are they purposely doing this to avoid turbulence and such or just a gap of some sort?


#2

Guessing that this is https://flightaware.com/live/flight/PAL214/history/20190106/1900Z/YSSY/RPLL

That’s an abrupt speed change, not an altitude change; but either way it’ll just be a data error. Looking at the tracklog it looks like a mis-sequenced position which produced an unlikely speed.


#3

Thank you! Really helps the somewhat anxious flyer in me :grin:


#4

This is the portion of the tracklog for that flight accessed by clicking on the View Track Log button in the bottom right of your picture.

It seems the data is in error.

Note the latitude is steadily decreasing as it heads North but that one line circled in Red shows it increasing or heading South. The heading changes from 318° to 139° and then back to 318° in one and a half minutes.

Also note that it is the second last report from that ADS-B receiver before it runs out of range.

The line with the anomaly at Mon 10:50:57 appears to have a data error.

I doubt an A330-300 would be able to turn 360° or 180° and back again in 90 seconds.

These single data element error pop up quite frequently.

S


#5

Yeah, that’s what I meant by a mis-sequenced position - it’s likely that those two positions are in the wrong time order. In this particular case the receiver in question is a Planeplotter feeder, they are particularly susceptible to this problem if there’s no nearby piaware-based coverage available (we try to filter out the problem cases, but it’s not perfect)