Date: 201707
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Regional Jet 700 ER/LR (CRJ700)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground ZZZ
Second aircraft: Rockwell Aero Commander Twin Turboprop Undifferentiated or Other Model
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Confusion; Situational Awareness
Second reporter function: Pilot Flying; Captain
Anomaly: ATC Issue All Types; Ground Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Aircraft; Procedure
Primary problem: Procedure

Narrative: We started an engine on the ramp prior to taxi. A Twin Commander was taxiing on the taxiway behind us and had not yet passed behind us. The taxiway was in very close proximity to our parking location on the ramp. The captain observed the Twin Commander over his left shoulder and the aircraft appeared to be stopped or moving very slowly. I did not observe the Twin Commander then or later. I called Ground for a taxi clearance. Ground cleared us to make a right turn and taxi to the runway parallel to this taxiway; which would have been in the direction of travel opposite that of the Twin Commander. We started the turn and after perhaps 30 degrees of turn Ground called again and told us to instead make a left turn and 'Sorry about that'. We made the left turn and started to taxi along the taxiway toward the departure runway. The pilot of the Twin Commander transmitted 'Thanks a lot; (unintelligible)'. I responded 'Thank you' or something similar. He then transmitted 'Thanks a lot; you spun me all the way around; that why I asked for idle power'. I did not respond. There was no response from Ground. The Twin Commander then asked Ground for their phone number and it was supplied. We stopped short of the runway to await our flow time. The captain then called Ground and asked him 'Did we pivot that Twin Commander?' and Ground responded 'That seems to be the consensus'. The flight was then completed uneventfully.We read back and executed the turn out instructions exactly as and when they were issued; including the reversal in the direction of turn. We were unable to see behind us and could not see the Twin Commander. We do not know if the Twin Commander was in the position expected by Ground or not. We did not hear any previous mention of idle thrust; though the radio transmissions from the Twin Commander to Ground were not very readable and we might have missed one. The thrust used was low; not much above ground idle - we were at moderate weight (approximately 67;000 LBS); the ramp was level and the turn was slow. It appears that the Ground controller might have been attempting to turn us left to point our engine exhaust away from directly across the taxiway for the Twin Commander to pass by; but in erroneously initially turning us to the right instead of left actually made the geometry of our engine exhaust with respect to the Twin Commander worse; causing the Twin Commander to encounter our jet blast.


Second narrative: This event may have been avoided if the controller would have made his plan clear to us or if we or the pilot in the other airplane would have asked some questions about that plan.


Synopsis: CRJ-700 flight crew reported being issued a taxi clearance from a gate which required a tight turn and full tiller. In the turn; jet blast was directed at a Twin Commander; which spun that aircraft around.