Expectation Bias and avoiding gear up landings

[A64Pilot]

6 hours ago, ArtVandelay said:

That’s not what I’m saying…I know how to fly.

How do the gear up pilots get down to landing speed (for example 71 knots or less in my J) while descending without noticing their normal power settings aren’t working? (I assume it would be noticeable, I’ve never tried landing without the gear being down, I will have to try it, but not the actual landing part of course).

Once you get slow, the additional drag from gear has much less of an effect, my over the fence speed as I’m often landing on shorter field s is 65 to 70 kts, and I don’t think gear makes much difference when your that slow.

I make gear the first thing I do, it’s my opinion if you delay it to where your doing other things it could get lost in the mess so to speak.

I don’t bother with fuel to the fullest tank as I think it silly. Ones at 1/2 the other 3/4, you really think it matters? I’m too old to push fuel anymore, I just don’t do it,  less stress.

We have all or will all do stupid things, it’s called SLOG, or sudden loss of judgement. It’s the only explanation why for example someone always takes the same route to work for the last ten years and always stops at the stop sign, but for some reason today they run it. How else can you explain that? But it happens.

Best defense against SLOG is a second person backing you up, and if that’s not available, rigid adherence to a checklist 

[PT20J]

8 hours ago, Will.iam said:

Ironic i did the same thing for taking my plane down to annual as my right tank has leak on top underneath the step sheet that i wanted them to fix. I ran mine dry straight and level as i wanted to know how many mins i had left from the moment the low fuel light came on to when the engine quit. Never thought about if i could get anymore fuel / time out of the tank by slipping or raising the wing. Did you do these slips and other maneuvers before the engine started sputtering due to lack of fuel or when the low fuel light came on? 
if the former, how much longer did the engine run?

for the curious, i was running LOP and 7.1 fuel flow which got 32 mins and fuel totalizer showed 3.9 gallons from the moment the low fuel light came on to engine quitting. 
I’ll test the left wing after i get the plane back to see how many mins the low fuel light in left tank shows.

I was maneuvering after the low fuel light came on but before the engine quit trying to see if the maneuvers could unport the tank outlet at low fuel levels. If there was such an effect it was minimal because the engine ran fine up until the point where it just quit.

I did a quick swap of the drains. It didn’t seem like there was much in there, but I wish I had drained the tank and actually measured what remained. 

According to the POH, the low fuel light come on at 2.5 - 3 gallons useable fuel and the unusable fuel is 1.25 gal. 

Skip

[Will.iam]

38 minutes ago, PT20J said:

I was maneuvering after the low fuel light came on but before the engine quit trying to see if the maneuvers could unport the tank outlet at low fuel levels. If there was such an effect it was minimal because the engine ran fine up until the point where it just quit.

I did a quick swap of the drains. It didn’t seem like there was much in there, but I wish I had drained the tank and actually measured what remained. 

According to the POH, the low fuel light come on at 2.5 - 3 gallons useable fuel and the unusable fuel is 1.25 gal. 

Skip

If my low fuel light is calibrated at 2.5-3 gallons and not off it would confirm my suspension that my k factor is off on my fuel flow meter as for me to get poh speeds I’m at 1 gallon higher than published. Especially when the charts for below 65% power are to lean to peak TIT and that puts the fuel flow about 1 gallon higher. Would also explain the high cht on takeoff if Fuelflow showing 23-24. That really is 21-22. 

[PT20J]

50 minutes ago, Will.iam said:

If my low fuel light is calibrated at 2.5-3 gallons and not off it would confirm my suspension that my k factor is off on my fuel flow meter as for me to get poh speeds I’m at 1 gallon higher than published. Especially when the charts for below 65% power are to lean to peak TIT and that puts the fuel flow about 1 gallon higher. Would also explain the high cht on takeoff if Fuelflow showing 23-24. That really is 21-22. 

I wouldn't put too much faith in the fuel quantity at low fuel light activation unless you calibrate it. It's an analog system and it's unknown how accurately it was originally set at the factory.

I have spent a lot of time trying to get my Floscan fuel flow transducer calibrated. It's pretty close at a K-factor of 30.50 which is similar to what other's have reported. What I've found is that accuracy seems to vary depending on the actual fuel flow, so a bunch of short flights will not give quite the same total consumption as one long flight of the same duration.

The device is an interesting design: The fuel is forced to swirl as it flows through the device. A pinwheel made of a plastic with neutral buoyancy in gasoline rides the swirl and the vanes of the pinwheel interrupt a light path between a light source and a phototransistor. I can see this design perhaps being prone to errors during transient changes in fuel flow, so perhaps it is the power changes that create the errors. Without a flow bench, it's hard to tell. Flowscan does not specify accuracy other than steady state.

Skip

[Will.iam]

27 minutes ago, 1980Mooney said:

I think you have confused two different things.  This about measuring the static level of fuel in the tank.....not the fuel flow rate.

Understood. That is why I’m not basing my flow rate or totalizer being off of the low fuel lights but i am putting a lot of weight into my poh charts that say for a given MP RPM and lean to TIT my fuel flow and airspeed should be what is charted. And when i set the MP RPM and TIT my airspeed is correct in the charts for my weight but fuel flow is one gph higher than what the chart says it should be. When i set fuel flow in the charts, my airspeed is 20 kts slower and I’m LOP on the TIT. The fact that I’m getting 3.9 to fuel starvation is just another data point that is confirming my fuel flow is reading higher than what is actually flowing through the line. Once we get the k-factor adjusted so the fuel flow matches the POH charted fuelflow for the MP RPM and leaned to TIT i bet the fuel totalizer will also show more inline with 2.5-3 gallons when the light first comes on instead of the 3.9 it’s showing now. 

