Last seen 44 years ago


#1

Last Seen: 31-Dec-1969 - 44 years ago
Joined: 22-Nov-2014
Longest Streak: 10 days (23-Nov-2014 - 02-Dec-2014)
Feeder Type: PiAware (SD Card) 1.18
Nearest Airport: Westfield-Barnes Rgnl (Westfield/Springfield, MA) (KBAF) - United States

Strange date last seen / this info was from 02 Dec 2014 01:30Z … I had restarted the fadump1090 after changing some dump1090 parameters …


#2

mentalfloss.com/article/26316/wh … er-31-1969


#3

While I stopped and restarted the fadump1090 software the Pi was not rebooted - so I would assume that the software clock was still ticking away and hadn’t reset its time in any fashion. (If I have time later I’ll try to repro.)

My question / concern was whether the piaware software actually sent some bogus time to the FA ADS-B ingest …

Later the 44 years changed - I’m assuming with a valid report being received.


#4

You’ve found a bug, obviously. It’s kind of interesting. 44 years ago is the start of UNIX system time, also known as the epoch… 00:00 GMT on January 1st, 1970. Time is kept in UNIX (BSD, Linux, etc) as the number of seconds since then, currently at the time I’m writing this, 1417577790. So basically we referenced a time of zero or nearly zero.

The Raspberry Pi doesn’t have a battery-backed system clock so every time it boots it starts with a system clock of 0. Usually the network time protocol daemon, ntpd, is able to get the time from somewhere. We have some stuff to recognize this and that may not have worked or this may not be the source of the problem, but anyway, we’ll look into it.

Interesting tidbit about time, if it says December 31st 1969 then there’s a timezone conversion in there (or a negative clock value). Vernor Vinge, a retired computer science professor and science fiction writer referenced this in his book A Deepness in the Sky…

Take the Traders’ method of timekeeping. The frame corrections were incredibly complex - and down at the very bottom of it was a little program that ran a counter. Second by second, the Qeng Ho counted from the instant that a human had first set foot on Old Earth’s moon. But if you looked at it still more closely … the starting instant was actually about fifteen million seconds later, the 0-second of one of Humankind’s first computer operating systems.


#5

I’m having the same issue on my KPWK PiAware feeder.


#6

Of three feeders, I am seeing it on the two that are not running. They were running earlier today and showed current when running. Yesterday or the day before the stats reflected the last day they had been running. Seems the last seen value is not being retained.


#7

What does “last seen” mean?

Does it mean the last time the rig reported a plane to FA?
Or does “last seen” mean there was a ping or handshake that took place with the rig?

In other words, if I located a rig on the South Pole with a crappy antenna (thus not seeing any planes) but with a good internet connection would ‘last seen’ be reported as a few minutes or days?


#8

I got the same error again today. When I reboot the pi it will broadcast data for a minute and then stop feeding data.


#9

Seeing the same thing on my SBS-3 feed
Last Seen: 1969-Dec-31 - 44 years ago


#10

.


#11

The “44 years ago” bug shows up when the device has been offline for more than an hour. It’s a server-side bug that will be fixed on Monday. Thanks!


#12

What does “last seen” mean?

Does it mean the last time the rig reported a plane to FA?
Or does “last seen” mean there was a ping or handshake that took place between FA and my rig?

In other words, if I located a rig on the South Pole with a crappy antenna (thus not seeing any planes) but with a good internet connection would ‘last seen’ be reported as a few minutes or days?


#13

“last seen” is when we last received a message from the ground station about an aircraft so, yeah, if you were on the South Pole it could be far in the past yet everything could be working fine.

Daniel and I have been discussing this and we’ve agreed that it would be good to also be able to say whether or not your ground station is connected to FlightAware, or when it was last connected, so we’re going to add that.

Thanks for the question; apologies for the delay in replying.