Não encontrei uma definição definitiva de área congestionada .
Como mencionado aqui :
[...] neither the FAA nor the NTSB has ever provided [...] a precise definition of [...] a "congested area." Rather, a "congested area" is determined on a case-by-case basis. According to the Board, "the determination must take into consideration all circumstances, not only the size of an area and the number of homes or structures, but, for example, whether the buildings are occupied or people are otherwise present, such as on roads."
O mesmo é ecoado aqui :
[For the definition of congested area,] FAA and the NTSB have opted for taking a "case-by-case" approach in determining how to apply certain terms.
AOPA afirma que :
Congested areas. "Over any congested area of a city, town, or settlement, or over any open air assembly of persons, an altitude of 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft." The FAA does not define congested area in the FARs or in the Aeronautical Information Manual. Interpretations in low-flight enforcement cases are not consistent for purposes of drafting a precise definition. Such a determination is usually decided on a case-by-case basis, and in the cases that we've seen, congested has been interpreted rather broadly. For example, a highway with moderate traffic was found to be "congested," as was a seaside area where 200 to 300 persons were sitting on the beach or bathing in the water.