Cruising at 17,500 in a M20J

[EricJ]

48 minutes ago, Pinecone said:

At 25,000, I have noticeable symptoms, but can perform for longer than the chamber guys wanted to wait.  But I can tell.

It was the same for me in the PROTE exercise.   I can generally tell when I'm impaired, but I was still somewhat functional but impaired even at the end of the exercise.   They limit your max time since they don't want you to pass out, they said because they want you to remember the exercise and your symptoms. 

In the vid of the Kalitta Learjet, where they lose pressure at a pretty high altitude, the pilot stays conscious and just functional enough to eventually get them out of it with some help.   The co-pilot was AWOL until they got to lower altitude and then came back pretty strong.    It's an interesting view into differences in different people's susceptibility.   The big lesson I got out of the PROTE exercise was how varied it is for different people.   17k might be very low risk for some people, and much higher for others.
 

 

[LANCECASPER]

46 minutes ago, A64Pilot said:

I don’t remember how high we went, but I’ve been to Fl 250 in a crop duster, does that count?  

The corn must have been tall that year 

[Pinecone]

Did a flight with two friends who were both pilots.  C-182.  I was left seat, guy in the right seat was under the hood flying (working on CFII), and third in the back. 

Due to being ON the day of the chart change over and not having current charts, we were VFR, but had to go to 13,500 for a short ways to clear some cloud tops.  I noticed the guy in the right seat head was moving about a lot and his flying had deteriorated.  I looked back and the guy in the back was OUT.

Over the clouds and back down to 9,500, right seat guy was rock solid and guy in the back woke up.

 

[Ragsf15e]

Age can make you more susceptible…

[haymak3r]

17 hours ago, Shadrach said:

@haymak3r your best bet at that altitude is to set the richest cylinder at whatever setting is the smoothest between peak and 100ROP.

I was trying. it was not a very small change in just a slight rotation of the control. Not like down lower. I definitely want to try this again, and this time file a plan to get in to the flight levels. This was a just for fun experiment, so didn't bother. It was a good learning opportunity though.

[haymak3r]

11 hours ago, ArtVandelay said:

I did this years ago, according to the POH the ceiling is 23,000’ for a J loaded to 2300 lbs, but I was struggling to get to 17000’ Turned out my cam was bad and wasn’t making power in 2 cylinders, ended up overhauling it but haven’t tried it since.
Im basicmed so now I’m legally limited to below 18000’.
BTW, OP’s speeds are in mixed units, GS in knots and TAS in mph…I would change that and make them both knots.

I have tried /sigh. I trained with all the original instruments, and so memorized everything in mph.. So when I had the g5's and everything else installed, I DID have GS in mph, and my oat in deg. F. But, flight planning wasn't as easy, and so it's easier for me at least to have GS in kts, and my temp in deg. C. I also am still stuck with my paper checklists. Even though I have already created digital ones for both my gtn 750, and in foreflight lol. 

[haymak3r]

4 hours ago, Pinecone said:

That is why everyone who goes into the teens or higher REALLY needs to do a chamber ride.  Either a real pressure chamber or the travelling one that simulates by lower O2 %.

At 25,000, I have noticeable symptoms, but can perform for longer than the chamber guys wanted to wait.  But I can tell.

I would absolutely love to give this a try sometime.

[Shadrach]

4 minutes ago, haymak3r said:

I was trying. it was not a very small change in just a slight rotation of the control. Not like down lower. I definitely want to try this again, and this time file a plan to get in to the flight levels. This was a just for fun experiment, so didn't bother. It was a good learning opportunity though.

Makes sense. Minimal amount of air available but mixture changes are happening at the same scale as the are at low altitude.

[Shadrach]

3 hours ago, EricJ said:

It was the same for me in the PROTE exercise.   I can generally tell when I'm impaired, but I was still somewhat functional but impaired even at the end of the exercise.   They limit your max time since they don't want you to pass out, they said because they want you to remember the exercise and your symptoms. 

