In broad terms, the regulation makes a distinction between flying over “congested” areas and over areas that are not “congested.” In most aircraft, over “any congested area of a city, town, or settlement, or over any open air assembly of persons,” we are to fly 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet. Over “other than congested areas,” we are generally supposed to fly at least 500 feet over the surface, except over open water or “sparsely populated areas,” in which case we merely need to stay 500 feet away from persons, vessels, vehicles, and structures. We often get calls from pilots who did not think they were flying over a congested area and were thus safe to fly at 700 feet AGL. They may be rudely surprised by a letter of investigation from the FAA alleging a violation of § 91.119.
Minimum safe altitudes are an area where pilots should err on the side of caution. For one, it seems to be an enforcement focus that the FAA pursues more aggressively than other violations of Part 91 regulations. Indeed, § 91.119 is among the most cited regulations in FAA investigation reports. But moreover, the FAA’s view of whether an area is a “congested area” may differ from yours (it’s not the yellow outline on your sectional chart). And litigating that difference of opinions could cost you a fortune in legal expenses (although your legal expenses may be much less if you have Pilot Protection Services).
You may ultimately win at the NTSB and convince the judge that the area over which you flew was not congested. You may save your certificate in the process. Of course, you may lose too. But even if you win, the legal fees you may pay along the way will be substantial—they’re probably enough to install that new avionics panel you’ve been dreaming of. Instead, your lawyer might be getting that new panel.
The moral of the story is this. Some regulations are open to interpretation. When faced with an ambiguous regulation, there is usually a reading that is conservative and a reading that pushes the envelope. If you value your certificates and your finances, you should go with the conservative reading, especially when the ambiguity is found in a regulation that the FAA enforces aggressively, like § 91.119.
