The Air Carrier Access Act (ACAA) is a separate legislation that also was signed into law in July 1990. This law is specific to the airline industry and has some requirements for the airport itself.
All airlines are required to comply with the ACAA which has specific procedural requirements for the airline to provide safe and dignified air travel for people with disabilities. Many of the requirements of this law can be resolved easier with good planning in the design phase. Any airport related project should take more than ADA into consideration but should also review ACAA to ensure ease of compliance for the airline.
A copy of the Air Carrier Access Act can be found at: airconsumer.ost.dot.gov.