When it comes to private jets, it’s all about the need for speed. New York to L.A. in under four hours, multiple business meetings in different cities on the same day, home in time to tuck in the kids.

As time pressures increase, forcing most of us to go faster—and with private flyers, farther—jet makers are pushing the boundaries to develop aircraft that approach supersonic speeds, starting at Mach 1, or 767 mph, and faster.

That already happened with one new aircraft whose advertised speed is sub-sonic. In initial flight tests, Bombardier’s $78 million Global 8000 flagship hit Mach 1.015 (or 778.7 mph). Some analysts expect France’s Dassault Falcon 10X, scheduled to go into service in 2025, to exceed its predicted Mach 0.925 top speed.

In the wings, so to speak, are Concorde-inspired private jets from start-ups like Boom and Spike, designed for supersonic-plus speeds as high as Mach 1.7, or 1,300mph. That’s Atlanta to Madrid in four and a half hours, compared to eight when flying commercial.

Here are nine of the fastest private jets, most flying now and a few that may—or may not—eventually populate the skies.