Under what condition may an aircraft operate under CFR 91 when carrying passengers or cargo?

The correct answer pertains to the regulations governing the operation of aircraft under CFR 91, specifically regarding the carrying of passengers or cargo. A Letter of Deviation Authority (LDA) allows operators to deviate from certain regulatory provisions under CFR Part 125, which governs passenger operations for larger aircraft. If an operator holds this authority, they can conduct flights that may not fully adhere to the standard requirements outlined in CFR 91, but still fulfill specific operational needs.

CFR Part 125 typically applies to larger aircraft and sets forth additional safety and operational standards. A Letter of Deviation Authority can be issued in instances where the operator can demonstrate that they can operate safely by following alternative methods. This flexibility ensures that operators can still carry passengers and cargo under established safety standards even when they do not meet every requirement of Part 91.

Flying under a special airworthiness certificate, on the other hand, typically does not cover the commercial operation of passenger or cargo transport in the same way as an LDA. A pilot-in-command declaration is more about the individual pilot's authority and does not provide necessary regulatory exemptions for the operation of the aircraft itself. Likewise, while passenger manifest approval is important for operational safety and tracking, it does not grant the necessary legal framework for