A backup pump engaged just minutes before the accident, as did an automated safety system that reduced the freighter engine's speed.

A backup pump was switched on, and it succeeded in loading the oxygen tank to capacity.

The backup pump was the one that failed to start last Friday, but the installation of new electric switches appeared to correct the problem.

If that is a concern, buy a backup pump that runs on 12-volt batteries.

If that is a concern, consider buying a backup battery-powered pump.

Since bilge pumps can fail, use of a backup pump is often advised.

Experts recommend a backup pump for every two you have on board, just to be on the safe side.

We've got a backup pump if the main isn't working.

"Better use the backup pumps."

"Those were the backup pumps," Zavala said.