How would you assess and respond to partial power loss in cruise flight?

Calling @wanttaja: What percentage of power loss fatalities are within 1 mile of airport? Within 5 miles? Or is this even a good problem statement? All I can think of is folks trying to stretch a glide and impacting. Recent sad events come to mind. Not advocating landing in farmer's field or sports arena, or even a road. All have risks. All of aviation has risks. It's just how much and where, and a multivariate equation at that.
I looked in the data dictionary for the NTSB accident database, and was surprised to find: "Distance from Center of Involved Airport".

I ran that against my Cessna 172 accident database, looking solely at the cases where a loss of engine power (due to either mechanical or pilot issues) occurred.

A couple of factors to be aware of: First, the data is from the CENTER of the airport...not the end of the runway the plane took off from.

And, second, the data provided is very coarse: A quarter mile resolution below one mile, then mostly integer-mile resolution beyond that. I would not anticipate the NTSB investigator is calculating this distance very closely.

Anyway, out of 2572 total accidents, of which 391 featured a loss of engine power, 179 included an entry for "Distance from Center of Involved Airport".

1697075054114.png
The 179 cases had an average of 7.4 miles, a median of 1 mile, and a maximum of 597 sm. If you get rid of this outlyer, the average drops to 4 sm.

I've done some extensive studies of loss-of-power accidents among the homebuilts. This might be a useful graphic:
1697075374465.png
Obviously, about 50% of the stalls after engine failures for homebuilts are occurring in the airport environment.

As far as landing in farmer's fields, don't know if you saw this graphic I posted to the McSpadden accident discussion. This is, again, data from homebuilt accidents:
1697075230242.png
The survival rate, even for objects such as buildings, is not that bad. What kills folks is losing control of the airplane while trying to force-land.

Ron Wanttaja
 
Reminded of the famous Bob Hoover engine failure. One of Bob’s favorite pieces of advice for new pilots was this: When faced with a forced landing, fly the airplane as far through the crash as possible.

https://check-six.com/Crash_Sites/N2300H-Hoover-1978.htm

On the afternoon of Saturday, May 25, 1978, Hoover had just completed performances in his P-51 and the Shrike Commander before an audience of 6,000. Having an appointment back at his home airport of Palomar, Hoover coordinated fueling his Rockwell 500S “Shrike Commander,” registered as N2300H, so he could leave right after the show was completed. When the young man asked how much fuel Hoover needed, he said he wanted precisely sixty gallons, adding ‘“That’s 100 octane.”

After Hoover’s performance, the pilot went to the airport manager’s office, where he received a phone call from the same young man, confirming that 100 LL (low lead) was all right for the airplane. Hoover confirmed that was correct, which the manager relayed over the phone.

Hoover had a practice of being present whenever the airplane was being serviced but was held up when coming out of the airport manager’s office. By the time he got to the Shrike, the fuel truck was pulling away. Hoover asked if the fueling was done, to which the line service boy replied, “Yes, sir. It was sixty gallons precisely.”

Hoover loaded his two passengers aboard and started the two 290 horsepower Lycoming IO-540 air-cooled flat-six piston engines. Taxiing out, scores of aircraft were ahead of him, awaiting clearance to depart from the field. But as soon as he called in, the tower said, “Mr. Hoover, we want you to taxi to the head of the line.”

Initially, Hoover was hesitant, not liking to leapfrog ahead of other pilots. However, since he was short for time, he accepted the tower’s offer, taxied on to the runway, ran up the engines, and made a smooth takeoff, heading north.

As Hoover recalled, “Everything was normal and checked out perfectly. All of a sudden, at about three hundred feet, I realized I didn’t have any power in the Shrike. I started losing airspeed.”

Instantly, he released the back pressure on the Shrike control yoke, but “couldn’t understand what was happening,” he recounted in his autobiography. “Everything checked out. The manifold pressure was right where it was supposed to be. The RPMs were at the right setting. The fuel pressure and oil pressure were in good shape. Even though the gauges indicated that nothing was wrong, I knew something was. I started looking for a place to land. That would not be easy.”

But Brown Field is atop a mesa, surrounded by deep ravines, and returning to the airport was out of the question. Hoover’s two passengers tried to remain calm, but were frightened, thinking that whatever that was going to happen would end poorly. “Mr. Hoover,” they asked more than once, “are we going to make it?”

Hoover assured them they would, relying on his decades of experience in anticipating trouble. He promptly pushed the control yoke forward to accelerate and maintain the plane’s best glide speed until it reached the very end of the ravine.

