Military high level VFR?

[sf25]

Hi, this is an slf (with ppl) with a question:
was passenger on a flight yesterday. Flying at fl 400 westward over Hungary we suddenly saw some 5 planes, looking military (probably c17) coming exactly the opposite direction, slightly lateral offset but vertical separation was extremely low. Could that have been military vfr at fl 395? Weather was perfect vmc. Looked really scary to me ... ...

[itsnotthatbloodyhard]

Hi, this is an slf (with ppl) with a question:
was passenger on a flight yesterday. Flying at fl 400 westward over Hungary we suddenly saw some 5 planes, looking military (probably c17) coming exactly the opposite direction, slightly lateral offset but vertical separation was extremely low. Could that have been military vfr at fl 395? Weather was perfect vmc. Looked really scary to me ... ...

Almost certainly not. At high level, there’s a slight optical illusion in that something that looks the same level (until you get within a few miles) is actually 1000-2000’ lower. I’d imagine this is what you encountered.

[ATC Watcher]

There is normally no VFR above FL290 in Europe (*) and definitively no 500ft VFR crossing separation either , so most probably it was 1000ft which looks extremely close , definitively if it was a C17.

Note (*) exceptions for record flights in designated areas activated PPR. ( a couple are above the Alps to allow gliders records).

[Video Mixdown]

Hi, this is an slf (with ppl) with a question:
was passenger on a flight yesterday. Flying at fl 400 westward over Hungary we suddenly saw some 5 planes, looking military (probably c17) coming exactly the opposite direction, slightly lateral offset but vertical separation was extremely low. Could that have been military vfr at fl 395? Weather was perfect vmc. Looked really scary to me ... ...
NEODD & SWEVEN

[plans123]

Thought of checking FR24?

[mechpowi]

I don't know specifically UK and C-17, but generally it is possible to fly IFR as a formation, where ATC treats the formation as a single entity and the planes in formation are responsible to mainitain mutual separation (and a standard or a non-standard formation). I would guess that aircraft in question were flying IFR formation.

I can't post links, but search with "formation flying" should bring up the regulatory base for this.

[sf25]

NEODD & SWEVEN
.... that's what I thought, but as it looked much less than 1000ft vertical I thought of 500ft and vfr (which I found also weird)

[BEagle]

Although most nations impose limitations on the volume of airspace which may be occupied by formations, there is no universal definition of formation dimensions. ICAO provisions are that all aircraft within a formation shall operate so that the wing aircraft maintain a distance of not more than 1 nm laterally and longitudinally and a vertical displacement of not greater than 30m (100 ft) from the flight leader. These limits may only be exceeded at the discretion of ATC or when flying within the vertical airspace block assigned in an ALTRV.

[sf25]

Thought of checking FR24?
....good idea! Checked, and indeed there was qite some opposite traffic at fl390 (1000 below) at that time. .... My judgement seems to deteriorate. Thanks for Your comments folks ....