High density altitude takeoff and landing

[FloridaMan]

I'll be doing some work at some hot and high fields out west this week (6000+/-). How do you guys manage your takeoff and landing configurations at these types of fields?

[Cruiser]

Use the targeted EGT method. On run up, lean the mixture to around 1280 - 1300 EGT for the IO360 or the equivalent of sea level full rich EGT. On landing just leave the mixture alone from cruise and you should be good all the way to the runway or set it to the sea level full rich value above in preparation of a go around.

[Lood]

Agree with the target EGT method - mine is 1250 deg. Also, don't attempt such take off fully loaded or when it's very hot and make sure you have enough runway and no excessive high ground directly in your climb path. BTW, what are you flying?

[RJBrown]

Do not go full rich. My J never sees full rich take off or landing on my home field (APA) 5880' Full rich can cause loss of power and fouled plugs.

[Hank]

Where do you put the mixture for a go-around at altitude? I've never done one, but was startled into thinking about it flying into Rapid City when they were calling DA of 6800'. Seems the ATIS broadcast said something about leaning for maximum performance according to your POH, too. But it made me wonder--as I'm flying in, how do I do that? I know how to do it on the ground before departure.

Departing the next morning, DA was not an issue, and I don't remember how I leaned; probably for max RPM while standing on the brakes.

[omega708]

Use the targeted EGT method. On run up, lean the mixture to around 1280 - 1300 EGT for the IO360 or the equivalent of sea level full rich EGT. On landing just leave the mixture alone from cruise and you should be good all the way to the runway or set it to the sea level full rich value above in preparation of a go around.

Do you lean for 1280 - 1300 at normal run-up RPM or do you go full throttle for this procedure. I assume you also continue to monitor the EGT during climb out to try and maintain the targeted EGT range?

[Hank]

The "Target EGT" method uses EGT in flight, so do the pre-departure leaning at full throttle. Then occasionally lean it back during climb, to maintain your target value.

The target value for your plane may or may not match that of any other plane. To determine your target EGT value, depart close to sea level on a day very close to ISO standard, and observe your EGT on initial climbout. THAT is your target value.

At least this is my understanding of the process. So I guess I answered my own question--when landing with high DA, lean for my target EGT and I'll be go-around-ready if needed.

[Lood]

If you're landing at a high altitude airport in a normally aspirated Mooney, your cruising altitude will not be much higher than the airport itself . So, you won't need a lot richer mixture, if any, to be ready for a go-around. I normally cruise at around FL085/095, 75 deg ROP. This leaves all my EGT's in the 1360 deg region. My home field is at 4000 feet and normally, two turns on the mixture once at circuit altitude puts my EGT's back at around 1300 deg, which is adequate for a go around.

Whenever I descend from FL105 to a low level airport, for instance, I simply reverse the leaning process. I keep an eye on the JPI and just keep the EGT's at around 1350 deg by enriching the mixture as I descend.

[FloridaMan]

I've got a '67F w/ LoPresti cowl, Powerflow exhaust and GAMI injectors. The plane makes good power at altitude, though I almost always have the ram-air open in cruise. The previous owner said he had no trouble with three people in the plane and half tanks at Leadville, but I'm new to high altitude operations. Bruce Jaeger had me do my stalls and recovery at 9000ft to familiarize me with the characteristics at higher DA.

I don't have a calibrated EGT. On my runup here in FL, I lean to where I see a 75 degree increase in the EGT after increasing RPM, but before checking the mags. I've heard it said that you should break out the POH if DA exceeds runway length. I'm looking at landing at Plainview, TX and North Las Vegas.

[jetdriven]

When landing, set the mixture about 2 turns in from the cruise setting, or what approximated peak egt on downwind plus a little extra.

For takeoff the plane performs fine. We departed a few times from Sedona, with a 7500 DA. Taxi with the mixture as lean as possible. Do a normal runup with the mixture set to peak RPM. At takeoff, hold the brakes, richen the mixture about 3 turns from runup, set full throttle, lean to 1250 EGT and go. An alternate method is quickly find peak EGT (just get it close, dont fiddle), and richen 250 degrees. At 6000 DA or more, richen to 80 ROP. That approximates best power. Just watch CHT closely on departure and richen some if any exceed 380.

[mike28w]

I've got a '67F w/ LoPresti cowl, Powerflow exhaust and GAMI injectors. The previous owner said he had no trouble with three people in the plane and half tanks at Leadville, but I'm new to high altitude operations. Bruce Jaeger had me do my stalls and recovery at 9000ft to familiarize me with the characteristics at higher DA.

I used to base my '63 C at an airport of 5,200'. DA would commonly be above 10,000 in the summer. Carried me and the wife and full tanks (48 gals) but no more ! Everything that the POH says about max gross is wrong at that DA !! IMO. When you're playing with high DA, start out way lighter than the POH says. Expect much longer take off runs. Do fly it by the indicated airspeed numbers. If you're careful, I firmly believe that you can fly safely at this DA.

I don't know how much better your plane will perform than mine but I still think you should start conservatively until you know for sure. You don't want to break your plane ( or your neck) ! Mike

PS: It doesn't take a very warm day in Leadville for the DA to be quite impressive ! Temps matter.

[Hank]

But what about when coming in to land with high DA? Surely I don't need to try to find peak EGT in the pattern and richen up 150º or so?

P.S.--my mixture, like prop and throttle, are levers on a quadrant, they don't turn. I already keep MP and EGT near cruise settings during descent. The day I went to KRAP I flew at 8500 msl; KRAP is ~3800 msl, calling DA of 6800'. Where do I put the mixture to land? No injectors, either--just an O-360 that I taxi leaned 50-60% back.

