Report out on 231 crash

[Pritch]

 

[carusoam]

Heads-up... old accident, not recent...

i simply mis-understood Pritch’s title... (I must be getting gun shy)

Woodlands State Airpark, WA

April 21, 2016...

N97119

-a-

[kortopates]

I think Anthony meant, old accident, but new video. The final was actually out Sept 2018.

The report: https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20160421X94028&AKey=1&RType=HTML&IType=FA 

Seriously? "When asked where he obtained the EW of 1,804 lbs, the pilot replied that he retrieved this EW from the internet.

That was only one of several issues that led to this fatal including one sick engine with mags mistimed by 8 degrees, governor incorrectly set  and insufficient FF which all conspired to limit takeoff RPM to 2430 rpm - which is 270 rpm low! 

But as they say about all accident, its takes several mistakes or issues to all align to allow an accident, any of which if removed will likely prevent it. In this accident, if the pilot had briefed an emergency takeoff briefing including an abort point down the runway,  this accident would have been prevented. 

I hope anyone still not doing an takeoff emergency brief that includes the abort point for takeoff realizes how dangerous that can be departing from any marginal field. However, you have to do it for every takeoff to build the discipline to always do it. But the excerpt quoted from the Flying handbook by identifying the point where you expect to be airborne and then aborting there if not off is too late; especially true in this case or you wouldn't even try to take off on this runway following that rule. The 50/70 rules is much safer and realistic way to do it and usually easier way to do it. Easier since there is typically something by the midpoint you can identify before the takeoff run to use to call abort.  ( I don't think its realistic to judge when for example you come to 1250' of runway used as this pilot calculated for this takeoff.) This simple rule though is based on seeing your IAS airspeed reach 70% of rotate speed by 50% of the runway and then aborting if not, while you still have ample room to stop.  Especially this time of year with high density altitude takeoff being much more common place is a good time to make it a habit. Here is a good quick article on it https://www.boldmethod.com/learn-to-fly/performance/how-to-use-the-50-70-rule-of-thumb-for-your-takeoff-this-summer/ 

Edited July 1, 2019 by kortopates

[kmyfm20s]

I was surprised that it was the back seat passenger that lost his life even though he didn’t have his shoulder belt on. Just shows you how important they are!

[aviatoreb]

That is quite a hit that airplane took.  It is tragic but maybe not that terribly surprising.  

I was always suspicious of school buses since those yellow school buses have no seat belts.  They call it the "egg carton" theory where there is so little space to move around that our precious little eggs - the little children are safe since there isn't a lot of place for them to move in an accident. I think more so it sort of works since in most accidents a yellow school bus is much more massive than a car it might hit.

[Mooney in Oz]

Man that was shocking to watch.  I used the same vocabulary in unison with the man filming when the aircraft struck the fence and berm.

Only 4 topics and I have already learnt a fair bit from what I have read, particularly from this thread. I admit to previously not taking much notice of the 50/70 rule, which I will be implementing at every takeoff from now on after viewing the video.  I have aborted takeoffs before, but only from a 'seat of the pants' feel.

Thanks Pritch for sharing.

I also want to thank Craig @mooniac58 and any others who were instrumental in creating this new forum.

[PT20J]

On 7/1/2019 at 1:43 PM, kortopates said:

I think Anthony meant, old accident, but new video. The final was actually out Sept 2018.

The report: https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20160421X94028&AKey=1&RType=HTML&IType=FA 

Seriously? "When asked where he obtained the EW of 1,804 lbs, the pilot replied that he retrieved this EW from the internet.

That was only one of several issues that led to this fatal including one sick engine with mags mistimed by 8 degrees, governor incorrectly set  and insufficient FF which all conspired to limit takeoff RPM to 2430 rpm - which is 270 rpm low! 

But as they say about all accident, its takes several mistakes or issues to all align to allow an accident, any of which if removed will likely prevent it. In this accident, if the pilot had briefed an emergency takeoff briefing including an abort point down the runway,  this accident would have been prevented. 