As Hoover bled off the plane’s airspeed, he lowered the landing gear and wing flaps to minimize the forward speed and inertia on impact. Down in a V-shaped ravine, it measured a thousand feet wide at the top, narrowing down to nothing at the bottom. Hoover flew down to the bottom to maintain the best glide speed, and pulled the plane up, placing it into the side of the ravine. The plane didn’t travel very far at all before hitting a rock pile that caved in the nose and ripped the instrument panel from its mounts and onto Hoover’s shins.


Neither the passengers nor Hoover were hurt. At the trio sat and awaited rescue, Hoover pondered what had caused the lack of power. He quickly deduced that there was only one possibility: the plane had been serviced with jet fuel instead of gasoline.

To confirm his suspicions, Hoover went around to the side of the airplane and opened the drain valve. Leaning down, he took a whiff of the fuel and was greeted with the distinct aroma of jet fuel. The plane had been able to take off with the remaining aviation fuel in the engines and fuel lines, but as soon as the jet fuel reached the engines, they cut out!

Hoover quickly recalled the young man he had asked to service the airplane and realized that he must have known by then what had happened as Hoover had informed the tower of the emergency.

Within minutes, rescue helicopters hovered over the wreckage, and the threesome climbed up the ravine to be transported back to Brown Field.
 
I looked in the data dictionary for the NTSB accident database, and was surprised to find: "Distance from Center of Involved Airport".

I ran that against my Cessna 172 accident database, looking solely at the cases where a loss of engine power (due to either mechanical or pilot issues) occurred.

A couple of factors to be aware of: First, the data is from the CENTER of the airport...not the end of the runway the plane took off from.

And, second, the data provided is very coarse: A quarter mile resolution below one mile, then mostly integer-mile resolution beyond that. I would not anticipate the NTSB investigator is calculating this distance very closely.

Anyway, out of 2572 total accidents, of which 391 featured a loss of engine power, 179 included an entry for "Distance from Center of Involved Airport".

View attachment 121345
The 179 cases had an average of 7.4 miles, a median of 1 mile, and a maximum of 597 sm. If you get rid of this outlyer, the average drops to 4 sm.

I've done some extensive studies of loss-of-power accidents among the homebuilts. This might be a useful graphic:
View attachment 121347
Obviously, about 50% of the stalls after engine failures for homebuilts are occurring in the airport environment.

As far as landing in farmer's fields, don't know if you saw this graphic I posted to the McSpadden accident discussion. This is, again, data from homebuilt accidents:
View attachment 121346
The survival rate, even for objects such as buildings, is not that bad. What kills folks is losing control of the airplane while trying to force-land.

Ron Wanttaja
Your first graphic tells me a lot of pilots aren't being taught to get the nose down aggressively after engine failure. Unless I'm missing something. Fixed wing not my thing but it's interesting.
 
Your first graphic tells me a lot of pilots aren't being taught to get the nose down aggressively after engine failure. Unless I'm missing something. Fixed wing not my thing but it's interesting.
The question is not just whether the pilots were TAUGHT that, but how long ago. I took my lessons 50 years ago, and had a ~10 year break where I didn't fly.

Sure, a BFR every two years. But it's not like the intensive training one receives during instruction.

Add, too, the currency of the pilots involved. Had a friend with a Bonanza. He flew 35 hours a year. One might argue that his skills weren't as sharp as one would hope (he did fine, finally stopped flying due to age). I fly about the same, but my airplane is much, MUCH simpler. FAA General Aviation survey says the average homebuilt pilot flies less than 50 hours a year.....

Finally, many of those stalls aren't due to bad training or rust, but due to fear. There's the instinctive desire to delay the crash, which probably leads to pulling the stick back too far. It takes real resolve to fly into the crash, and one is going to try delay or avoid it.

I'm all for better training, but I think more lives will be saved with safer aircraft. Starting with reliable engines and fool-proof fuel systems.

Ron Wanttaja
 
The thought that occurs to me in the scenario presented, is whether there is an area of no-return? That is, too far away from fields and not close enough to the airport? Remember, this is not an arcade game where the fields behind you are no longer accessible. You can usually turn back to a field that you passed earlier. (Yes, altitude, speed, etc allowing)

If there were an area where you cannot reach the airport or a field then that's going to be a judgement call. Do you think you're in a good enough situation to get across the bad area and to the airport, or do you take the safe option and take a field? This is going to depend on a lot of variables, too many to go over right now, w/o the inevitable follow up post of "You forgot <this> variable!"

If, on the other hand, there is no point where you cannot reasonably make a field landing, then by all means push on as if you need to put it down you'll have access to a field, but you might get lucky and get to the airport.
 
Agree with both of these. You're far better off rolling into the trees at the far end of a clearing going 30 knots, then you are stalling it from 200' at the near end of the field.
I've done some extensive studies of loss-of-power accidents among the homebuilts. This might be a useful graphic:
View attachment 121347

Ron Wanttaja

Reminded of the famous Bob Hoover engine failure. One of Bob’s favorite pieces of advice for new pilots was this: When faced with a forced landing, fly the airplane as far through the crash as possible.
 
