Letters after airline callsigns

[CRJDriver]

At Comair we have (had?) a lot of through-flights with the same flight number, example...

6654 OMA - CVG - PHL

So, the OMA - CVG flight callsign would be COM 654 and CVG - PHL would be 1654.

Dropping the first digit on the flight number is standard, if the flight continues on to another destination with the same flight number, they would replace the first digit with a "1".

 

[ZWflyer]

Air Wisconsin comes into ORF more often than not with an A appended to their callsign.

AWI581A
AWI597A
AWI603A
AWI71A
AWI85A
AWI881A
AWI91A

Being that this happens on a daily basis, I don't think it's because of delays.

They are all through flights. The company has finally realized that 90% of those flights are operated by the same aircraft and crew, therefore our "alpha" flights have been reduced dramatically. I used to fly at least one a day, but I haven't had one in over a month now.