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

Lndwarrior

Lndwarrior

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For the sake of argument:
1. You are cruising along at 7500 feet in your naturally aspirated single engine GA aircraft.
2. Nearest airport is 30 miles away.
3. Suddenly you experience a noticeable partial power loss.
4. Power loss is just enough to maintain altitude, but not enough to climb.
5. Oil pressure appears reasonable for the current power output.
6. You're over level terrain with good options for off airport landing.

A. How would you assess this risk?
B. What other factors would you consider besides the ones noted above.
C. How do you make the decision to continue to the nearest airport, or make a precautionary off airport landing?

There is a lot of discussions on complete engine failures, but not a lot on partial power loss in flight.

Posting because I really want to hear peoples opinions and thoughts on this subject, and hopefully come away with some insight to help in my own flying. Also hoping the thread doesn't get derailed with non-relevant bickering, but that may be asking too much. %^)
 
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.
 
Direct to closest airport. Continue to pick out good off field spots. Troubleshoot. I'm not landing off field just cuz it's running rough, it's still working at least partially...for now. At 30 miles the airport is roughly 15 min away. Probably hold descent off until I know the field is made. Can always slip, s-turns, circle, etc to lose altitude if need be.
 
A. How would you assess this risk?
B. What other factors would you consider besides the ones noted above.
C. How do you make the decision to continue to the nearest airport, or make a precautionary off airport landing?


A. Low risk of dying, high likelihood of landing safely at the airport 30 miles away. Don't panic.
B. Determine terrain elevation below. Your cruise altitude of 7500 feet is less relevant than your altitude AGL. (If you're flying over terrain near sea level you've got a lot of time and a lot of options.) Don't panic.
C. Wait until you NEED to land off field to make that decision. Head for the airport as plan A, be ready for plan B. Let ATC know about your situation so you don't have traffic conflicting on your course to the airport. . If you can maintain reasonable altitude with a reduction of power I would also consider doing that. Don't panic.

I've had at least five events similar to this, all eventually ending up at an airport. (Cracked cylinder, stuck valve, magneto timing gear, carb ice, fuel contamination.) The scariest of those was over the White Mountains of New Hampshire, when the engine quit, and I headed straight to an open field as the best option. As I went through fuel options, it came to life again, only to quit then restart, then quit again and restart. Once it smoothed out I headed to my destination airport and kept within gliding distance of good alternatives en route. It turns out that the problem was likely caused by a weird combination of a leaking fuel bladder dissolving the adhesive on tape inside the wing and then the dissolved glue entering the tank and blocking fuel flow until it further dissolved. We found little globs of adhesive in the fuel and replaced both bladders.)

Also, recognize that there will be a startle effect when the anomaly first appears. You'll be processing a lot of information all at once and need to be calm and deliberate in your decision making.
 
I think this is easy.

1. Basic power loss troubleshoot (switch tanks; fuel pump; carb heat things). it just might be something simple. If that doesn't solve it...
2. Turn to the nearest suitable airport.
3. Advise ATC if in contact and declare an emergency. Do it on 121.5 if necessary.

2&3 are reversible. We're talking a very short time For both. 3 before 2, especially if already in contact, has the advantage of getting assistance in finding that suitable airport and avoiding conflicts,
 
I had a partial power loss. Engine started sputtering too. We were low at about 2000. Found a suitable spot to land, trouble shoot. We headed back to the airport which was maybe 7 miles away.

I believe we climbed. I cant remember its been so long.

We weren't unable to climb though.
 
One thing to think about is the possibility of the windscreen being obscured by oil if the power decrease is the engine trying to kill itself. If you have the altitude to reach an airport, it might make sense to decrease power and perhaps kill the engine if the runway is comfortably made. I would guess that would be pretty apparent from severe vibration vs the engine just stumbling from a fuel issue or ice. It would also make sense to use an airport with a tower if you lose forward visibility.
Not a very likely scenario, but an example of why there is not a cookie cutter answer to your question. A flight school plane at DAB had to land that way using the ILS and the tower providing guidance on when to flare.
 
Partial power loss, I'd probably try to limp direct to nearest if it doesn't involve taking incremental risk from where I am now.
However, if that involves taking more risk by crossing hazardous terrain, going into any questionable weather conditions or getting into any densely populated areas where I'm less likely to have options to put it down in case things deteriorate, then I'm going be looking for a highway to land on.
 
1. Go through emergency checklist. (Fuel, carb heat mags, mixture, etc.)
2. Turn for nearest airport.
3. Contact ATC and declare if able
4. Identify potential off airport landing sites.

#1 may identify the problem and determine if making an airport is practical. Otherwise, the engine may fail at any time.