In the vid of the Kalitta Learjet, where they lose pressure at a pretty high altitude, the pilot stays conscious and just functional enough to eventually get them out of it with some help.   The co-pilot was AWOL until they got to lower altitude and then came back pretty strong.    It's an interesting view into differences in different people's susceptibility.   The big lesson I got out of the PROTE exercise was how varied it is for different people.   17k might be very low risk for some people, and much higher for others.
 

 

It’s very odd, hypoxia. I have seen it take out very fit people in the high country. I’ve never done a chamber ride but have done intense hiking at DA’s well above 14k. I don’t feel mentally impaired doing strenuous exercise at altitude but I certainly sound different in videos that I have taken narrating the surrounding landscape.

[Hank]

18 hours ago, Shadrach said:

It’s very odd, hypoxia. I have seen it take out very fit people in the high country. I’ve never done a chamber ride but have done intense hiking at DA’s well above 14k. I don’t feel mentally impaired doing strenuous exercise at altitude but I certainly sound different in videos that I have taken narrating the surrounding landscape.

I didn't feel mentally impaired in the PROTE chamber, but I also knew what was going on. Then they told me to put my mask back on. 

Next time you're up, try doing some simple math, like multiply two-digit numbers or find the outbound leg for an approach whose inbound leg doesn't end in 0 or 5 (i.e., inbound leg is 253°, what's the outbound leg?). Write it down, even record yourself doing the problems and compare the video to how you do the same questions at home afterwards. 

[Pinecone]

19 hours ago, haymak3r said:

I would absolutely love to give this a try sometime.

Info on actual chamber ride, but you have to travel to OKC.   Airman Education Programs | Federal Aviation Administration (faa.gov)

For the traveling setup, use this page and search for PROTE - Activities, Courses, Seminars & Webinars - Seminars & Webinars - FAA - FAASTeam - FAASafety.gov

 

[Vance Harral]

1 hour ago, Hank said:

I didn't feel mentally impaired in the PROTE chamber

For those who don't know, the PROTE setup is not a "chamber" in the sense you might think of.  It's simply a "tent", into which abundant quantities of nitrogen are injected, to reduce the available oxygen.  There's no question this reduces your O2 saturation - you can see it on an oximeter.  As such, you can experience symptoms of hypoxia, and that has value.

That said, whether or not nitrogen dilution at ground-level pressure produces exactly the same symptoms as reduced partial pressure at altitude is debated.  For example, my wife is a professional research scientist.  Her and her colleagues work experiments in an actual altitude chamber a few times a year, as part of their research on pulmonary hypertension, and thus have accumulated dozens of experiences over the years.  Occasionally they are asked to assist with experiments involving a nitrogen dilution tent like the PROTE chamber.  They all swear that the experience and the symptoms in the tent are not the same as in the chamber.

The fact that the people in question are scientists doesn't make this any more "data" than "anecdote".  It's not a double-blind study, and I'm sure there is some group reinforcement of beliefs in casual conversations.  But it stands to reason that in addition to hypoxia, lowering of pressure can have other effects on sinuses, bowels, etc.; all of which may or may not contribute to feelings of unwellness or euphoria.

I've done the PROTE chamber thing, but conversations with my wife have made me curious enough to want to get an actual altitude chamber ride and compare the experiences.  She has yet to sneak me into one of her experiments, though.

[EricJ]

48 minutes ago, Vance Harral said:

For those who don't know, the PROTE setup is not a "chamber" in the sense you might think of.  It's simply a "tent", into which abundant quantities of nitrogen are injected, to reduce the available oxygen.  There's no question this reduces your O2 saturation - you can see it on an oximeter.  As such, you can experience symptoms of hypoxia, and that has value.

That said, whether or not nitrogen dilution at ground-level pressure produces exactly the same symptoms as reduced partial pressure at altitude is debated.  For example, my wife is a professional research scientist.  Her and her colleagues work experiments in an actual altitude chamber a few times a year, as part of their research on pulmonary hypertension, and thus have accumulated dozens of experiences over the years.  Occasionally they are asked to assist with experiments involving a nitrogen dilution tent like the PROTE chamber.  They all swear that the experience and the symptoms in the tent are not the same as in the chamber.

