49 CFR § 175.31

Each person who discovers a discrepancy, as defined in paragraph (b) of this section, relative to the shipment of a hazardous material following its acceptance for transportation aboard an aircraft shall, as soon as practicable, notify the nearest FAA Regional Office by telephone or electronically. The nearest Regional Office may be located by calling the FAA Washington Operations Center 202-267-3333 (any hour). Electronic notifications may be submitted by following instructions on the FAA's website. The following information must be provided:

Name and telephone number of the person reporting the discrepancy.

Name of the aircraft operator.

Specific location of the shipment concerned.

Name of the shipper.

Nature of discrepancy.

Address of the shipper or person responsible for the discrepancy, if known, by the air carrier.

Discrepancies which must be reported under paragraph (a) of this section are those involving hazardous materials which are improperly described, certified, labeled, marked, or packaged, in a manner not ascertainable when accepted under the provisions of § 175.30(a) of this subchapter including packages or baggage which are found to contain hazardous materials subsequent to their being offered and accepted as other than hazardous materials.