IFR training in a one-man airframe? That's very odd in the civilian world. One-man planes are rare enough, but a one-man plane with full instrumentation would be something special. And to then use it for training?
I suspect this crash is the result of a gap in FAA regulations. I would suggest that no pilot should be doing IFR training alone while around aircraft not flying IFR. But I can see why the rule doesn't exist: it is an extraordinarily rare situation that, probably, nobody thought needed covering.
This is one of the reasons that American's and Brits go to Goose Bay for low-level training. Canada has more empty sky than either of them combined.
And if the pilot is simulating instrument conditions, there is a rule: FAR 91.109 "No person may operate a civil aircraft in simulated instrument flight unless - The other control seat is occupied by a safety pilot who possesses at least a private pilot certificate with category and class ratings appropriate to the aircraft being flown".
If not simulating IMC, it's the pilot's responsibility to see and avoid per 91.113(b)
They do not fly simulated IMC ("under the hood") in F-16s. By the time the pilot gets anywhere near a F-16, they have already trained for IMC in multiple trainer aircraft.
FAR 91 doesn't apply to military aircraft, although military rules require they maintain a visual scan outside the aircraft.
The F-16 was on a training mission. It was also flying under IFR. That doesn't necessarily mean that the pilot was doing what we think of as "IFR training" (view limiting devices, etc).
It's perfectly normal for a training, proficiency, or currency flight to be operated under IFR, even single pilot.
I suspect this crash is the result of a gap in FAA regulations. I would suggest that no pilot should be doing IFR training alone while around aircraft not flying IFR. But I can see why the rule doesn't exist: it is an extraordinarily rare situation that, probably, nobody thought needed covering.
This is one of the reasons that American's and Brits go to Goose Bay for low-level training. Canada has more empty sky than either of them combined.