Standards & Rulemaking

NTSB Safety Recommendations

About NTSB Safety Recommendations

PHMSA is required by law to respond to safety recommendations issued by the National Transportation Safety Board (NTSB), an independent federal agency charged by Congress with investigating significant incidents that involve hazardous materials.  Recommendations usually address a specific issue uncovered during an investigation or study and specify how to correct the situation.

NTSB Classifications

The NTSB has five classifications for open recommendations. Also, the NTSB closes recommendations when it has been determined that sufficient actions have been achieved. The NTSB organizes its closed recommendations into 11 classifications.

Open Recommendations Closed Recommendations
OAA - Open Acceptable Response CEX - Closed Exceeds Recommended Action
OAAR - Open Acceptable Alternate Response CAA - Closed Acceptable Action
OUA - Open Unacceptable Response CAAA - Closed Acceptable Alternative Action
ORR - Open Response Received CUA - Closed Unacceptable Action
OAR - Open Await Response CUAN - Closed Unacceptable Action/No Response Received
  CR - Closed Reconsidered
  CNLA - Closed No Longer Applicable
  CS - Closed Superseded
  CAAS, CAAAS, CUAS - Closed Acceptable/Acceptable Alternate
/Unacceptable Action Superseded

Status chart - by mode

Total Open Recommendations 21
Aviation 4
Highway 9
Intermodal 0
Rail 8

Status chart - by classification

Total Open Recommendations 21
Open Acceptable Response 17
Open Acceptable Alternate Response 3
Open Unacceptable Response 1
Open Await Response 0