I hope anyone still not doing an takeoff emergency brief that includes the abort point for takeoff realizes how dangerous that can be departing from any marginal field. However, you have to do it for every takeoff to build the discipline to always do it. But the excerpt quoted from the Flying handbook by identifying the point where you expect to be airborne and then aborting there if not off is too late; especially true in this case or you wouldn't even try to take off on this runway following that rule. The 50/70 rules is much safer and realistic way to do it and usually easier way to do it. Easier since there is typically something by the midpoint you can identify before the takeoff run to use to call abort.  ( I don't think its realistic to judge when for example you come to 1250' of runway used as this pilot calculated for this takeoff.) This simple rule though is based on seeing your IAS airspeed reach 70% of rotate speed by 50% of the runway and then aborting if not, while you still have ample room to stop.  Especially this time of year with high density altitude takeoff being much more common place is a good time to make it a habit. Here is a good quick article on it https://www.boldmethod.com/learn-to-fly/performance/how-to-use-the-50-70-rule-of-thumb-for-your-takeoff-this-summer/ 

Preplanning an abort point is an excellent idea. The first time I ran across the 50/70 notion was in the late Sparky Imeson's excellent Mountain Flying book back in the 80's. However, I did some calculations (attached) and I don't think this is conservative enough. First, assuming constant acceleration, 70% of lift off speed at the midpoint gets you to lift off speed at the very end of the runway. This doesn't allow for any margin and it also doesn't allow for any obstacles whatsoever. Also, the assumption of constant acceleration is probably generous. The propeller thrust is highest when standing still and decreases with increasing speed, and the aerodynamic drag, zero when standing still, will increase with increasing speed. Perhaps 80% of lift off speed at the mid point would be a better choice, unless there is a headwind (the calculations assume calm wind).

Skip

50-70_20190704_0002.pdf

 

[xcrmckenna]

My normal call out is 60 at 1000. I want to be doing 60 miles an hour at the 1,000ft mark. It’s pretty conservative but if I’m heavy it will take a lot of runway to stop if I’m doing the 50/70 rule.


Sent from my iPhone using Tapatalk

[carusoam]

Brief review of some key facts...

M20K...

Fully loaded... MGTW.

2k’ of runway

Temp in the. Mid 70s °F

Expected T/O roll is more than halfway down the runway... roughly 1,300’

 

Then add the unaccounted for challenges...

Plane exceeded MGTW

Prop wasn’t turning anywhere near max RPM.  2430 instead of 2700...

Mag timing ensured not making full power...

 

Result...

Plane used most of the entire runway before attempting the lift-off...

There was no room for abort/stop.

 

 

To have this plan be successful, requires to know...Plane’s T/O roll when...

Loaded this way

Mags timed this way

Same weather conditions 

Prop limited this way

 

Having a recent baseline of performance of the plane can be very helpful to not fall for this challenge...

Prove the plane is making book numbers first... before moving on to max performance T/O with no room to spare...

Three checks I use for every T/O... MP, RPM, FF... before Airspeed alive... (don’t get bogged down collecting data)

this T/O would have been rejected early on... FF and RPM would be strong hints of why the plane isn’t going to be leaving the ground as expected... At the halfway point it is awfully late to be doing math holding some unexpected numbers...

If you find yourself outside the POH envelope... it is better to collect some data solo, than with friends...

 

Data collection can come from a WAAS source and CloudAhoy...

See how long your actual T/O rolls really are...

Climb rates will also give you a hint to how well things are working, horsepower wise...

 

Changing 200 RPM can easily drop 10% of the expected hp... extending the distance required 50%...

Repeat (because it is important)..., small change in HP = Long change in T/O roll...

 

PP thoughts on avoiding another similar tragedy... know b4Ugo...

PP thoughts only, not a CFI or mechanic...

