Investigator 1: "The bridge was 20ft high, the combined height of the trailer and fuselage was 18.5 feet, that should have left a foot and a half clearance. Something doesn't add up"

*Exterior shipping depot*

Investigator 1: "So, can you show me how you load up these planes? Wait, are these the cross beams that you used under it?"

Investigator 2: "Would you look at that"

Narrator with 3d animation: "Normally when a plane is shipped like this, the crossbeams in use are 2 feet thick. However, all they had on hand that day were 3 foot thick beams for use with a heavier airframe."

*Back in the situation room*

Investigator 1: "So we know the plane was riding a full foot higher than was planned on that day."

Investigator 2: "But there was a foot and a half of clearance, it still shouldn't have been an issue."

Narrator: "The investigation was seemingly back to square one.:

*act break*

Narrator: "Investigators are trying to find a reason why a plane being transported by truck slammed into a bridge that should have had 18 inches of clearance. So far, they found that it was riding a foot higher due to changed crossbeams, but that still doesn't explain the missing six inches."

Investigator 1 looking at a newspaper article of the accident, notices a byline.

Investigator 1: "Hey, look at this. Record temperatures that day."

Investigator 2: "Oh wow, yeah. Do you think the tires could have been inflated more than normal?"

*Shipping depot*

Investigator 1: "What's the inflation pressure of the tires used for shipment?"

Worker: "85 psi, we check it before getting underway."

Investigator 2: "Can you show us?"

Worker: "Sure"

*proceeds to warehouse*

Investigator 1: "So this is where you check it?"

Worker: "Yeah"

Investigator 2: "Air conditioned"

Narrator: "We now know that the truck's tires were inflated to 85 PSI in a climate controlled hanger rather than outside in the heat of the day. This would cause the tires to inflate more as the trailer drove along"

*Back in the situation room*

Investigator 1: "Just how larger do you think the tires got on that day?"

Investigator 2 : "Let's find out."

Narrator: "Using a mock setup of the same tire and load, investigators first filled the tire to 85 psi and then heated the tire to account for the ambient air increase and the rolling resistance."

Investigator 1: "Wow, it grew!"

Investigator 2: "Yeah, but by only 4 inches, still 2 inches unaccounted for."

*act break*

Narrator: "We know that the plane was riding higher than normal due to crossbeams and higher than normal temperatures that day, but there still should have been two inches of clearance."

Investigator 2 looking at some records: "Hold the phone, that trailer just underwent an overhaul right before this trip."

Investigator 1: "Anything unusual?"

Investigator 2: "It had a tire replacement."

*back to warehouse*

Investigator 2: "Records show that the trailer had a tire replacement prior to going out, can we see those records."

Worker: "Sure, here they are."

Investigator 1 Reads records, then glances at a trailer parked near by soon to undergo maintenance: "Hold up, this is a different tire brand."

Worker: "Yeah, with the pandemic and supply chain issues, we had to switch suppliers."

Investigator 2: "Can we get specs on old and new tire?"

Worker: "Sure"

Investigator 1: "That's the smoking gun, the new tire is 2.5 inches larger in diameter than the old one."

Investigator 2 to worker: "Thanks for your time."

*situation room with two investigators now looking over paperwork*

Narrator: "A complete picture is now formed. Out of spec loading equipment combined with higher than normal temperatures and a policy to fill tires in a climate controlled hanger caused the load to ride higher than normal. What sealed the airliners fate though was the COVID pandemic and an inopportune maintenance that installed larger than normal tires on the trailer. The collision was set in motion in the early days of 2020, as groups of people started falling ill and the COVID-19 pandemic began."

Expert: "This just goes to show you how there's no such thing as a little supply chain disruption. Anything can have knock on effects."