M20F crash Carrizozo NM 8/2/24

[Mooney in Oz]

Luckily, no injuries.

The aircraft lifted off the runway, encountered a strong downdraft and crashed off the end of the runway into a fence. No injuries. 

https://asn.flightsafety.org/wikibase/407627

[Shadrach]

Glad there were no injuries. Very sorry to see another 1967 Exec destroyed.

[DCarlton]

Density Altitude plus downdraft?  

[Shadrach]

On 8/8/2024 at 12:24 AM, DCarlton said:

Density Altitude plus downdraft?  

DA was ~8000.. properly leaned, his take off FF should have been just a bit over 15gph. 5000’ seems like a lot of runway for an F model but I can envision a scenario where it isn’t and this one has many of those components 

corrected for cut and paste error

[Fly Boomer]

7 hours ago, Shadrach said:

DA was ~12,500

Wow!  I didn't see that in the report.  Is that a calculation?

[1980Mooney]

3 hours ago, Fly Boomer said:

Wow!  I didn't see that in the report.  Is that a calculation?

Not sure where this is coming from.

The accident happened in Carrizozo, New Mexico at the Municipal Airport, F37.  Field elevation is 5,373 ft.  The weather in the prelim report is from 22 naut. miles away at Rudioso Airport (Sierra Blanca KSRR) which is at a higher elevation, 6,810 ft.

Like a lot of New Mexico, desolate Carrizozo (population 973) is in the middle of nowhere.  There is no online weather from Carrizozo - look closely, they all report outside Ruidoso at KSRR - even the National Weather Service and ForeFlight.  There is no METAR from F37.  Since it happened at about 1 PM, it was probably about 90-95 degrees F and like most of New Mexico dry as hell with low dew point.  I would estimate that density altitude was about 8,800 ft. 

Winds at Carrizozo that day?  Who knows - the reporting at KSRR, located on a mountain valley north east of Ruidoso, is separated from Carrizozo by the Sierra Blanca Mountains, 11,981 ft.  It is questionable if the wind conditions at KSRR were anything like Carrizozo at that time.

The area around Carrizozo Airport is barren and flat - It is not like Sierra Blanca (Ruidoso) KSRR which is more rugged surrounded by drop offs and valleys- and more prone to shifting wind drafts.

This might be a case of a  Mississippi based flatlander getting messed up by density altitude.  However 2 weeks before he had flown in and out of Sedona without incident. - granted not in the middle of the hot afternoon.

 

Edited August 8, 2024 by 1980Mooney

[Shadrach]

6 hours ago, Fly Boomer said:

Wow!  I didn't see that in the report.  Is that a calculation?

Edit: looks like wunderground give the pressure setting and not the altimeter setting. I should have caught that. I will rework the numbers after dinner. 
 

The calculated DA from the prelim was just under 8000’.

[PT20J]

There really aren’t downdrafts that close to the ground because the air cannot go through the ground plane. But, there can be windshears. 

[1980Mooney]

1 hour ago, Shadrach said:

Sort of.  It's not exact.  I interpolated by calculating the DA at Roswell (KROW) which is 70NM east.  It was the closest station with historical weather.

Roswell's numbers at 12:51pm:

Temp: 94

Altimeter: 26.48

Field elevation: 3671'

Pressure Altitude: 7127

Density Altitude: 10,284'

An hour later at 1:51pm the DA at Roswell had increased to 10,569'

The accident was at 1:11PM at Carrizozo, which is at 5,373msl or 1,700' higher than Roswell.  Perhaps the DA was not quite 12,500' but it was likely close enough as makes no difference.

 

Except that you’re using an altimeter setting/barometric pressure (26.48) that is  lower than has ever been recorded anywhere on earth.  I used Standard.  The Prelim report says that at Ruidoso/Sierra Blanca it was 30.5 at the time which means the actual density altitude might’ve even been another 5 to 600 feet lower and closer to 8300 feet.  

The barometric pressure reading at Roswell must’ve been an error. Hey it’s New Mexico – things don’t always work right. Garbage in gives you garbage out.

