Date: 201702
Local time of day: 1201-1800
Location: ASE.Airport, CO
Flight conditions: IMC
Weather elements / visibility: Cloudy; 6
Light: Daylight
Aircraft: Gulfstream IV / G350 / G450
Operator: Air Taxi
Operating under: Part 91
Flight plan: IFR
Mission: Ferry / Re-Positioning
Flight phase: Final Approach
Airspace: Class E ASE
ATC / advisory: TRACON ASE
Second aircraft: Challenger 300
Reporter organization: Air Taxi
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor
Anomaly: Conflict NMAC
Detector: Automation Aircraft RA
When detected: In-flight
Result: Flight Crew Executed Go Around / Missed Approach; Flight Crew Took Evasive Action
Contributing factors: Procedure; Human Factors
Primary problem: Human Factors

Narrative: Weather at Aspen Airport: 5000 overcast; better than 6 miles visibility. In IMC on the ASE LOC DME-E approach; estimating between FIMSO (9.0 IASE) and DOYPE (7.1 IASE); estimating from 12;000 msl to 11;700 msl; airspeed 140 kts; gear down flaps 39 degrees (full);  we experienced a near mid-air collision with an opposite direction; climbing Challenger 300 (obtained by Aspen control) which was cleared for the LINDZ EIGHT DEPARTURE out of ASE.Both aircraft responded to a Resolution Advisory (RA) (we heard other aircraft report this information to Aspen control) and we immediately executed a missed approach and climbed according to the 'CLIMB; INCREASE VERTICAL SPEED' call made by our TCAS. During our escape maneuver; our 5 mile display on Display Unit 4 showed a RED '-02' almost superimposed on our position in the center of the screen.We elected to return to ZZZ and immediately were in contact with company including charter; dispatch and explained the situation. We called Aspen Control to learn further about how these events transpired. 1. Our arrival was mistimed for proper release of departing aircraft. We were faster on the approach than they expected which threw off their calculations for releasing the Challenger.2. The Challenger crew delayed their turn to the 273 degree heading 'At or above 9100'; which put us on a collision course. He was thus positioned much higher and further east of course than he should have been when turning left as he crossed our approach coarse and altitude simultaneously.3. ATC did not properly monitor the Challenger's departure and prompt the crew to initiate the left turn as called for in the SID. 4. Training for controllers at his facility would occur to address and correct this situation from happening again.5. He would file reports through the appropriate FAA system.I advised the Controller that from a pilot's perspective; having an aircraft cleared to depart directly opposite of another aircraft arrival IN IMC was a BAD IDEA! In mountainous terrain; below the peaks; super slow at full landing configuration it was much worse than a bad idea. If we were visual we could have had a fighting chance. In this case we were at the mercy of fate. Lessons learned.1. Acknowledgement that Aspen departures may/will be directed toward you on arrival. Situational awareness to this fact is paramount for the safety of ANY arrival be it visual OR instrument. There should be little assumption that you 'own' the airspace. Query of ATC as to their plan prior to these squeeze points and how they are managing the airspace would be advisable especially in IMC. 2. This incident is a strong argument that instrument approaches in IMC should be accomplished to a much higher minimum than published. In this case; if we would have been visual at the merge we could identify the oncoming aircraft. 13000 msl breakout prior to KICER (10.9) would have given that opportunity. That translated to about a 5000-6000 foot ceiling which we had. However; it should also be acknowledged that the weather over the field is often MUCH different on the approach than over the airport.3. LINDZ is both the departure fix AND the missed approach fix so altitude may be the only separation between aircraft. Plan accordingly.




Synopsis: Gulfstream IV Captain reported an NMAC during the Aspen LOC DME-E Approach with a Challenger 300 departing on the LINDZ 8 SID opposite direction.