M20J pilot reported communication breakdown with ATC while troubleshooting engine malfunction; resul...

Attributes
ACN	1679035
Time
Date	201908
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	M-20 J (201) / Allegro
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Route In Use	Visual Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Beechcraft King Air Undifferentiated or Other Model
Component
Aircraft Component	Engine
Person 1
Function	Single Pilot
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Commercial
Experience	Flight Crew Last 90 Days 300 Flight Crew Total 2600 Flight Crew Type 2000
Events
Anomaly	Aircraft Equipment Problem Critical Conflict Airborne Conflict Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Published Material / Policy Deviation - Procedural Clearance

Narrative:

Flying to ZZZ. Approximately 7nm northeast of ZZZ at 4000 MSL. I was being vectored for a visual approach runway 18. The engine started running extremely rough to the point I felt like it was going to quit. I told the tower controller that I had engine issues and needed to land immediately; nearest runway. I didn't hear a response; or it sounded like the controller was giving instructions to another plane. I turned directly towards runway 13 and started descending. I felt like I had enough altitude to make runway 13 if the engine died; so I started troubleshooting. I tried switching fuel tanks; no joy. I tried different positions on the key switch; no joy. I tried cycling the fuel tank selector; again; thinking that maybe I didn't quite select the opposite fuel tank detent. The engine started running a little better; at least to the point that the throttle was responding to power changes. The tower controller asked me if I needed any assistance; roll the fire trucks; I replied that the engine was running better and I knew I could safely land the plane. It was after I landed that the ZZZ tower supervisor called me and said there was a possible pilot deviation in that there was a hawker jet below me when I started descending and that there was a loss of minimum separation.

Original NASA ASRS Text

Title: M20J pilot reported communication breakdown with ATC while troubleshooting engine malfunction; resulted in an airborne conflict.

Narrative: Flying to ZZZ. Approximately 7nm NE of ZZZ at 4000 MSL. I was being vectored for a visual approach runway 18. The engine started running extremely rough to the point I felt like it was going to quit. I told the tower controller that I had engine issues and needed to land immediately; nearest runway. I didn't hear a response; or it sounded like the Controller was giving instructions to another plane. I turned directly towards Runway 13 and started descending. I felt like I had enough altitude to make Runway 13 if the engine died; so I started troubleshooting. I tried switching fuel tanks; no joy. I tried different positions on the key switch; no joy. I tried cycling the fuel tank selector; again; thinking that maybe I didn't quite select the opposite fuel tank detent. The engine started running a little better; at least to the point that the throttle was responding to power changes. The Tower Controller asked me if I needed any assistance; roll the fire trucks; I replied that the engine was running better and I knew I could safely land the plane. It was after I landed that the ZZZ Tower Supervisor called me and said there was a possible pilot deviation in that there was a Hawker jet below me when I started descending and that there was a loss of minimum separation.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.