“The lowest barometric pressure ever recorded in the continental United States (CONUS) for a non-tropical system at sea level is 28.20 inHg (955.0 millibars), which occurred twice in US history:”

Edited August 8, 2024 by 1980Mooney

[Shadrach]

38 minutes ago, 1980Mooney said:

Except that you’re using an altimeter setting/barometric pressure (26.48) that is  lower than has ever been recorded anywhere on earth.  I used Standard.  The Prelim report says that at Ruidoso/Sierra Blanca it was 30.5 at the time which means the actual density altitude might’ve even been another 5 to 600 feet lower and closer to 8300 feet.  

The barometric pressure reading at Roswell must’ve been an error. Hey it’s New Mexico – things don’t always work right. Garbage in gives you garbage out.

“The lowest barometric pressure ever recorded in the continental United States (CONUS) for a non-tropical system at sea level is 28.20 inHg (955.0 millibars), which occurred twice in US history:”

Yes, you’ll note I edited the post,  ‘twas a brain fart on my part

[PT20J]

1 hour ago, Shadrach said:

‘twas a brain fart on my part

OK, now we are going to call you Rhymin' Ross 

[Shadrach]

16 minutes ago, PT20J said:

OK, now we are going to call you Rhymin' Ross 

I’ve had much less flattering monikers in my life!

[cliffy]

Have been to F37 in my D model

Didn't leave anything there that I had to go, back for!  :-)

They did however have cheap fuel when I was there but little else.

The "crew car' if it can be called that was a broken down rusty old PU the ran on 6 out of 8 cylinders. 

Got to fly around the restricted area to get in there. 

[Utah20Gflyer]

On 8/8/2024 at 4:15 AM, Shadrach said:

DA was ~8000.. properly leaned, his take off FF should have been just a bit over 10gph. 5000’ seems like a lot of runway for an F model but I can envision a scenario where it isn’t and this one has many of those components 

corrected for cut and paste error

CHTs would be super high at that fuel flow.   One of the challenges of high DA takeoffs in an older Mooney like mine is a fuel flow that keeps engine temps reasonable also leaves a lot of potential power unused.  
 

Now, having said that even my plane with 20 less hp can take off with plenty of safety margin at that DA - if things are done correctly.  The key is to keep the plane as light as possible (1 person, half tanks)  You have to lean as much as possible (heat limited) and accept that CHTs are going to exceed 420+ degrees.  
 

We don’t have any details about what happened but Full fuel in an F would be a lot of extra weight.  The one person, full fuel and a bunch of baggage could be excessive for those conditions. 
 

Full rich or excessively rich on takeoff would rob the engine of a lot of power could have been an issue.  But we don’t know.  
 

Could the crash be solely caused by a down draft?  Possibly,  but I suspect it was only the last straw.  
 

I’m really glad the pilot was Ok!  

[Ragsf15e]

30 minutes ago, Utah20Gflyer said:

CHTs would be super high at that fuel flow.   One of the challenges of high DA takeoffs in an older Mooney like mine is a fuel flow that keeps engine temps reasonable also leaves a lot of potential power unused.  
 

Now, having said that even my plane with 20 less hp can take off with plenty of safety margin at that DA - if things are done correctly.  The key is to keep the plane as light as possible (1 person, half tanks)  You have to lean as much as possible (heat limited) and accept that CHTs are going to exceed 420+ degrees.  
 

We don’t have any details about what happened but Full fuel in an F would be a lot of extra weight.  The one person, full fuel and a bunch of baggage could be excessive for those conditions. 
 

Full rich or excessively rich on takeoff would rob the engine of a lot of power could have been an issue.  But we don’t know.  
 

Could the crash be solely caused by a down draft?  Possibly,  but I suspect it was only the last straw.  
 

I’m really glad the pilot was Ok!  

I agree with you about that ff being too low.  Usually Ross is correct on these engine questions 100% of the time, so i was doubting myself, but it’s definitely higher than 10.  I would think even 100ROP would be slightly higher (maybe 11gph?) and as you said, cooling is key.  I use target egt for my high DA altitude takeoffs and that leaves me around 200 ROP which seems to be a reasonable compromise between cooling and power. I’d guess around 13-14 gph at that DA, but I’ll check my engine data as I took off at a very similar DA just last month in MMH (so yes, it should do it just fine unless there’s mitigating factors).

