Few people enjoy arriving too early for a flight and sitting at the airport for hours. Even worse is arriving too late and missing your flight. Airline rules, the size of the airport and the time of day are all factors to consider when deciding how early to arrive at the airport for your domestic flight.
Always arrive at the ticket counter by the airline's check-in deadline. Airlines differ slightly with their required check-in times for domestic flights. American Airlines and United Airlines both require that you check in 60 minutes before the flight if you are travelling without baggage and 90 minutes if you have luggage. Delta Air Lines requires a 45- to 60-minute check-in, depending on which airport you are flying from, for travellers with bags. Check with your airline to ensure that you meet the deadlines. If you show up late, the airline can deny you boarding on the flight and does not have to accommodate you on another flight, though often they do. Most carriers also have deadlines for the time you must arrive at the gate. Even if you check in on time, if you are late to the gate, the airline can give your seat away and make you take a later flight
The airlines' requirements are good general guidelines, but they do not take into account the waiting time at the ticket counter or the time it takes to clear security. A good rule of thumb is to be at the airport two hours early for any domestic flight. The airport you are flying from and the time of day you will be flying are also factors to consider when planning your arrival time. For busy airports like those in Los Angeles, Boston, New York and Atlanta, you should arrive three hours prior to you flight. If you are travelling during the busy hours of 6 a.m. to 10 a.m. or 4 p.m. to 7 p.m., you should allow extra time.
Most airlines will let you check in online and bypass the counter if you are flying without luggage. With online check-in, you can print your boarding pass at home or at an airline kiosk at the airport and go directly to the security checkpoint.You can still check in at home if you have luggage, but you will need to check your bags either kerbside or at the ticket counter. To reduce wait time in the security line, follow the Transportation Security Administration's rules for carry-on luggage and have your bags ready when you reach the screener.