Any luck if we weren't quite running test charges yet? Just wanted to use the subscription abilities.

This was absolutely unsafe and illegal. Regardless of whether they were conducting a flight for friends or not, they were operating an aircraft that requires two pilots at all times (per the FAA) with just one pilot (and a student pilot).

That's unsafe and illegal, even if the plane was otherwise empty. Even worse with passengers.

This has existed for quite a while. The SR-71 (introduced in 1966) had an astro-inertial navigation system that tracked stars to reduce error in a standard INS.

Using spectrum filters, was able to track stars day and night (and I imagine potentially in bad weather).

https://timeandnavigation.si.edu/multimedia-asset/nortronics...

Here's it as a required maneuver in 1995 :)

https://www.faa.gov/documentLibrary/media/Advisory_Circular/...

#1 is not accurate but for different reasons.

A forward slip is absolutely required for a PPL checkride and has been for decades (if you'd like a source, see page 45 of the definitive FAA ACS: https://www.faa.gov/training_testing/testing/acs/media/priva...).

However, transport category aircraft (among other issues) have swept wings, which are far less stable in a slip - so slips are neither taught nor recommended for jets.