The fact that the people in question are scientists doesn't make this any more "data" than "anecdote".  It's not a double-blind study, and I'm sure there is some group reinforcement of beliefs in casual conversations.  But it stands to reason that in addition to hypoxia, lowering of pressure can have other effects on sinuses, bowels, etc.; all of which may or may not contribute to feelings of unwellness or euphoria.

I've done the PROTE chamber thing, but conversations with my wife have made me curious enough to want to get an actual altitude chamber ride and compare the experiences.  She has yet to sneak me into one of her experiments, though.

Interesting input.    I did find my personal hypoxia symptoms to be the same in the PROTE exercise as I get at altitude, so it seemed to match well for me.   That said, it's not unreasonable to expect that some people may have differences.

[GeeBee]

I'll say one thing about flying VFR at 17,500. It is like doing a straight in at an uncontrolled airport. Yes it is legal. Yes it can work out but it can be terribly selfish. Why? Another aircraft can be at FL180. At FL180 the TCAS computer software is looking in "Class A" mode which means it sees anything less than 1000' creates an RA. Now you would say, "Great, they will avoid me" except just about airline has an SMS program which requires the PIC to write up any RA's. So rather than go home, that poor sob is going to be writing up a useless RA. Equally so, should the RA cause a maneuver other aircraft may be affected. If I want to fly at 17 I go full IFR. I never use 17,500.

[ArtVandelay]

I'll say one thing about flying VFR at 17,500. It is like doing a straight in at an uncontrolled airport. Yes it is legal. Yes it can work out but it can be terribly selfish. Why? Another aircraft can be at FL180. At FL180 the TCAS computer software is looking in "Class A" mode which means it sees anything less than 1000' creates an RA. Now you would say, "Great, they will avoid me" except just about airline has an SMS program which requires the PIC to write up any RA's. So rather than go home, that poor sob is going to be writing up a useless RA. Equally so, should the RA cause a maneuver other aircraft may be affected. If I want to fly at 17 I go full IFR. I never use 17,500.

I’ve never heard of anyone cruising at FL180 or even close to it.

[GeeBee]

12 minutes ago, ArtVandelay said:

I’ve never heard of anyone cruising at FL180 or even close to it.

Ever fly a turbo-prop?  Or fly ATL to AGS?

[Ragsf15e]

3 hours ago, GeeBee said:

I'll say one thing about flying VFR at 17,500. It is like doing a straight in at an uncontrolled airport. Yes it is legal. Yes it can work out but it can be terribly selfish. Why? Another aircraft can be at FL180. At FL180 the TCAS computer software is looking in "Class A" mode which means it sees anything less than 1000' creates an RA. Now you would say, "Great, they will avoid me" except just about airline has an SMS program which requires the PIC to write up any RA's. So rather than go home, that poor sob is going to be writing up a useless RA. Equally so, should the RA cause a maneuver other aircraft may be affected. If I want to fly at 17 I go full IFR. I never use 17,500.

If you’re at 17,500’, you’re required to have a transponder (and adsb), so im thinking that atc is going to deconflict ifr traffic or at least tell them about you even if you don’t use flight following.  Maybe things are different on the east coast?

[jaylw314]

On 2/13/2024 at 11:44 AM, haymak3r said:

I was trying. it was not a very small change in just a slight rotation of the control. Not like down lower. I definitely want to try this again, and this time file a plan to get in to the flight levels. This was a just for fun experiment, so didn't bother. It was a good learning opportunity though.

It does sound like there's something wonky.  The low EGT's suggests those cylinders aren't firing all the time or firing poorly.  I recall getting up to 16.5k', and didn't have any trouble setting mixture or low EGT's.  That being said, I was running at 2700 RPM and shooting for best power (mostly just by listening to the motor).

2 hours ago, GeeBee said:

I'll say one thing about flying VFR at 17,500. It is like doing a straight in at an uncontrolled airport. Yes it is legal. Yes it can work out but it can be terribly selfish. Why? Another aircraft can be at FL180. At FL180 the TCAS computer software is looking in "Class A" mode which means it sees anything less than 1000' creates an RA. Now you would say, "Great, they will avoid me" except just about airline has an SMS program which requires the PIC to write up any RA's. So rather than go home, that poor sob is going to be writing up a useless RA. Equally so, should the RA cause a maneuver other aircraft may be affected. If I want to fly at 17 I go full IFR. I never use 17,500.

