Liquid hydrogen. LH2. Imagine a pressurized cryogenic semi-trailer filled with LH2 traveling 75 MPH on I-25. An aggressive driver who's late for work cuts in front of the semi-tractor. The tanker swerves to avoid a collision but the sudden action causes the liquid to slosh violently, overturning the trailer. The tank ruptures. Sparks from the sliding wreckage ignite the hydrogen.
Remember the Hindenburg? Its 7 million-cubic-foot volume carried a full load of about 40,000 pounds of gaseous hydrogen. A 5000-cubic-foot cryogenic tank truck carries about the same amount in liquid form. Even though it is more than 400 degrees below zero, hydrogen still burns quite readily -- 4 on a scale of 0 to 4 in the NFPA 704 rating system. Gasoline is only a 3 on this scale.
Have you ever wondered what is in some of those tank trucks on the highway? Or what is hidden behind innocuous panels of a delivery van? Consider the following dangerous cargo:
A = Liquified petroleum gas
B = Thionyl chloride
C = Lithium metal batteries
D = Gasoline 
E = Sulfuric acid, 52%
F = Amyl nitrate
Y.YYY = (A + B + C)/1000
X.XXX = (D + E - F)/1000
N39 0Y.YYY W104 5X.XXX
You can check your answer for this puzzle on geochecker.com.