Best regards,

-a-

 

 

[kortopates]

4 hours ago, PT20J said:

Preplanning an abort point is an excellent idea. The first time I ran across the 50/70 notion was in the late Sparky Imeson's excellent Mountain Flying book back in the 80's. However, I did some calculations (attached) and I don't think this is conservative enough. First, assuming constant acceleration, 70% of lift off speed at the midpoint gets you to lift off speed at the very end of the runway. This doesn't allow for any margin and it also doesn't allow for any obstacles whatsoever. Also, the assumption of constant acceleration is probably generous. The propeller thrust is highest when standing still and decreases with increasing speed, and the aerodynamic drag, zero when standing still, will increase with increasing speed. Perhaps 80% of lift off speed at the mid point would be a better choice, unless there is a headwind (the calculations assume calm wind).

Skip

50-70_20190704_0002.pdf 72.29 kB · 4 downloads

 

Good job showing ~70% Vref is at 1/2 the distance. But yes, there is no margin and this isn't a substitute for not checking required runway to get airborne and to clear obstacles if there are any, before we take the runway for departure. But I think its natural to add some buffer in the required speed, i.e. my 70% speed of Vref at max gross is 47 kts, which I can't really read off the IAS anyway so it gets translated to 50 kts as I scan. But what this really does is help us to identify an abort point midway down the runway with still enough room to get stopped since our stopping distance is less than our takeoff distance. But adding another 10% margin is a good idea too. Its waiting till when we are suppose to liftoff, or worse past that point, on a marginal runway and find we're out of options is what causes these accidents. 

Incidentally, in the accident report the pilot says he calculated ~1250' roughly for takeoff yet my 252 POH shows roughly 1500' at 2900 lbs.  

[GeeBee]

The report said the airplane had a "normal runup". There is no way mags mistimed by 8 degrees had a "normal runup". The pilot likely ignored poor mag performance. I am surprised the investigator took that testimony on face value.

[Niko182]

On 7/4/2019 at 8:47 PM, kortopates said:

Good job showing ~70% Vref is at 1/2 the distance. But yes, there is no margin and this isn't a substitute for not checking required runway to get airborne and to clear obstacles if there are any, before we take the runway for departure. But I think its natural to add some buffer in the required speed, i.e. my 70% speed of Vref at max gross is 47 kts, which I can't really read off the IAS anyway so it gets translated to 50 kts as I scan. But what this really does is help us to identify an abort point midway down the runway with still enough room to get stopped since our stopping distance is less than our takeoff distance. But adding another 10% margin is a good idea too. Its waiting till when we are suppose to liftoff, or worse past that point, on a marginal runway and find we're out of options is what causes these accidents. 

Incidentally, in the accident report the pilot says he calculated ~1250' roughly for takeoff yet my 252 POH shows roughly 1500' at 2900 lbs.  

Thats also with a plane that has 10 more hp than the aircraft in the accident. Also wondered if he factored in about 10 to 20 feet for the hill.

[steingar]

Anytime I land or take off from a less than stellar field I always stay light.  We're all human, and you haven't much room to get the airplane stopped even if you realize right away that something is amiss.  It takes a second or two for the human brain to register.

[kortopates]

22 hours ago, Niko182 said:

Thats also with a plane that has 10 more hp than the aircraft in the accident. Also wondered if he factored in about 10 to 20 feet for the hill.

The 252 and 231 have same HP, its the Encore with 10 more HP. 

I doubt the pilot factored in the 9' berm, since its 410' past the departure end of the runway. Wouldn't have been a factor if all was working properly.

Total Distance from threshold to berm was 2363' which was enough distance to clear a 50' obstacle with 4 kt head wind, but with the calm winds he had, (per NTSB) the POH had a him a bit short of that but still sufficient to clear it if the plane was capable of making near book power - which it obviously wasn't.

[Ragsf15e]

When flying a 30 year old (or in my case, 51 year old) airplane, I tend to be very conservative on performance planning.  Like if my poh takeoff or landing distance is more than 50% of available runway, I will reconsider my plan.  Does reconsider limit my destinations? Sometimes.  Does it necessarily mean I won’t do it? No.  Does it mean I’ll change my fuel and passenger load? Definitely.  Time of day (temp)? Definitely.

If you’re counting on making book values to perfection, it will eventually catch up with you.

