WASHINGTON (AP) — U.S. crash investigators are urging the Federal Aviation Administration to require private planes to be equipped with carbon monoxide detectors, citing deadly crashes that were attributed to poisoning by the odorless gas.

The National Transportation Safety Board said Thursday that it identified 31 accidents since 1982 involving carbon monoxide poisoning, including 23 fatal crashes that killed 42 people and seriously injured four others.

The safety board said only one of the planes had a detector, and it lacked audible or visual alerts to the pilot. Carbon monoxide from engines can get inside the cabin through defects or corrosion in exhaust systems or other parts, the board said.

The FAA did not immediately comment on the recommendation.

The NTSB said it made a similar recommendation to the FAA in 2004. The FAA recommended that owners and operators of general-aviation planes install detectors, inspect exhaust systems and replace mufflers at regular intervals, but did not require those steps.