Medium Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Communication Breakdown; Situational Awareness; Time Pressure
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued Advisory / Alert; Flight Crew Requested ATC Assistance / Clarification
Airspace Structure; Human Factors; Weather
This was a horrible experience. We were trying to avoid thunderstorm heads and I advised ATC of heading and altitude that was needed to avoid a cell. ATC said no go heading 360 if you can't descend to 12;000 feet. We advised we were unable 12;000 feet due to a thunderstorm and needed a 010 heading. ATC argued with us. The Pilot in Command wanted one thing and ATC wanted another. Then ATC said if you're not going to descend then Traffic Alert head on course with 737 that ATC did not move either. Finally we stayed our course and maintained 16;000 feet and eventually turned on to our flight plan route. This was very dangerous for ATC to argue with us and we did hit moderate border line severe turbulence and scared our passengers trying to comply with ATC instructions. ATC should not have argued and the Pilot in Command should have talked to ATC directly rather than have me relay it. He should have transferred controls since I did not know what the Pilot in Command wanted.
Fractional First Officer reported ATC would not approve a deviation for weather resulted in an airborne conflict and severe turbulence encounter.