This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
Couldn’t hold altitude and Cessna 172’s engine kept sputtering and wouldn’t run smooth at all, no matter what settings of carb heat, throttle, and mixture.
In the end full carb heat, full throttle, and full mixture were the settings that held power the best. The best power settings still couldn’t hold level flight, but did allow for a slow descent (200-300 fpm).
Flight scheduled to ZZZ and back for IFR time building for me and safety pilot.
Preflight had three things I should have noticed and said no to flying that day for two of them.
- Extensive black exhaust soot covering the bottom left hand side of the fuselage. (Red flag)
- Missing screws on the cowling
- The plane owner did not inform me that this plane had been in a priority handling event exactly one week prior or the findings from that flight.
Climb was 11 minutes to 6,500. Cruise was 20 minutes at 6,500. And descent was 13 minutes with engine never producing full power.
We both remarked how incredibly smooth the climb and cruise were. The air was perfect for flying. We were at 6,500 running at 2300-2400 rpm cruising into a 13 knot headwind for a ground speed of 75-77 kts.
While I had my foggles on, I continually scanned all flight instruments and engine instruments. I never noticed the carb temperature reaching lower than 0° Celsius.
When the engine hiccuped, we both felt and heard it immediately. We had just switched frequencies from ZZZ center to ZZZ2 approach. Was about to call up and ask for ILS XXL into ZZZ.
I initially thought mixture so pushed it rich and it smoothed up so I thought maybe he tapped the mix with his knee or something. Then 30 seconds later it coughed and almost started to die completely.
I looked at carb temp and it was right at 0° Celsius so I put on carb heat and it ran a bit rougher but seemed stronger.
It was at this time my safety pilot reminded me I had foggles on and said “you can get rid of those things.”
I told my safety pilot “I think we need to get to the ground, it’s not getting better, can you bring up Foreflight and find the nearest airport.”
He said ZZZ3 and gave me bearing. I pointed that way and called up Approach and requested priority handling, saying engine failure can’t hold altitude. At this point it was three to four minutes into it and I’d lost around 800 feet of altitude.
Approach said there’s a couple airports due west 20-25 miles I can head to since ZZZ3 was IFR. I looked that way and it was forest and ZZZ3 direction was fields and I reply “it looks clearer that way. I’ll try ZZZ3, but my glide says I can’t make it and these fields look better.”
I point it that way and the engine is still sputtering and my safety pilot says “what’s the best glide speed? There’s some good fields down here.” I say “I’ve got power (1200-2000 rpm fluctuations) I’m not ready to glide yet let’s try and make it closer.”
About eight miles out I can see ZZZ3 and it’s not IFR so I call up Approach and say I see it. Approach says do you want to switch frequencies and I say “nope, my glide circle still shows I won’t make it, I’d like to stay with you.”
So I slowly descend (not on purpose) like 200-300 fpm until I get four miles out and feel comfortable I can make the runway, so I pull up and slow up, put my flaps in at 10, and tell Approach I have the runway made and he goes “OK frequency change approved fly at your discretion.”
And I reply “frequency change approved, but I’m flying at this plane’s discretion. Thanks for all the help.”
Actually had to dump some altitude at the end and landed a bit long, but I’m very confident that I couldn’t have made it more than a couple miles past that airport. I think it was 15 miles away when the engine started having issues.
Upon landing, there was even more exhaust soot all over the bottom of the plane. This was more pronounced than during our preflight.
My safety pilot got a 99% on his PPL written test and the only thing he missed was what to squawk in this situation. I looked down a couple minutes into it and he squawked XXXX instead of XXXY. So he still hasn’t learned.
I have always wondered if I’d freeze or forget things in a situation like that and my training really kicked in. My safety pilot said he never felt nervous or afraid and I sounded like a pro. On the inside I felt pretty calm and in troubleshooting and flying mode. But when I landed I got out of the plane and was shaking.
They teach you power out emergencies and pitch for best glide, but when I had power I was resisting that urge. I wanted to lift up and keep wings level and keep a bit more airspeed while I still had a prop running. Not sure if that was right but slowing down to 80 seemed wrong with some power. I was right on the edge of wanting to pitch for best glide.
It’s still under some question as to what the cause of the problem was. My CFII believes it was carb icing, whereas others believe it was a faulty carb heater, faulty carb, or possibly a faulty induction system. It is still being investigated
If it was carb icing, then carb heat never fully recovered power during flight.
Primary Problem: Aircraft
ACN: 1953883
He doesn’t mention winds so I’m assuming they weren’t a factor. One would normally slow to best L/D for the best shot at making the nearest suitable airport.
One thing I’ve learned in my 45 years as a pilot is, it’s easy to second guess what the pilot should have done. They made quick decisions based on incomplete data. In an emergency no one reacts perfectly. Even Sully forgot to press the ditching button on his Airbus. The fact that these guys walked away shows they did well. The fact that the plane wasn’t wrecked is excellent.
I have a question… I am a student pilot ready to take his exam. Shouldn’t he have declared an emergency and landed at the airport that was ‘IFR’ and he would have had priority and not have had to travel 15 miles w/a bad engine?
No – he went to the nearest airport and barely made it with limited engine power (only two miles to spare). There was no option for an instrument approach with the engine problem.
I think he probably did “declare an emergency”.
In fact, for some reason, in places where a pilot would have referred to an emergency, or actually used the words “declared an emergency”, the ASRS reports replace it with “[requested priority handling]”. Brackets included.
I have no idea why.
Agree. My ‘no’ wasn’t clear. It was referring to any attempt to make an instrument approach which was not really an option, and the 15 miles was the closest runway. I think Douglas was thinking there was an instrument approach available closer than that.
No one ever says what the problem was
Interesting report but I don’t think it should be published till the fault is found and confirmed
The belly covered in black soot was a reason to ground the airplane until the problem was diagnosed and repaired. Pilot error
Yes, the aircraft should have been grounded. It looks like a serious flooding of the carb., either a stuck float, or debris holding the float needle open.
It good that he was able to get it on the ground ok.