It's well known that SpaceX has a long term goal of getting people on Mars. Let's assume some time has elapsed since humanity's transition to Mars.
Due to lack of transport infrastructure and hostile terrain, humanity has settled down in separate zones set up in relatively habitable areas on the planet's surface. But now, it is observed that some people(scientists and such) will need to organize meetings for exchange of information. Due to vast distances between zones, planes are the only medium which can be used for transport.
What will the planes on Mars be like? Will hypersonic planes be the norm? Travelling by air on Mars needs you to be fast:
The tricky thing is that with so little atmosphere, to get any lift, you have to go fast. You need to approach Mach 1 just to get off the ground, and once you get moving, you have so much inertia that it’s hard to change course—if you turn, your plane rotates, but keeps moving in the original direction.