I was putzing around at 15.5k' once testing my O2 and checking speeds, when I heard approach call me out to an airliner climbing out of PDX.  The pilot sounded surprised and a little flummoxed when he called visual on me, so I wonder if there's a tendency to relax above 10k' MSL thinking 'phew, at least I don't have to worry about those single-engine maniacs anymore!'

[GeeBee]

30 minutes ago, Ragsf15e said:

If you’re at 17,500’, you’re required to have a transponder (and adsb), so im thinking that atc is going to deconflict ifr traffic or at least tell them about you even if you don’t use flight following.  Maybe things are different on the east coast?

Hopefully they will de-conflict but in busy airspace and descending on a published arrival they might just call the traffic to you. I had this problem several times, one going into ATL at FL180, another in SLC and yet another near TUS. In the case of TUS it was a 500' separation from a Bellanca in class D at night and in sight,  but I got nailed with an RA. Before I could go to bed......Paperwork!

[GeeBee]

43 minutes ago, jaylw314 said:

I was putzing around at 15.5k' once testing my O2 and checking speeds, when I heard approach call me out to an airliner climbing out of PDX.  The pilot sounded surprised and a little flummoxed when he called visual on me, so I wonder if there's a tendency to relax above 10k' MSL thinking 'phew, at least I don't have to worry about those single-engine maniacs anymore!'

Ya think!

[M20F]

17 hours ago, ArtVandelay said:

I’ve never heard of anyone cruising at FL180 or even close to it.

I was at FL250 and ATC told Delta to look for a Mooney passing 2K above them.  They were confused a bit. 

[EricJ]

1 hour ago, M20F said:

I was at FL250 and ATC told Delta to look for a Mooney passing 2K above them.  They were confused a bit. 

lol...that's awesome.

 

[A64Pilot]

On 2/13/2024 at 11:12 AM, LANCECASPER said:

The corn must have been tall that year 

I was doing engine testing to validate a ram air recovery inlet, Pratt came down and instrumented the airplane, it was an Experimental aircraft meant to be armed to primarily drop laser guided bombs from high altitude, but also to be a poor man’s Reaper drone.

I also did our standard crop duster based on the owner of the factory, stupid exercise, waste of time, but this pic was the standard crop duster. I have no idea how high it could have gone, way higher than FL250 certainly but my mask was limited to FL 250 and that was high enough for the data we needed. I’m guessing the one with the Pitot inlet could have gone at least 10,000 ft higher, but I suspect much higher, who knows? It was at light weight with no loads.

Silly as this may sound but I was uncomfortable up there in a Crop Duster.

 

 

[A64Pilot]

Best story I read was the time to altitude record for a helicopter that the Army flew in I guess it was the 60’s in a Sikorsky Skycrane. The record was terminated when the air got thin enough that one of its main rotor blades stalled and fell out of track, causing I’m sure one heck of a vibration, so they started down and ATC called some Airliner and told them their traffic was an Army helicopter descending out of whatever flight level they had attained.

It was apparently over 36,000 when the blade stalled and 1971, the record for some reason is at a lower altitude

https://www.smithsonianmag.com/air-space-magazine/what-helicopter-climbs-fastest-180964354/

The AH-64A at its original mission gross weight of 17,500 lbs would climb at a sustained 5,000 ft per min to at least the first 12,000 ft or so.

Later its gross weight was raised to 21,000 lbs and I don’t remember trying a max performance climb at that gross weight.

The latest model of Chinook can carry significantly more weight than the CH-54 (crane) could and I imagine maybe it could go even higher?

[CCAS]

On 2/12/2024 at 10:39 AM, haymak3r said:

Was I doing something wrong? Just normal limitation of literally being at half atmosphere? Due to old age? lol. Plane, not me of course hehe.

