Children under 2 should be required to have their own seats on airplanes and not fly on their parents’ laps, the National Transportation Safety Board says.

The safety agency, citing accidents that injured or killed young children,  sent a letter Wednesday urging the Federal Aviation Administration to impose a seating requirement on all flights for everyone on board.

The FAA has rejected the recommendation repeatedly, and the two agencies have debated the issue since the early 1990s. The FAA has maintained that the price of an extra ticket would give parents incentive to drive rather than fly, increasing highway fatalities.

The NTSB counters that the available evidence doesn’t support the idea that highway fatalities would rise. In its new letter, the NTSB argued that children under two should have the same level of protection on airplaces as other passengers.