The Transportation Safety Board of Canada (TSB) has again called attention to the problem of passengers carrying luggage during emergency aircraft evacuations.

Passengers on a WestJet Boeing 737-800 slowed an evacuation earlier this year by bringing bags, says the TSB, marking the latest in a string of similar incidents that caught safety investigators' attention.

"Numerous passengers brought carry-on baggage with them, which slowed down the evacuation process," says the TSB's report into the 5 January fire and emergency evacuation of WestJet flight 2425 at Toronto Pearson International airport.

"Investigations into several other occurrences that involved emergency evacuations found that, as in this occurrence, passengers often attempt to retrieve their carry-on baggage during an emergency evacuation," says the report, released 11 July.

After landing at Toronto, the WestJet pilots temporarily stopped the 737 (registration C-FDMB) behind and perpendicular to a Sunwing Airlines 737-800 (registration C-FPRP).

At that time, tow operators employed by Swissport International began pushing back the Sunwing aircraft, which was empty other than a maintenance technician in the cockpit. The Sunwing 737's auxiliary power unit (APU) was running, the TSB says.

The Sunwing 737's tail struck the WestJet 737's right wing, and "a large ball of fire erupted", says the TSB.

The WestJet pilots ordered an evacuation.

Meanwhile, the tow operator pulled the Sunwing 737 away. The fire on WestJet 737 extinguished by itself and firefighters extinguished the fire on the Sunwing aircraft.

The TSB found that Swissport failed to follow its procedures by not using "wing walkers" to guide the Sunwing aircraft.

But the board also says the incident highlights the problem of passengers bringing carry-on luggage during evacuations.

Although WestJet's flight attendants told passengers during the evacuation not to take bags, some passengers took them anyway, the TSB says.

It notes that WestJet's pre-flight safety briefings do not address the luggage-during-evacuation issue, the TSB adds.

But neither do other airlines' briefings, says the TSB, which conducted a survey of safety briefings.

"None of the briefings on the observed flights provided this type of instruction to the passengers at any point before or during the flight," the TSB's report says.

The TSB addressed the same issue in 2007, when it recommended that Transport Canada require that safety briefings include instructions not to carry luggage during evacuations.

That recommendation responded to the August 2005 overrun of an Air France Airbus A340 at Toronto – an incident in which passengers also evacuated with carry-on bags.

Transport Canada subsequently addressed the issue in voluntary guidance, but has not taken regulatory action, TSB says.

The US National Transportation Safety Board (NTSB) has also addressed the same concern.

In response to a 2016 evacuation of an American Airlines 767-200 in Chicago, the NTSB in February recommended that the Federal Aviation Administration study the issue of luggage being carried during evacuations.

The FAA said it would respond to the recommendation by April 2019.