There are a couple of different reasons for gate assignments at ATL
1. Aircraft size:
Not all gates in ATL
can accommodate all aircraft. This has to do because of they way the concourses were designed and how far apart the gates are. Bigger aircraft need a wider parking spot. Delta (excluding Delta Connection)has gates on all concourses except for C. Widebodies are restricted to gates on T, E, and A. The gates on B and D can only handle narrowbody aircraft. The largest domestic aircraft DL
flies is the 767-400 which is restricted to certain gates on T and A. The gates on E, with some exceptions, can handle any size aircraft.
Flights into DCA
require special security arrangements which include having a police officer present during the boarding process. Delta has decided to operate these flights out of gates A-3 and A-5 in order to comply with the security directives and also the same agents work the flights on a regular basis and are familiar with the procedures.
Delta's flight schedule is revised a couple times a year. With every schedule change, operations personnel go through the entire schedule and develop a parking scheme that will fit. Since most flights operate on a daily schedule, the same flight is assigned the same gate almost every day. Of course IROPS and late arrivals/departures can cause havoc with this plan and must be changed accordingly. DL
have people known as "gatekeepers" that work in the ramp towers on top of the concourses who have the job of keeping track of the parking situation and advising all personnel of any changes.
4. International to Domestic or vice versa
Many times an aircraft will come in on a domestic flight and then continue as an international flight or vice versa. An example of this is DL147 SCL
which arrives at 0620 and then the aircraft continues on the AM
flight to LAX
. Likewise, most Latin America routes are flown on 737's or 757's which arrive from a domestic flight and depart to an international destination or arrive from international the fly a domestic leg. If you are booked on one of these flights then you will arrive or depart from E-concourse even if you are not flying internationally.
I hope this sheds some light on the matter. Cheers!
"I love mankind. It's people I can't stand." - Charles Shultz