ATSOCAS
I would be very grateful for ATC thoughts on this scenario:
IFR BizJet flight from Europe to busy Destination in the UK located in uncontrolled airspace with close proximity to busy RAF airfield.
We were instructed by London that our destination would accept us in the descent to 5000 feet and to fly direct xxxx (airfield) and contact xxxx approach. Upon making contact and continuing our descent as cleared the approach controller advised us that we had a traffic service and that we were to be vectored for final. We were instructed to turn on to a heading and our 5000 foot clearance was confirmed. We were in IMC and MSA was 2300 feet. On the assigned heading we were notified about target traffic in our 12 O'clock at 5000. Our TCAS display confirmed this and it looked from the display to be just inside of 5 miles directly ahead. This target traffic was currently at our cleared level and appeared to be directly on our track. I asked ATC if I could turn left or right to avoid this traffic. The reply from ATC was that we had a Traffic service and that the cleared altitude was 5000 feet. The controller had also explained that the traffic was military traffic manoeuvring up and down rapidly. The heading that we had been given was to avoid RAF base which was also busy.
I am aware that a Traffic Service leaves me in charge of my own collision/terrain avoidance but in this case I have a dilemma. My usual daily flying (all commercial IFR jet) requires that I obey ATC instructions and clearances. We were after all receiving vectors for a final approach and the controller reminded us about our cleared altitude. We were also on an IFR flight in thick IMC (cloud from approx 2000 up to 10000 feet). I am also aware not to use my TCAS display as a means of creating my own vectors to fly due to inaccuracies etc unless of course in the event of a RA. ICAO Doc 8168: PANS-OPS, Chapter 3, Section 3.2 details this and ACAS II bulletin No 6 'incorrect use of TCAS display' provides a good example.
In this situation I am not looking at a Topo chart since on my IFR flight I am not required to, nor am I visually familiar with the proximity of the RAF base to my destination. I could have requested a Procedural service but the vectors given were to aid my avoidance of the RAF base and it's associated traffic. A Deconfliction service was not offered. With simple Jepp plates in front of me and ATC instructions that sounded like instructions but were in fact guidance, both my colleague and I felt uneasy.
How are flight crew able to maintain their own traffic separation whilst operating in IMC? Do ATC expect flight crew to simply use assigned vectors and cleared altitudes as guidance in uncontrolled airspace? If flight crew start their own navigation over and above assigned headings and altitudes for traffic avoidance how do they avoid other airspace without a Topo chart? (Even with a Topo chart this is tricky due to work load and situational awareness coming from an IFR flight in IMC). From my perspective this situation feels like hit or miss and is quite unnerving. Any ATC perspective advice based on regulations rather than 'airmanship' is gratefully received for future visits to this and similar airfields.
Thanks in advance, sorry if it sounds a bit wooly.