[Hank]

7 hours ago, Ragsf15e said:

If you’re counting on making book values to perfection, it will eventually catch up with you.

Regardless of aircraft type or age. 

Also applies to non-aircraft  machines, vehicles and equipment.  Expecting perfect results will end in disappointment sooner or later, and may well be due to operator error as much as equipment failure.

Edited August 28, 2019 by Hank

[airmocha]

Flying my dad's AA1 Yankee from Missouri to California in 1988 taught me that, in almost every type aircraft (normally aspirated), if your takeoff runway isn't at least as long as your density altitude, best be thinking very clearly of doing something other than taking off at max gross weight in calm wind.

I used almost every foot of the longest runways in Santa Fe and Winslow trying to coax that thing out of ground effect.

Guardian angels...

[Andy95W]

13 hours ago, airmocha said:

 if your takeoff runway isn't at least as long as your density altitude, best be thinking very clearly of doing something other than taking off at max gross weight in calm wind

That is one of the best and easiest to remember rules of thumb I've never heard before.  Thank you.

[carusoam]

Follow-up insight on Rejected Take-Offs (or Aborts)... regarding this incident....

Somebody decided to cover the RTO issue in a step by step manner...

Nothing new that isn’t covered here already...

But a sure reminder regarding MP and RPM not matching expectations...

Best regards,

-a-

 

 

[Missile=Awesome]

I am a sound and out the window pilot on short final and take-off roll.  I started confirming rpm/mp as a result of this video when it first came out.

I don’t land at runways <3k’.  My personal minimum.

I didn’t previously do a final confirmation of “killers” Mixture/Trim just prior to taking the runway.  Who hasn’t become distracted and started rolling with mixture still pulled for ground ops?  I know I have...

Accidents are often a chain of events or dominos that breaking the chain will prevent the occurrence or lessen the severity.  I have NEVER investigated an “Act of God” incident.  There was ALWAYS lessons learned to prevent a future scenario from resulting in personal injury or property damage.

Instruction like this is excellent.  To watch again is “not a waste of time”.

[neilpilot]

15 minutes ago, Missile=Awesome said:

Who hasn’t become distracted and started rolling with mixture still pulled for ground ops?  I know I have...

I lean severely for ground ops, so the engine will stumble or quit when the throttle is advanced before I even get to the runway.  So it's virtually impossible for me to attempt a departure leaned for ground ops.

[Yetti]

5 hours ago, Missile=Awesome said:

I am a sound and out the window pilot on short final and take-off roll.  I started confirming rpm/mp as a result of this video when it first came out.

I don’t land at runways <3k’.  My personal minimum.

I didn’t previously do a final confirmation of “killers” Mixture/Trim just prior to taking the runway.  Who hasn’t become distracted and started rolling with mixture still pulled for ground ops?  I know I have...

Accidents are often a chain of events or dominos that breaking the chain will prevent the occurrence or lessen the severity.  I have NEVER investigated an “Act of God” incident.  There was ALWAYS lessons learned to prevent a future scenario from resulting in personal injury or property damage.

Instruction like this is excellent.  To watch again is “not a waste of time”.

The mixture should go up prior to the mag check.  Otherwise it will die.  which will start the mag check at the end of the flight vs right before the flight.  But you should cycle to prop.... before flight.

[Yetti]

I clicked through the video.   There is too much emotional stuff in it "feeling in his stomach that he hurt his friends"    What he should be saying is half way back up the runway they pilot should have know something was wrong and cut the power.    How do you know that how do you train for that decision.

[Missile=Awesome]

2 hours ago, Yetti said:

The mixture should go up prior to the mag check.  Otherwise it will die.  which will start the mag check at the end of the flight vs right before the flight.  But you should cycle to prop.... before flight.

I do mag check/prop cycle before taxi at hanger...

[Mooney in Oz]

8 hours ago, neilpilot said:

I lean severely for ground ops, so the engine will stumble or quit when the throttle is advanced before I even get to the runway.  So it's virtually impossible for me to attempt a departure leaned for ground ops.

Also demonstrates the importance of a 'Line Up' checklist.