Comment by jkrejcha

Others in this subthread discussed the comparison of the complexity of different ways of achieving flight itself, but I think there is an interesting discussion in that... well... we do add senses we don't technically need to achieve stable flight (but are very useful for safe flight and have reduced the incidence of aviation incidents and accidents dramatically).

Whether it be altimeters based on radio[1] or air pressure[2], avoidance and surveillance systems that use radio waves to avoid collisions with other aircraft[3][4], airborne weather radars[5], sensors that measure angle of attack (AoA), GNSS location, attitude, etc, many aircraft (even unpowered gliders!) have some combination of special sensing systems that aren't strictly necessary to take off, fly to a destination, and land, even if some are required for what many would consider safe flight in some scenarios.

Many of these systems have redundancies built in in some form or another and many of these systems are even built into unmanned aerial systems (UASes) big and small.

[1]: https://en.wikipedia.org/wiki/Radar_altimeter

[2]: https://en.wikipedia.org/wiki/Pressure_altimeter

[3]: https://en.wikipedia.org/wiki/Traffic_collision_avoidance_sy...

[4]: https://en.wikipedia.org/wiki/Automatic_Dependent_Surveillan...

[5]: https://skybrary.aero/articles/weather-radar