[Guest]

1 hour ago, PT20J said:

I wouldn't put too much faith in the fuel quantity at low fuel light activation unless you calibrate it. It's an analog system and it's unknown how accurately it was originally set at the factory.

I have spent a lot of time trying to get my Floscan fuel flow transducer calibrated. It's pretty close at a K-factor of 30.50 which is similar to what other's have reported. What I've found is that accuracy seems to vary depending on the actual fuel flow, so a bunch of short flights will not give quite the same total consumption as one long flight of the same duration.

The device is an interesting design: The fuel is forced to swirl as it flows through the device. A pinwheel made of a plastic with neutral buoyancy in gasoline rides the swirl and the vanes of the pinwheel interrupt a light path between a light source and a phototransistor. I can see this design perhaps being prone to errors during transient changes in fuel flow, so perhaps it is the power changes that create the errors. Without a flow bench, it's hard to tell. Flowscan does not specify accuracy other than steady state.

Skip

A while ago I cut a Floscan transducer open to see what is inside.

Clarence

[hypertech]

There are smarter people than me when it comes to definitions of psychology, but is this really expectation bias?  Expectation bias would be, I put the gear handle down, I did a GUMPS check and I expected the light to be out because its burnt out.  However, the gear actually failed to deploy but I didn't know because I expected the light to be out.

On the other hand, you just got distracted on final and forgot to put the gear down or do a GUMPS check.  Expectation bias doesn't really come into it - it just wasn't done.  With an indicator out, I don't know how you do a GUMPS check without looking at the handle and/or the floor.

[jetdriven]

18 hours ago, Will.iam said:

Yes that is true until you forget to switch at the top of descent and now that “verify” which I’m advocating at gear down allows me to catch missing the switch at the top of descent sort of like missing the word verify and thinking you saw switch in my original comment. 

Yes, thanks for the correction. Its a great idea.

[carusoam]

+1 for additional memory devices… like skip mentioned.

If I have something I need to remember… because it is upcoming, and I can’t execute it now….  And it’s minutes away… long enough that it has a high likelihood of not be executed in a timely manner….

My hand gets placed in an uncomfortable location… the glare shield.

When ATC gives you a new altitude… and it’s a few minutes away…  don’t put your hand down until you have begun leveling off….  

When you catch yourself putting your hand down… and you haven’t reached the new altitude yet…. You will probably start laughing because it is really difficult being human….  

 

Note for skip… an easy way to un port the fuel pick-ups…. Lower the nose.

When the nose gets lowered on final approach… that is enough of a slope to have what little fuel in the tanks slosh forwards away from the pick-up….

M20C experience…

Something I learned on a maintenance flight around the pattern…. Both tanks had a few gallons of fuel in them…. Both indicators read close to empty. On short final things got quieter than usual…. Flip the selector switch, it takes a few seconds to get fuel into the carb’s bowl… power comes back quickly…

Learned two things on that flight… New generator was working perfectly… fuel moves a long distance when you drop the nose…

 

 

Note for anyone afraid to change tanks at any time… practice on the ground… it doesn’t change in the air…. 
 

MS has had a couple of selector switches bind up over the years… They don’t fail without giving plenty of heads-up… 

So… if your selector switch isn’t working smoothly… that can be OH’d before it sticks half way between tanks…. 
 

 

About those low level fuel indicators… it really helps to know how much usable fuel you have left…

For new owners…

1) Learn how much fuel you have available in each tank…

2) Get your K-factor squared away…

3) Get your Low fuel level warning calibrated…  Some older LBs had the same warning set-up as the M20Js…  it was nearly enough for the M20J FFs… not nearly enough for a 280hp M20R…

4) Essentially the Low fuel level warning gives you enough time to get to a good field…  you don’t want it set up to tell you land now! 

5) With a decent calibration of the fuel totalizer, or having a decent calibration of the Ceis FL indicators… the low level fuel warning is a bit extraneous, until you really need it…

Old PP memories, plenty of fuzz on them…. Details may be inexact…

Best regards,

-a-

[A64Pilot]

Fuel wise, I log fuel burned from each tank on my knee board when I switch tanks, I usually burn 2/3 from a tank and switch, I plan to switch once in a flight.

Do not rely on those gauges and or low fuel lights, I promise you if you do one day they will let you down.

In cave diving we have a rule of thirds, it means you breathe no more then 1/3 of your gas on the way in, leaving 1/3 for the way out and 1/3 reserve.

I follow the rule of thirds flying too, meaning I don’t plan on burning more than 2/3’s of my fuel, not saying I never do, unforcasted winds, ATC reroutes etc happen, but if you follow the rule of thirds, gas won’t  be a stressor.

Edited September 14, 2021 by A64Pilot

[steingar]

Expectation bias is thinking you've lowered the gear and trying to get the facts to fit your hypothesis.  I had the opposite happen once.  Got a bit jangled on my takeoff by something, and took off flying a hundred miles an hour.  I knew something was amiss, airplane is far faster than that.  I checked what engine readings I could, checked power settings, made certain the door and luggage door were closed.  I then looked down, saw the bar in the panel and realized my gear was still down.

[KB4]

On 9/12/2021 at 5:24 PM, carusoam said:

You have gone on what looks like an attack of the one guy who knows repair of GU landings as well as anyone on the planet…

No, he was trolling me unnecessarily.  That’s all.  Whereas I am trying to help others. 

[carusoam]

 

@KB4

I’m Not sure how trolling happens on MS… necessary or unnecessary…

But I’ll keep an eye out for it…

Reporting it is pretty easy as well…

Best regards,

-a-