AC Flight Numbers...?
 

This...is probably an ignorant and stupid question, but I am booked YVR-YYZ next year (en route to TLV ^ ), and I noticed the flight number is AC1166....my question: why the four digit number? Aren't YVR<->YYZ flights normally like 13x or 14x or something like that?

What do the four numbers mean, if anything at all?

I do know that all eastern & southern flights on AC are all even numbers and all western & north bound are all odd. Beyond that, generally lower numbers used on TransPac flights, while certain series, such as 1800's, generally used for quasi-ACV/AC flights and other for codeshares such as 9000 series.

Thanks...I did already know about the 1800 and 9000 series numbers, but other stuff was new.

It's strange cuz the return flight is AC151...normal YYZ-YVR flight (not that the other one isn't)...huh.

Under the pre-AC/CP system, which is still mostly intact (and I'm sure there may be an error here or there):
0000-0099: Asia Pacific and South America (inherited from CP)
0100-0199: Transcon
0200-0299: Western, but largely western triangle rapidair
0300-0399: Transborder
0400-0499: YYZ-YOW/YUL rapidair
0500-0599: (Can't remember, but I don't think this series is used)
0600-0699: Eastern
0700-0799: Transborder
0800-0899: Europe, Middle East, India
0900-0999: Caribbean
1000-1399: Domestic (largely transcon) and transborder overflow numbers (began appearing following AC/CP merger)
2000 series: Used as replacement flight numbers
5000 series: UA codeshares
6000-6099: AC Tango
7000 series: Regional
8000 series: Mostly regional
9000 series: Codeshares with other airlines

The 500's are largely Transborder as well. (ie:SEA, PHX and the LAS flights.)