Which of the following fuels is approved for US operations?

Jet A is approved for US operations primarily because it has specific properties conducive to the operation of modern turbine engines, which are widely used in commercial aviation, including the CRJ 900. Jet A has a higher flash point compared to Jet B and JP-4, making it safer to handle and store. It is also used in conjunction with standard operating procedures across many airlines in the U.S., ensuring compatibility with the fueling infrastructure.

Jet B, while usable, is not commonly employed due to its lower flash point and more volatile nature, which increases the risk of ignition and makes it less favorable for safety compliance in the U.S. aviation environment. JP-4 has been largely phased out from use in commercial aircraft due to similar concerns over safety due to its flash point and volatility, and it is not approved for use in the U.S. commercial aviation sector.

Thus, the confirmation that Jet A is the approved fuel reinforces its suitability for operations in the U.S. under current regulations and standards. This understanding is crucial for ensuring safe operational practices in aviation.