I've had this happen once in over 20 years. Adding carb heat solved the problem. A little ice in the carburetor caused the loss of power and adding some heat solved the problem. If it hadn't then we probably would have declared an emergency and dealt with it that way.
 
Had it happen. Advise ATC and do NOT descend until you are OVER your new destination airport (or suitable landing spot). Go to the approach end of the assigned runway and begin a spiraling descent to a landing. Mine happened at night and I did a spiraling descent from 8,000 feet directly over the runway threshold at a Class D airport. ATC was extremely helpful.
 
And have a landing spot in mind at all times while you are doing your diversion. My engine failure presented itself as a rough running engine and I hit NRST and turned toward that airport. Before I got too much along toward that the thing handgrenated and I was spiralling down over the only empty field in the vicinity. Fortunately, I live on a grass runway so power off approaches to grass are pretty second nature. I just treated it like a normal landing. Would have been perfect if there hadn't been an (invisible to the air) electric fence (just a couple of wires and wood posts) across the thing (cow pasture).
 
Fuel exhaustion can initially present as partial failure. Small amounts of fuel are still sloshing around in the tanks, covering and uncovering the fuel line intakes. Depending on fuel system design, this can result in engine stopping, restarting, and surging several times. This can go on for a surprisingly long time, maybe 30 seconds to a full minute. Every time it restarts, you hope maybe the problem has resolved itself. That hope can prevent you from making a timely decision and move you away from your best option for an emergency landing.

Hope is a dangerous thing, because it is not fully rational. Better to commit early and decisively to a course of action with good odds of success than delay action because you hope the problem will go away. IMO a good rule of thumb for partial power loss is NEVER leave an area with suitable off-airport options and cross a less suitable area in hopes of making an airport. If you are near an acceptable emergency option, such as a private grass strip or a suitable open field, turn towards it and circle while you troubleshoot.
 
Fuel exhaustion can initially present as partial failure. Small amounts of fuel are still sloshing around in the tanks, covering and uncovering the fuel line intakes. Depending on fuel system design, this can result in engine stopping, restarting, and surging several times. This can go on for a surprisingly long time, maybe 30 seconds to a full minute. Every time it restarts, you hope maybe the problem has resolved itself. That hope can prevent you from making a timely decision and move you away from your best option for an emergency landing.

Hope is a dangerous thing, because it is not fully rational. Better to commit early and decisively to a course of action with good odds of success than delay action because you hope the problem will go away. IMO a good rule of thumb for partial power loss is NEVER leave an area with suitable off-airport options and cross a less suitable area in hopes of making an airport. If you are near an acceptable emergency option, such as a private grass strip or a suitable open field, turn towards it and circle while you troubleshoot.
Thanks for posting this. How much of this post is a reflection on your trip to Oshkosh and how much of it was in the front of your mind when you took off that day?
 
It’s an emergency. The engine may quit at any moment. Identify potential landing spots. Run through my checklists and communicate.

What is the terrain like between me and the nearest airport? If I’m over an area with prime fields to safely land and I have to cross mountains or other hazardous terrain to get to the nearest airport, I may opt to land now. Similar question with respect to weather and daylight. If it’s VFR / day now but IFR / night by the time I get to the nearest airport, I may opt to land now. These factors are all about reducing my risk.

Assuming the terrain is the same between the occurrence and the nearest airport, I would say risk is low to continue. I would first point the nose towards the closest airport and then try all the tricks like carb heat, fuel pump, changing tanks, etc.

I once had a partial power loss on takeoff. Happened too far into the climb for a landing on the remaining runway but not high enough to make a 180 safely. Since it was just a partial power loss, I still had a little bit of a climb (like 100 ft/m), I decided to just let tower know and do a normal pattern. Once I was on downwind (not yet at pattern altitude), I was also on base for the cross runway so I asked for it instead of doing the full pattern. In my opinion, there was no need for me to land straight ahead or make a radical turn back to the runway at low altitude without the full power of the engine. The terrain around the airport was pretty much the same all along so I figured if the engine completely goes, there will still be fields regardless but maybe I have a chance to make it back to a runway in the most routine way I know (by flying a pattern) and it worked out fine.

I know, different situation than the one you described but I guess similar enough to get an idea of the thought process I went through.

These.

I had a partial power loss on take off in a C-172. Likely a stuck valve (150HP running 100LL). I had a small rate of climb, so I turned to fly a pattern to land. On downwind, the problem cleared. So I circled over the field until I had enough altitude to glide to the next airport and then hopped home, always within gliding distance of 2 airport.
 
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