Date: 202202
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain; Check Pilot
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Training / Qualification; Communication Breakdown; Time Pressure
Second reporter function: First Officer; Pilot Flying
Anomaly: Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Hazardous Material Violation; Deviation / Discrepancy - Procedural Weight And Balance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew; Person Ground Personnel
When detected: Other Arrival gate
Result: General None Reported / Taken
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: While assigned to Aircraft X operating ZZZ - ZZZ1; I learned the aircraft had Accessible Dangerous Goods (ADG) on board that we had not been advised of as flight crew and was not reflected in the Aircraft Dangerous Goods Manifest. We were told of the error the evening after the flight landed in ZZZ1. We were later told that the [type] Dangerous Goods Container had ADG present; the Dangerous Goods was tied down and a DG ID Tag was in the container pouch; and the Unit Load Devise DG Manifest was also located in the container pouch rather than the DG Paper Envelope provided to the flight crew before departure from ZZZ. During our pre-departure procedures; we were provided two ULD DG Manifests for positions 4 and 5; and no ADG Manifest was provided. We later learned there was Class 3 and 8 Dangerous Goods in the [type] DG Container. [This discrepancy was caused by] Improperly manifested DG by DG personnel. [Reporter suggested the company] Implement cross-check process for DG personnel to follow. Have DG personnel include a check of accessible DG container even when DG manifest does not indicate it being present.


Second narrative: Flew  Aircraft X ZZZ-ZZZ1.  We received and checked the Aircraft DG Manifest from the DG Specialist.  The DG specialist informed us that we had no Accessible DG.  We confirmed this on the Aircraft DG Manifest.  The Aircraft DG Position summary showed two positions of DG - positions 4 & 5.  We confirmed that these positions contained the same inaccessible DG items.  The DG paperwork envelop contained only 2 ULD DG Manifests - position 4 and 5.  When we arrived at ZZZ1 ramp on the evening of Date; we were informed by the Ramp Agent that they had discovered a DG Discrepancy.   They discovered a [type] Container; XXX; which had class 3 and 8 DG.  Also; this contained was not hooked to a Halon hose.  Finally; the ULD DG Manifest was found in the container's pouch.  It was not in the DG Paperwork envelope.Improperly manifested DG [caused the undocumented DG to be transported].[Reporter suggested the company] implement a process by which the DG ULDs and Manifests are crosschecked by the appropriate personnel.


Synopsis: Air Carrier flight crew reported undocumented Dangerous Goods transported. Discrepancy occurred due to inaccurate DG manifest data and no onboard visual DG verification.