Living here in Atlanta and usually one of the first Uber Drivers in the staging area for the first flight arrivals I’m using different flight trackers to see when to expect pax and I always notice this departure of flight Mesa 698E / ASH698E (United Express) to KIAD (Dulles). You usually dont see a letter after the flight number. it’s an E170 and nothing special found with a search. It’s usually followed by MESA 6098 / ASH6098 an E175 a few minutes after. At first I thought it was an anomaly where a flight was duplicated but this is every morning
Honorable mention : Republic 4513 / RPA4513 leaves for Reagan National near the same time but from D Terminal and not from the coveted T Terminal like the others
ASH698E is the flight’s callsign, which is basically only used for communicating with Air Traffic Control. Many callsigns (especially in Europe, but nowadays a bit in the US too) include both numbers and letters to avoid confusion if flights with similar flight numbers (UA6098 and UA6088, for example) happen to be on the same ATC frequency.
The flight number is UA6098. Passengers will only deal with this, and will never hear or see the flight’s callsign. So, ASH698E and UA6098 are one and the same!
Flight trackers often get a bit buggy and think that a flight and its corresponding callsign are two separate flights. :)