[Shadrach]

 

@Utah20Gflyer and @Ragsf15e

Gents,

I pooched all of my posts in this thread royally....  I originally cut and pasted historical weather from wunderground weather into an online E6B not bothering to see that wunderground was giving station pressure, not altimeter setting. (Duh...26.68” is not possible).  I came up with an approximate DA of 12,500ish (again duh).  The 10gph figure is what my POH show for best power at 12,500'  I went back and amended all of the mistakes but neglected to amend the FF which should have been leaned to ~ 15.5gph.  I have edited the previous post.

It's been a long week for me and I am showcasing it in some of my posts...

[DCarlton]

For folks without fuel flow meters, what's the best procedure for leaning in this situation?  I know this has been discussed many times.  Take your peak EGT at sea level and make it 100 deg rich of that?  I end up adding a twist or two richer than that just because it "feels" better.  Never confident I'm making best power.  

[1980Mooney]

13 hours ago, cliffy said:

Have been to F37 in my D model

Didn't leave anything there that I had to go, back for!  :-)

They did however have cheap fuel when I was there but little else.

The "crew car' if it can be called that was a broken down rusty old PU the ran on 6 out of 8 cylinders. 

Got to fly around the restricted area to get in there. 

The plane left Mississippi June 9 and stopped near Las Cruces, New Mexico for a few days and then Sedona, Arizona.  Looks like he was on the way back when he landed at Carizzozo on July 21.  He was there over a week and a half.  There is nothing to do in Carrizozo for that long unless you are going hiking/backpacking in the nearby Lincoln National Forest.

I wonder if his plane broke down.

18 hours ago, PT20J said:

There really aren’t downdrafts that close to the ground because the air cannot go through the ground plane. But, there can be windshears. 

 

56 minutes ago, Shadrach said:

 

@Utah20Gflyer and @Ragsf15e

Gents,

I pooched all of my posts in this thread royally....  I originally cut and pasted historical weather from wunderground weather into an online E6B not bothering to see that wunderground was giving station pressure, not altimeter setting. (Duh...26.68' is not possible)  I came up with an approximate DA of 12,500ish (again duh).  The 10gph figure is what my POH show for best power at 12,500'  I went back and amended all of the mistakes but neglected to amend the FF which should have been leaned to ~ 15.5gph.  I have edited the previous post.

It's been a long week for me and I am showcasing it in some of my posts...

You may have noticed that the owner got his Commercial ticket in 6/2022 with Glider privileges.  And he had an Instructor MEI rating 8/2021 that expired 8/2023.  Interestingly the FAA shows his last Medical was 5/2015 with no BasicMed.  He bought the Mooney in July 2021.  Knowing about density altitude, leaning and wind should not be a big challenge for a Glider rated MEI if he was flying.

 

[N201MKTurbo]

When I bought my first Mooney which was an M20F in 1984, I flew every day for work. I was a field service engineer for Raytheon Data Systems and we had equipment all over the place. They let me fly my plane to do service calls. I was based in Denver and flew all over Colorado, new Mexico, Wyoming, South Dakota and Nebraska. I flew in all kinds of weather including high winds. Sometimes crazy strong winds. I was flying about 700 hours a year back then. I always considered an airport at 5000 feet elevation a low elevation airport. The M20F never had any issues taking off from those airports. My Home drome back then was at 5400 feet and was only 4000 feet long. Never an issue. I'm not saying that there wasn't some crazy wind, or dust devil or who knows. but normally the plane would be airborne half way down a 5000 foot runway and would be climbing at 500 FPM or so. He should have been a few hundred feet AGL by the end of the runway. There must have been something else going on here.

[A64Pilot]

43 minutes ago, DCarlton said:

For folks without fuel flow meters, what's the best procedure for leaning in this situation?  I know this has been discussed many times.  Take your peak EGT at sea level and make it 100 deg rich of that?  I end up adding a twist or two richer than that just because it "feels" better.  Never confident I'm making best power.  

