Spaceflight

Some people never leave the ground, and others never touch the dirt. Both of them rely on each other, and on the engines whirring them through space.

— Gao Xue, Pilot

As it is the primary means of transport in the Interstellar Era, the majority of aircraft are capable of flying in space. Not all are built to the same standards or use the same methods to reach adequate spacefaring speeds, making each system's traffic unique.

Propulsion

There are three generally used methods of propulsion for spaceflight, used in different circumstances:

Chemical rockets, among the first used for spaceflight, are most common among ships that need the capacity to enter atmosphere. When they are a ship's primary thruster, that ship is usually limited to intrastellar travel, as most chemical rockets are not capable of reaching FTL speeds alone. Are sometimes used to enable ships with alternate propulsion methods to escape atmosphere.

Ion thrusters, a later development, are predominantly used for space-staying craft due to their efficiency in vacuum and difficulties in atmosphere. Capable of reaching lower FTL speeds, they are sometimes used by freighters going between systems, but more often remain in-system handling trips between satellites and orbitals such as OnRamps.

Warp thrusters, the latest form of propulsion, are capable of reaching exceptionally high speeds through minor distortions in space. Generally restricted from entering atmosphere, ships equipped with warp thrusters will typically operate solely as interstellar craft.

An additional method of propulsion, used to enable ships to enter an Interstellar Highway, are the OnRamps. These function similar to electromagnetic catapults, enabling ships to get close to the speeds required for safe operation on the highway, after which 'traditional' propulsion will be used for additional acceleration and course correction.

Power

Sources of power can be as varied as propulsion methods, where what type is used depends on location and cost efficiency.

Solar power is rarely the sole power source for a ship unless it operates exclusively in the inner reaches of a system, instead used as a backup power source for many intrastellar vessels.

Chemical engines are most common in lower-end vessels, due to the simplicity of manufacture and the perceived lack of risk to crew. The need to carry fuel is a significant factor due to weight and potential flammability, though technology has managed to synthesise more efficient fuels to produce more power per tank. Oxidising agents needed to achieve combustion can also contribute to weight for some ships, however the need to generate air for crew means this is rarely considered a factor.

Nuclear power is often used by interstellar craft due to the efficiency of power generation, with the significant costs and safety requirements offset by far higher cargo capacity and regular trips.

Navigation

In spaceflight, navigation is handled differently depending on the location and speed. Adjusting course based on visuals is only practical at low speeds, such as in atmosphere or on approach to orbitals. Traditional radar-based navigation remains popular, but can't be used in FTL, limiting it to intrastellar travel and to aid in docking procedures for interstellar craft.
Since visual and radar don't work above the speed of light, travel at these speeds will usually be based entirely on maths and pre-planned routing, with little capacity for manual adjustment by pilots. For ships travelling along the Interstellar Highways, the regularly-positioned pylons broadcast constant locational data to enable mathematical corrections. These will typically be handled by shipboard AI with pilot supervision, and in some areas such AI are a requirement for highway access due to the complexity of navigation, such as at highway junctions.

Speed Limits

Due to the technical challenges involved with safety at high speeds, these are extensively regulated, though the exact laws vary by region. The following are the general principles:
Ships travelling within a system are restricted to non-FTL speeds, enabling the use of radar and visual identification in transit. For the most part these ships' speeds can be measured in km/h, and will have lower limits in atmosphere or in orbit around stations and manned satellites.
Ships travelling between systems are subject to different rules depending on how they travel.
Those making use of an Interstellar Highway must be capable of reaching FTL 10, with maximum speeds varying across the network but usually being within the FTL 20-30 range.
Those not using the highway network are hypothetically able to travel at any speed, though the current practical limit is FTL 40 for civilian craft, and FTL 80 for military and government craft. These speeds are only permissible well outside the boundaries of a given system, and often with well defined routes between stars to avoid potential FTL collisions.

Even on the highway, thrusters are quiet and don't shake. Rockets rattle. Smell, too.

— Zayvia Eskarra, Pythian Gunner

Artificial

Subject to extensive regulation, shipboard AIs are intended solely to augment a crew's capacity to respond to situations, such as course adjustments at FTL speeds. They are never 'sentient' by any means, and function similar to simple autopilots. Ships are forbidden from solely operating under AI navigation, requiring supervision and maintenance by the crew.
Any accident attributable to an AI malfunction is automatically considered the fault of the ship's owners and manufacturers, as well as the pilot and managers on duty.