In the Stark of 2219, the Scramjet is one of the preferred means of travel after the Collapse. It is much more primitive technology than the Hovercrafts and space ships of TLJ.

Charlie says that many of the customers of the Fringe "scram in, party, leave the next morning." When Emma comes to speak with Zoë she arrives from Europolis by Scramjet, and it is also Zoë's means of travel to Saint Petersburg.

In the real world, Scramjet is short for "Supersonic Combustion Ramjet" (a ramjet is a type of jet engine). It is presumed that such jets could reach a speed between Mach 12 and 24 (Mach 1 is the speed of sound).