Been in this situation three times. First time was a cracked spinner on takeoff. Was close to airport and nursed it around on partial power while looking at the adjoining golf course fairway as an alternative. Second time was an unknown power interruption (possibly carb icing or ice in fuel pump), engine failed completely at 3000 AGL, field was made, then engine regained power about 30 seconds after emergency checklist completion. Safely returned to airport 7 miles away while gaining as much altitude as possible and keeping an eye on off airport alternatives. Third time was a mag failure on takeoff. Easily identified during emergency checklist. I COULD have flown 30 miles home, but that might have been stupid, since i didn't know if the mag failure caused any collateral engine damage. I just returned to the departure airport and got a ride home. Mag was replaced and I picked up the plane a couple of days later. I had no time to contact ATC during any of these evenfs, and was not in contact with ATC at the time of the incidents.

Hope is not a strategy. You must be prepared for power failure at any time if the cause is not identified. Simple issues, like a mag or fuel pump failure, carb icing, empty or clogged fuel tank, MAY give you more options.
 
Chrisgoesflying said:
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.
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machkhatib said:
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.
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These two cover it pretty well.

Prepare for the engine to quit.

Fly to nearest airport IF the terrain allows good options.
 
The previous owner of my plane had this happen. He tried to head to airport, but then the old Conti chucked a jug so he then setup for an e-landing in a nice looking field. Well he nearly tore the old girl up with a too fast approach, but stopped just shy of the barb wire. Old farmer came out to see what in tarnation was going on. Farmer was also a pilot and the two of them scrapped parts together to get airborne not long after. He regretted not immediately setting up for an off airport landing before things got worse (violent shaking). I have the full write up if interested. He had an oil leak on that jug, but dismissed it as normal or maybe pushrod tubes.
 
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Lndwarrior said:
For the sake of argument:
1. You are cruising along at 7500 feet in your naturally aspirated single engine GA aircraft.
2. Nearest airport is 30 miles away.
3. Suddenly you experience a noticeable partial power loss.
4. Power loss is just enough to maintain altitude, but not enough to climb.
5. Oil pressure appears reasonable for the current power output.
6. You're over level terrain with good options for off airport landing.

A. How would you assess this risk?
B. What other factors would you consider besides the ones noted above.
C. How do you make the decision to continue to the nearest airport, or make a precautionary off airport landing?

There is a lot of discussions on complete engine failures, but not a lot on partial power loss in flight.

Posting because I really want to hear peoples opinions and thoughts on this subject, and hopefully come away with some insight to help in my own flying. Also hoping the thread doesn't get derailed with non-relevant bickering, but that may be asking too much. %^)
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If the airport 30 miles away is across a mountain range or open water, I would abandon that destination and turn towards a different airport over friendier terrain, even if it is farther away.

If the engine is running smoothly, most likely it is carb ice, or perhaps the throttle cable became detached. Applying carb heat, switching fuel tanks, switching magnetos and adjusting throttle should reveal something. Assuming you mean 7500 ft AGL, that leaves a good 10 minutes in case of complete power loss. You have enough time to go through the written checklists.

Landing off-field should be the last resort, especially if I have adequate power to maintain altitude. I would not intentionally start a descent until I have the airport within gliding distance.
 
Why no consideration for glide ratio? At 7500 feet your typical Cessna has around 9 miles of gliding distance. I would consider that when heading to the airport 30 miles away. You just need a suitable off field landing spot within a 6 or 7 mile radius. You can still fly over unsuitable terrain on the way to the airport as long as you have some sort of off field spot available within gliding distance.
 
kmacht said:
Why no consideration for glide ratio? At 7500 feet your typical Cessna has around 9 miles of gliding distance. I would consider that when heading to the airport 30 miles away. You just need a suitable off field landing spot within a 6 or 7 mile radius. You can still fly over unsuitable terrain on the way to the airport as long as you have some sort of off field spot available within gliding distance.
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I'm curious why you think glide ration was not being considered in all the other answers?
 
midlifeflyer said:
I'm curious why you think glide ration was not being considered in all the other answers?
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Because it wasn’t mentioned anywhere. All the replies so far were either land immediately or go to the closest airport. The closest airport may not always be the best option when you also look to where you can glide to along the path to other airports. Things like open water shouldn’t matter if the water is only 10 miles wide and your glide ratio at altitude is more than half that distance. I may also consider further airports that are close to large towns that may have emergency services able to respond quicker if you do end up landing out unsuccessfully. That lone airport out in the middle of nowhere may be the closest but may not always be the best option if it’s only attribute is that it provides a piece of pavement that is close. You need to think through all options including how your altitude and glide ration plays into the decision.
 
kmacht said:
Things like open water shouldn’t matter if the water is only 10 miles wide and your glide ratio at altitude is more than half that distance.
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Don’t forget to figure how much more than half the distance it needs to be.
 
