Skyhawk 172/Cutlass 172
Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 15; Flight Crew Total 420; Flight Crew Type 420
Human-Machine Interface; Other / Unknown; Physiological - Other
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Illness / Injury; Inflight Event / Encounter Other / Unknown
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport; General Physical Injury / Incapacitation
Aircraft
I departed ZZZ out to the North Practice area; outside the Class C airspace for routine training maneuvers in a Cessna 172.  The sky's were clear and full VMC. During the maneuvers I began to get airsick after I pulled open the cabin heat system.  After some time of using the cabin heat I closed the system and continued my training maneuvers thinking the airsickness would go away since it has never been a problem.  During my maneuvers I began to get cold again so I opened the cabin heat again and continued more maneuvers.  I continued to get airsick. During this period; I think about 30 minutes into the flight; I thought I smelled exhaust so I immediately opened the overhead cabin vents; opened the window and closed cabin heat.  I still felt alert so I did not consider myself impaired; just nauseated.  I picked up the ZZZ ATIS then contacted approach to return to ZZZ.  Approach instructed me to stay in the practice area due to traffic.  I continued circling in the area waiting for Approach to allow me to return.  I think by this time I had been flying for about an hour; not sure. I believe I was flying around 3000 feet. I continued to circle; but eventually started calling Approach to see if I could return because I wasn't feeling any better; but felt worse.  I am not sure if I was missing their radio calls.I eventually received permission to return on a heading of 150.  I turned to 150 and entered the Class C airspace.  Approximately 5 miles from the field I was informed I would be performing a box pattern to allow traffic to land ZZZ.  Approach or Tower (I can't remember) gave me a left turn to 100.  I remember immediately turning to the right thinking this would be more direct.  I realized I was confused and asked the controller to verify a left turn to 100 is really what they wanted me to do.  They confirmed the instructions so I made a left turn to 100 thinking this would be a complete 360 turn to 100 from my current heading of 150.  When I came to 100 I realized I was confused and this is when I realized I may be impaired due to CO poisoning.  ATC came back and asked be to make a left turn to 360 which I did and I believe I did acknowledge the instruction.  Some time after turning north I remember hearing ATC asking me if I copied their last transmission; which I realized I must have missed their call.  I responded by stating that I did not hear their transmission and that I was getting confused with their instructions and that I believe I was suffering from CO poisoning.  I believe I asked them to get me back to the airport as soon as they could.ATC gave me an immediate clearance to land runway 28.  I was able to turn the plane to 28 although I was very tired by this time.  During the final visual approach I noticed I was a little slow in responding to airspeed and power changes; but I was able to land the plane and taxi off the runway.  I met the fire trucks and sat on the taxi way for a while catching my breath.  I told ATC I thought I could taxi the plane to parking.  After parking the plane; EMTs met me at the plane.  I did not realize how impaired I was until the EMT's asked me some questions.  I remember the EMT asking me my name and I could not immediately tell him.  He then asked me how many quarters are in a dollar.  I could not remember and I had to take some time to figure out the answer.  I am writing this to inform of my experiencing and what I remember during the events and also to inform that I was able to land the aircraft without an accident.  After initial treatment by the airport EMT's I was transported to the hospital via ambulance.
C-172 Pilot reported executing an emergency landing due to Carbon Monoxide poisoning.