Hello to everyone and a question.

[Electra]

This is my first post and would like to say hello to everyone and thank those who feed to the site. 

I have a question that I searched on and found an answer from 2005.  The question is how long is the delay of the audio from the airport to my computer?  In other words, when a plane is given permission to take off, how long after that do I hear it?

I never thought about it before, but today was different.  My son is returning home from CYUL (Montreal) today so I brought up YUL Tower feed and listened.  In another browser tab, I had up flightradar24.com.  As I heard the tower give the cleared for take off instruction, flightradar24 showed the aircraft 25 miles south, climbing and accelerating.   Any thoughts or explanations? 

Thanks in advance.

[dave]

This is a good question.  There are a number of factors that contribute to audio delay on a stream:

- Capture buffer (<500ms)
- Encoding buffer (~250ms-1s depending on codec)
- Encoder-to-Server Network Transfer and Buffer (<10ms)
- Server buffer
- Server-to-Client Network Transfer and Buffer (<10ms-1s typically, longer times for mobile)
- Client buffer (widely variable, but 2s is typical)
- Client playback buffer (<500ms)

What sort of delay are you actually seeing?  On most feeds where I can measure it we see just a few seconds total delay.

-Dave

[AeroBill]

Just did a check on CYUL tower and a real time flight24 (plane in yellow) taking off. CYUL was a maybe a minute earlier than
Fight24 showing it taking off.  I have observed that LiveATC is just a few seconds delayed, as Dave says, from the real time
broadcast if you are listening on a scanner.
My guest would be what you observed had more to do with Fight24 and how it tracked the plane, than LiveATC. Note too, that
on Flight24 planes in orange show a 5-minute time delay.

[J-LucB]

I can hear my own feed going to and coming back from USA (from France) while listening "live". The delay is between 5 and 10s.