Only pic I took inside:

Until recently I had my 1989 NA M20J based in Colorado Springs and flew back and forth over the Rockies often at 16K/17K (IFR) and 16.5K/17.5K (VFR). Other than climb rates slowly decaying once above 10K' or so, reaching those altitudes isn't too challenging as long as you're patient. Once at crusing altitude, my engine doesn't like LOP operations so I run ROP Economy Cruise (25 deg F ROP) and that's my baseline for power and performance estimates.  I'm certainly not an expert (I'm not an A&P, nor a test pilot, and I've only got about 350 hours of IO-360 Mooney time) but after taking a look at some of your indications I had a few observations and comments.  Apologies in advance if any of the following comes across as obvious,  unnecessary or unhelpful. 

- Outside air temperature: -18 degrees C is close to standard day at that altitude (I believe rough estimate for standard temp would be -20 deg C) so nothing to indicate that non-standard temperatures were robbing you of performance.     

- Airspeed: As you pointed out, it seems low to True out at 148 MPH (approx 130 KTAS) at that altitude in your J.  I could generally count on economy cruise at 138-142 KTAS at similar altitudes with similar gross weight. At those altitudes any mountain wave turbulence, rotor currents or other up/down drafts will spoil a consistent TAS (sometimes for the better but often for the worse).  In any case, airpeed is directly related to the power being delivered by the engine.  

- Power:  You're at 47% power with 15" MP and 2420 RPM. My POH Speed/Power/Altitude chart (max GW) doesn't display direct data above 14K' so I have to extrapolate a bit to estimate what TAS I'd expect for a 47% power condition at higher altitudes....when I do, I come up with a TAS of about 128 KTAS at 16K' and about 129 KTAS at 18K'.  I'd say your airplane is giving you the speed it should for the power it's producing. FYI, I typically plan for 55% power (economy cruise) at 16.5K' using approx 17" MP/2700 RPM. But at 17.5K' I may only be capable of 50% max power (approx 16" MP/2700 RPM).

- Fuel Flow:  You're indicator shows 9.0 gph at 47% power. That seems rich from what I'm used to. For 50% economy cruise at 17.5K I'd normally see about 8.0 gph; and the few trips where I pulled the prop back to 2400 or 2500 RPM I'd see somewhere around 7.5 gph at approx 45% power (economy cruise).   

- Oil Temp: You're showing 192 deg which I'd say is quite good.  I strive to keep mine below 200 deg but on some days, especially in higher-than-standard OAT conditions at that altitude, I've seen oil temp increase to 210-220 deg when I'm at 2600/2700 RPM.  

- EGT/CHT spread: Without seeing each of your cylinder CHT/EGT values it's tough to know if that spread you have displayed is normal or not. I've got a JPI 730 engine monitor and my values have very little spread across each cylinder.  Your one displayed digital CHT (379 deg) seem reasonable but at your power setting I would have expected it to be a bit cooler (maybe 325-350 or so).  Your EGT of 1191 deg seems cooler than I would have expected.  

- Throttle setting: I don't think you mentioned where you had your throttle.  When I'm on a cross country flight, my throttle stays wide open from take off, through climb, and constantly during cruise....especially at higher altitudes. The first time I ease it back is when I'm managing airspeed and CHT temperatures during descent.  

- Mixture: You said you were having difficulties leaning at that altitude but I don't have any insight here.  My technique during a high altitude climb is to coursely lean passing 10K' to approx 10 gpm ff, then again passing 14K' I lean to 9.5 gpm and then after a couple minutes settled in at final cruise altitude I'll use my JPI to fine tune my mixture to achieve 25 deg ROP.    

- Cowl flaps: I'm assuming your cowl flaps are closed and aligned flush with the cowling.   

Based on your engine display and aircraft performance data in the photo, I'd agree with you that you're not making max power at that altitude. Two possible causes could be either an engine issue (as others in this thread hinted at) or pilot power managment technique (throttle, prop and mixture settings). First thing I'd confirm is proper pilot power managment at that altitude (my technique is wide-open throttle, prop at either 2600 RPM or 2700 RPM and mixture leaned to 25 deg ROP). If I were sure I had those three controls set accordingly and I still wasn't getting the power I expected, I'd schedule some time with an A&P to investigate engine performance.