Hang 4 said:
A flight school plane at DAB had to land that way using the ILS and the tower providing guidance on when to flare.
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That would be a new one to hear over the radio:

"Cessna 12345, cleared ILS rwy 25. I'll call your flare."

* Yes, I'm sure it was more of a dialog to get to that point than that.
** Yes, I'm sure no one was laughing at the time.
*** Yes, congratulations on what I can only presume was a successful landing by the pilot w/ assistance from ATC.
 
kmacht said:
Because it wasn’t mentioned anywhere. All the replies so far were either land immediately or go to the closest airport. The closest airport may not always be the best option when you also look to where you can glide to along the path to other airports. Things like open water shouldn’t matter if the water is only 10 miles wide and your glide ratio at altitude is more than half that distance. I may also consider further airports that are close to large towns that may have emergency services able to respond quicker if you do end up landing out unsuccessfully. That lone airport out in the middle of nowhere may be the closest but may not always be the best option if its only attribute is that it provides a piece of pavement that is close. You need to think through all options including how your altitude and glide ration plays into the decision.
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I though it was implicit.

Nobody mention the requirement to land at the nearest suitable airport when an unairworthy condition presents itself either.
 
Lndwarrior said:
B. What other factors would you consider besides the ones noted above.
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The status and appropriate stated value of my Hull coverage? :)

That 30 miles is Hopium. That malfunctioning engine is now. It would be folly to fly the plane into a "no good landing areas" radius in that state. Assuming you're not already starting from such a place.

I'm human, so I would be staring at the path between me and that airport for a long time, but I'm gonna try to connect up a bunch of reasonable landing areas between me and there. If nothing immediately below me, I'm going to point at lower or flatter terrain as I am able to find. I will want to avoid my hand being forced over un-landable terrain.
 
Watch out for scenarios with airfields embedded in urban or suburban terrain. Saw a report last year where a pilot overflew numerous farmer's fields as he pushed into denser populated terrain trying to make his destination. He fell a mile short and landed in a Home Depot parking lot. Walked away but totaled his nearly new plane.
 
schmookeeg said:
It would be folly to fly the plane into a "no good landing areas" radius in that state.
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Ummm, we could talk about lots of different scenarios, but here's the OP's scenario:

"6. You're over level terrain with good options for off airport landing."

You're also at 7500 feet and able to maintain altitude, so you probably have a pretty wide radius of "good options" to land off airport, i.e (at least in this scenario) you've been dealt some excellent cards, and you still have a checklist that may reveal a simple, easily resolved problem such as carb ice, etc.
 
dbahn said:
Ummm, we could talk about lots of different scenarios, but here's the OP's scenario:

"6. You're over level terrain with good options for off airport landing."

You're also at 7500 feet and able to maintain altitude, so you probably have a pretty wide radius of "good options" to land off airport, i.e (at least in this scenario) you've been dealt some excellent cards, and you still have a checklist that may reveal a simple, easily resolved problem such as carb ice, etc.
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I was referencing the enticing nature of that airfield 30nm away :) I would not want to lose my "hole card" of level terrain to go chase that airport if there was un-landable terrain between me and said field.

If it was Kansas and one long continuous field between me and a tarmac runway... I'd probably try to drag the thing home and (hope to...) give it up if I could not hold altitude any longer.
 
Recently our club plane had an incident. According to the pilot, after reaching cruise altitude, the plane was unable to maintain altitude. Pilot assumed it was a partial power loss, when it fact this was a complete power loss. He mistook the normal readings on the manifold pressure and oil pressure to mean that the engine was still producing power, albeit at a lower rpm. He had plenty of altitude and was within gliding distance to an airport, so he landed uneventfully. Turns out, the problem was fuel interruption. Our plane has been experiencing unequal fuel draw from the tanks, so the pilot decided to set the fuel selector halfway between "Both" and "Right" in an attempt to equalize the flow. Surprisingly, this didn't kill the engine right away. Apparently it flew fine at cruise power for 15 minutes. Had the pilot landed off-field, this would have been a lot more serious. The lessons to be learned from this are: (1) be very cautious when trying anything new or nonstandard; (2) follow the emergency checklist (setting fuel selector to BOTH is the third item on the emergency checklist); (3) if the engine goes quiet without a loud bang or pop, chances are it is something you did, so don't rush to put it down in a corn field.
 
schmookeeg said:
I was referencing the enticing nature of that airfield 30nm away :) I would not want to lose my "hole card" of level terrain to go chase that airport if there was un-landable terrain between me and said field.

