Knowing what an airline can and cannot do for its passengers will provide a base for understanding what to expect from an airline. Be sure all baggage and travelers are in compliance with the law. The nature of aviation makes it an unpredictable form of travel. Prepare contingency plans before traveling.
Read Passenger's Rights
Go to the airline's website and find the section on customer service. Most airlines belong to the ATA, an airline trade organization that offers passengers flying on member airlines a "Customer First 12 Point Customer Service Commitment." Many airlines will follow this code or something similar.
Also, pamphlets placed at gate agent desks list airline policies and procedures for passenger complaints and issues.
Prepare to Follow Laws and Policies
The U.S. Department of Transportation (DOT) has a website dedicated to air consumers at: http://airconsumer.ost.dot.gov. Read the "Travel Tips" and the "Safety/Security Information" sections to avoid inadvertently violating the law.
Airlines like to be informed in advance if a passenger needs additional accommodations due to disability, etc. This allows time to gather necessary equipment, such as an aircraft aisle wheelchair, and additional personnel to assist.
Understand the Nature of Airline Travel
While all airlines make safety the highest priority, customer service may be compromised due to unforeseen circumstances, such as weather or equipment maintenance issues. While most flights operate on schedule, your anticipating and planning for delays or cancellations--and being flexible--will assist the airline in rebooking you or rerouting flights.
Airline customer service agents assist hundreds of passengers a day. These agents do not control operational decisions like canceling a flight or overbooking passengers, so they should not be blamed for any unanticipated changes. Most appreciate a smile and a grateful attitude and will often reciprocate with faster, friendly service.
Complain
If you encounter a problem, bring it--and a positive, non-confrontation attitude--to the gate agent. If the issue cannot be solved at that time, contact the airline through email or telephone. Ask the agent for this information. If all else fails, complain to the DOT's Aviation Consumer Protection Division at 202-366-2220 or http://airconsumer.ost.dot.gov/escomplaint/es.cfm. Be sure to include flight numbers, itinerary information and specifics about the issue.