Power drops off pretty slowly when ROP when enriching, but very quickly if LOP.

In my opinion I like being well ROP of 100F ROP, I know it’s best power but at low air speeds in a climb it’s going to get hotter than I like.

Again an opinion but I think your doing the right thing.

[A64Pilot]

19 hours ago, PT20J said:

There really aren’t downdrafts that close to the ground because the air cannot go through the ground plane. But, there can be windshears. 

I’m not so sure.

Years ago an AH-64 was slapped to the ground during gunnery training at Ft Rucker from a down burst, front seater was killed from memory, they were most likely at about a 100’ hover. That was roughly 1987 so I can’t find anything 

I personally was slapped by a down draft at Ft Stewart and overtorqued the snot out of it to stop the crash. I was maybe 50 foot above the trees. The Maintenance Data Recorder that recorded literally everything showed a sudden about 40 kt crosswind right after I pulled collective until the low RPM audio went off.

Both times Thunderstorms were near by

 

[Shadrach]

52 minutes ago, DCarlton said:

For folks without fuel flow meters, what's the best procedure for leaning in this situation?  I know this has been discussed many times.  Take your peak EGT at sea level and make it 100 deg rich of that?  I end up adding a twist or two richer than that just because it "feels" better.  Never confident I'm making best power.  

Some recommend leaning during a static run up for best power. Some just twist the knob out during the initial roll until they “feel” the engine hit max power. One could also consult the POH which will give you max RPM, max power fuel flow for a given altitude. It won’t be dead, solid, perfect but it will get you close.

[Ragsf15e]

3 hours ago, Shadrach said:

Some recommend leaning during a static run up for best power. Some just twist the knob out during the initial roll until they “feel” the engine hit max power. One could also consult the POH which will give you max RPM, max power fuel flow for a given altitude. It won’t be dead, solid, perfect but it will get you close.

You will get max power but you’ll get real hot chts real fast too.  I use the target egt from a sea level full rich takeoff.  It’s probably ~200 rop, but it’s close enough to max power and it won’t cook the engine during the initial climb.
 

@DCarlton, on a sea level takeoff at full rich, note your egt (probably low 1200s).  On a high DA takeoff just lean to that same egt, then you keep leaning to hold that egt as you climb.  It’s a reasonable setting and you can adjust richer if needed for cooling on really hot days.

[Ragsf15e]

5 hours ago, Shadrach said:

 

@Utah20Gflyer and @Ragsf15e

Gents,

I pooched all of my posts in this thread royally....  I originally cut and pasted historical weather from wunderground weather into an online E6B not bothering to see that wunderground was giving station pressure, not altimeter setting. (Duh...26.68” is not possible).  I came up with an approximate DA of 12,500ish (again duh).  The 10gph figure is what my POH show for best power at 12,500'  I went back and amended all of the mistakes but neglected to amend the FF which should have been leaned to ~ 15.5gph.  I have edited the previous post.

It's been a long week for me and I am showcasing it in some of my posts...

Ha! It happens to us all.  I just climbed through 9000’ DA and checked my ff at target egt was 14gph so your new guesstimate makes more sense.

Im just glad @Utah20Gflyer was willing to call you on it because I was really doubting myself as your engine knowledge is typically spot on!

[DCarlton]

3 hours ago, Ragsf15e said:

You will get max power but you’ll get real hot chts real fast too.  I use the target egt from a sea level full rich takeoff.  It’s probably ~200 rop, but it’s close enough to max power and it won’t cook the engine during the initial climb.
 

@DCarlton, on a sea level takeoff at full rich, note your egt (probably low 1200s).  On a high DA takeoff just lean to that same egt, then you keep leaning to hold that egt as you climb.  It’s a reasonable setting and you can adjust richer if needed for cooling on really hot days.

I'll have to pay more attention and write it down but I think I'm seeing highs in the 1390s.  Not sure if that's at sea level though.  Interestingly I'm hoping to get from SOCAL to ELP through NM in a week or so; monsoon season permitting.