If it was Kansas and one long continuous field between me and a tarmac runway... I'd probably try to drag the thing home and (hope to...) give it up if I could not hold altitude any longer.
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Well, it's always a complex risk management challenge, because the options are constantly changing when you travel 30 miles, so the decision making is in a constant flux the whole time.

One thing to remember is that the field behind you that you've already flown over and inspected may be better than the unknown options ahead of you.
 
Unless, I'm on fire, I'll try to get to an airport. I can tell you in my situation, I started to get an engine vibration. I turned toward the nearest airport and hoped it would hold together. It finally (as we say in NASCAR) blowed up, and I looked for a good field to land in.
 
dbahn said:
and you still have a checklist that may reveal a simple, easily resolved problem such as carb ice, etc.
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The OP mentioned that the power loss was sudden and partial. Carb ice doesn't drop the power suddenly. It forms gradually, and gradually chokes off the carb. Oblivious pilots will not notice the airspeed or RPM loss and will just open the throttle some more. With a CS prop, the RPM won't drop until it's almost too late, but the airspeed and MP will fall.

There is far too much ignorance regarding carb ice. The training is horribly deficient, and the accident record shows it.
 
Ed Haywood said:
Watch out for scenarios with airfields embedded in urban or suburban terrain. Saw a report last year where a pilot overflew numerous farmer's fields as he pushed into denser populated terrain trying to make his destination. He fell a mile short and landed in a Home Depot parking lot. Walked away but totaled his nearly new plane.
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That's the thing about helicopters. Bad weather? Mechanical issues? No problem, land anywhere dry and flat, preferably with a road or civilization nearby but flat. Purely fixed wing drivers don't have that mindset. Gotta have an airport. Nothing else will do.
 
BTDT a couple of times. Both times have been over open fields with plenty of good landing options so heading toward an airport was low risk. My approach both times was to maintain altitude until I made it to the airport and do the troubleshooting I could to determine the problem and/or fix it.

In my experience, piston aircraft engines are tough and often give plenty of warning that they are unhappy. Even when the warning signs are ignored they'll often soldier on and make it to an airport where the problem can be fixed.
 
Unless there's bad terrain for an off-field landing in the direction of the airport I think you'd be nuts not to go for the airport in that situation. Maintain altitude until over it, make a circling descent above the field, and land.

In case of bad terrain... say it's in the middle of a crowded major metro area for example is there another option maybe 35-40 miles away surrounded by farm fields? An unplanned off-field landing carries it's own risks, there are all kinds of common obstacles that you probably won't see from the air until you're committed to landing. Ditches, fences, and power lines just to name a few. It still beats stalling and ending up a smoking hole in the ground but if you're holding altitude you really ought to try for the airport.
 
Piperonca said:
That's the thing about helicopters. Bad weather? Mechanical issues? No problem, land anywhere dry and flat, preferably with a road or civilization nearby but flat. Purely fixed wing drivers don't have that mindset. Gotta have an airport. Nothing else will do.
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What I would do depends on the aircraft I'm flying. In a helicopter I'd be more prone to make a precautionary landing somewhere and figure out what's wrong (I've never had to do that yet however). If I'm flying my airplane (a big tire Cub) I'd have no problem landing just about anywhere, but I'd probably still try to make it to an airport where there are tools and things. In an airplane that wouldn't do off airport stuff well, my first reaction is going to be heading toward an airport.
 
mondtster said:
BTDT a couple of times. Both times have been over open fields with plenty of good landing options so heading toward an airport was low risk. My approach both times was to maintain altitude until I made it to the airport and do the troubleshooting I could to determine the problem and/or fix it.

In my experience, piston aircraft engines are tough and often give plenty of warning that they are unhappy. Even when the warning signs are ignored they'll often soldier on and make it to an airport where the problem can be fixed.
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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.

Sure, I want to land somewhere convenient and check it out, but that old 'Conti' could decide to give up abruptly and shake the engine out of its mounts. That might render the aircraft unairworthy. Check the odds, place your bets.
 
Piperonca said:
All I can think of is folks trying to stretch a glide and impacting.
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That's a concern/issue, and it is one of the things I try and make sure any of my students understand and consider when I'm providing training. My suspicion is that best glide gets emphasized too much in training so that programs pilots to think about how far they can get, and they try and go the maximum distance rather than looking for an easily reachable landing area.

If we were to adjust the hypothetical scenario to being one where the engine power loss is significant enough that you can't maintain altitude I'd pick a field or a road somewhere and land off airport while being under control rather than try to stretch the glide in an attempt to make it to an airport. Perhaps that approach is due to primarily flying Cubs and having some helicopter experience though.
 
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