C172 instructor pilot reported detecting exhaust fumes while in the traffic pattern and elected to d...

Attributes
ACN	1433294
Time
Date	201703
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	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Route In Use	Direct
Component
Aircraft Component	Engine Exhaust System
Person 1
Function	Instructor
Qualification	Flight Crew Commercial Flight Crew Flight Instructor Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 136 Flight Crew Total 389
Events
Anomaly	Aircraft Equipment Problem Less Severe Flight Deck / Cabin / Aircraft Event Illness Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor

Narrative:

Exhaust gas leak on board while conducting a biannual flight review. Upon entering left midfield downwind; I noticed a smell of exhaust fumes in the cockpit and requested right turn out direct to ZZZ. Tower approved this turn out and we headed direct to ZZZ at 2500 feet. Upon reaching 2500 both pilot and I (instructor) began feeling symptoms of carbon monoxide poisoning. We slowed the aircraft down momentarily to open the windows to get additional fresh air into the cockpit. We then proceeded to close the windows so we could get our speed up to land back at ZZZ for a straight in approach. We requested all other traffic in the area to heed us so we could arrive with no delay and everyone flying at ZZZ made sure to stay clear and help us arrive as quickly as possible. I did not officially declare an emergency with ATC as it was more vital to communicate my intentions with the traffic currently flying at ZZZ which proved to be a huge help to us; however I should have declared an emergency with the other tower and landed there as soon as I smelled the exhaust rather than try to make it back to ZZZ.

Original NASA ASRS Text

Title: C172 instructor pilot reported detecting exhaust fumes while in the traffic pattern and elected to depart the pattern and return to home base.

Narrative: Exhaust gas leak on board while conducting a biannual flight review. Upon entering left midfield downwind; I noticed a smell of exhaust fumes in the cockpit and requested right turn out direct to ZZZ. Tower approved this turn out and we headed direct to ZZZ at 2500 feet. Upon reaching 2500 both pilot and I (instructor) began feeling symptoms of carbon monoxide poisoning. We slowed the aircraft down momentarily to open the windows to get additional fresh air into the cockpit. We then proceeded to close the windows so we could get our speed up to land back at ZZZ for a straight in approach. We requested all other traffic in the area to heed us so we could arrive with no delay and everyone flying at ZZZ made sure to stay clear and help us arrive as quickly as possible. I did not officially declare an emergency with ATC as it was more vital to communicate my intentions with the traffic currently flying at ZZZ which proved to be a huge help to us; however I should have declared an emergency with the other tower and landed there as soon as I smelled the exhaust rather than try to make it back to ZZZ.

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.