A plane averted disaster after a fire was spotted in its hold just moments before it was due to take off.

The passenger jet was about to set off from an airport in Utah to Montana when ground crew spotted smoke coming from a bag and reacted quickly.

It turned out to be caused by an overheating lithium-ion battery, but can be seen as a narrow escape.

John Cox, a veteran pilot and  airline safety consultant with special expertise on lithium-ion batteries in aviation, said: “This could have been serious. Any time a lithium battery overheats the potential for fire and it spreading is very real. If the fire burned through the cargo hold lining it could have threatened the airplane." 

The fire had started in a toiletry bag.

The airline said: "We are proud of the quick work of our ground crew who recognised and helped extinguish a bag containing a lithium-ion battery that began overheating inside the cargo hold during the loading process.

"The situation underscores the importance of removing lithium-ion batteries from checked or gate-checked luggage.”

Fires involving Li-ion batteries have become frighteningly routine in the aviation world. In 2017, the Federal Aviation Administration in the USA reported 46 incidents on planes or in airports, roughly one every eight days.

By comparison, there were 31 such incidents in 2016, only 16 incidents in 2015, nine in 2014 and eight in 2013.

Mr Cox said: “It’s one of the few rising risks in aviation.”

Cargo holds are equipped with fire suppression systems that use Halon, a gas that suppresses flames by starving them of oxygen. But Li-ion battery fires are driven by internal chemical reactions that give off tremendous heat and Halon does little to reduce the temperature. The battery will tend to continually reignite and can even cause nearby devices to catch fire.

Federal Aviation Administration guidelines regarding the transport of spare batteries on flights state that spare Li-ion batteries should not be stored loose in checked luggage but instead packed in a carry-on bag. The electrical terminals should be taped or otherwise protected to keep the battery from coming into contact with any stray metal devices, which could cause a short circuit.

Though the FAA doesn’t require it, Mr Cox recommends carrying all devices containing lithium-ion batteries in your carry on luggage.

* AvSax fire containment bags are now on board several major airlines worldwide.

If an electronic device starts to seriously overheat or emit smoke the cabin crew will pour at least two litres of water into an AvSax and then drop the burning device into the bag, adding additional water as required.

The water activates the polymer gel inside the bag causing it to expand around the device. Should the device keep on venting then the AvSax is tough enough to absorb the force. 

The AvSax cools the batteries in the device, reducing the likelihood of the battery catching fire but if it does go into what is known as thermal runaway when all the battery cells catch fire at incredibly hot temperatures it is all contained within the bag.