[jetdriven]

Hank, you should be near peak when approaching to land. Just richen it a little from that. It is imprecise. But it doesnt have to be exact, just close enough it wont stumble when going around, or too lean.

[Lood]

I've got a '67F w/ LoPresti cowl, Powerflow exhaust and GAMI injectors. The plane makes good power at altitude, though I almost always have the ram-air open in cruise. The previous owner said he had no trouble with three people in the plane and half tanks at Leadville, but I'm new to high altitude operations. Bruce Jaeger had me do my stalls and recovery at 9000ft to familiarize me with the characteristics at higher DA.

I don't have a calibrated EGT. On my runup here in FL, I lean to where I see a 75 degree increase in the EGT after increasing RPM, but before checking the mags. I've heard it said that you should break out the POH if DA exceeds runway length. I'm looking at landing at Plainview, TX and North Las Vegas.

You'll be fine with the take off and everything. Just expect to see a rather poor ROC when it's hot AND if you're heavy at the same time. My '67F climbed out of Upington here in SA at about 150 - 200 ft/min - fully loaded. Upington is not very high, but it does get extremely hot there in summer.

[Oscar Avalle]

I am currently based at a field that is 4980 feet high. DA often goes through the roof. The performance has taken a hit, longer take off rolls, but you can still fly as long as you follow the POH and check the density altitude. The other day it was hot and DA was about 9800 feet. Very interesting to say the least. Also when you come in for landing your ground speed will be faster at the same indicated airspeed. Thus it is very important that you keep an eye on the IA and don't be too fast. One thing that I installed and that helped me is an Angle of Attack indicator.

[carusoam]

Oscar is there an App that you use to calculate density altitude?

Since you need to know this detail each time...

Best regards,

-a-

[Oscar Avalle]

I use my superclock from Electronics International. It tells me indicated and density altitude.

http://www.aircraftspruce.com/catalog/inpages/ei-instruments-carbtemp10.php

[carusoam]

Thanks Oscar.

-a-

[Stefanovm]

All good information. I lean to about 1200. That is my Mooney's sea level take off indication. I have yet to verify when the temperature is not 10+ degrees above standard for an above sea level DA. Most of the places I have flown in the last three years broadcast the DA. My KLN94 calculates it much easier than my aluminum E6B Flight Computer, but that is after engine start.

Leaning the EGT way worked great at Sierra Vista, AZ in July, 2010, and within 10% of full gross for most of the ten TO&Ls. The DA was over 10K, but 10K+ feet of runway helps the concern factor. It took almost 2.5K of runway to get 50' AGL, but 400' AGL before the 10K end of the runway. I have used the same process with quite a few high DA TO&Ls in my Mooney travels, 50+.I did not learn the formal process until getting my Mooney. As a California high desert flyer in my first three airplanes, I probably used the same process, but just by needing to get the job done rather than knowing it is the a recommended process.

In Sierra Vista, I worked my gust practice to death giving rides to family. Even my sister-in-law went. She has never wanted to go and the turbulence bothered me more than anyone except my 5 year old nephew. Turbulence rarely bothers me. However, landing with it constantly over a few hours is tiring.

My Mooney is the best of the five airplanes that have had owned my wife and I since 1977. They include '69 C150 ('77), 74 C182 ('78), '62 C310 ('81), '78 C152 ('03), '65 M20E ('10), the last planned.

[Stefanovm]

The "Target EGT" method uses EGT in flight, so do the pre-departure leaning at full throttle. Then occasionally lean it back during climb, to maintain your target value.

The target value for your plane may or may not match that of any other plane. To determine your target EGT value, depart close to sea level on a day very close to ISO standard, and observe your EGT on initial climbout. THAT is your target value.

At least this is my understanding of the process. So I guess I answered my own question--when landing with high DA, lean for my target EGT and I'll be go-around-ready if needed.

That is how I do it. Probably less that 10 have been done, mostly missed approaches during simulated approach practice. One was an airplane that did not get off the runaway, so closer to being less planned as the tower commanded it.

[Stefanovm]

Here is more information, a 3,400 DA at an 800 MSL airport, my home one. Calculated from http://wahiduddin.net/calc/calc_da.htm at 07TS, a 2.500 foot grass strip on a summer day. I rarely do this TO when anywhere more than 2,200 lbs.

[Freight Dog]

Oscar is there an App that you use to calculate density altitude?

Since you need to know this detail each time...

Best regards,

-a-

Check out AutoDens on the AppStore... it's free as well.

[carusoam]

The Stefanovm site includes humidity in the calculation. Not as portable as an i version.

WingX also helps with their version.

I'll check out AutoDens.

East coast departures are not that critical, at 125' msl and 3,000' long runway...until it is hot again and fully loaded.

Thanks,

-a-

[FloridaMan]

Well, I made it back and put nearly 30 hours on the tach during the trip and had zero issues with the airplane. I tried to mitigate my risks by having fuel stops at Longview on each trip. If I was gonna get stuck with mx problems, Don Maxwell's home base would be the place to be.

KABQ at night was the most challenging to get the airplane under control and to the runway because of the 9000 feet of altitude I had to lose in just a few miles to get to the airport when approaching from the east. I had to do a 360 out over the city to bleed off altitude. I had that sinking feeling in my stomach in the flare that I'd left my gear up. Fortunately, redundancy in my routine ensured that it didn't happen, I just didn't check across the threshold because my hand was on the throttle because I thought I wasn't at idle. The combination of DA and the slight quartering tailwind I had on landing on the assigned runway gave me a higher ground speed than I was used to seeing. Normally I reach down and lift and twist on my johnson right as I cross the numbers, but my right hand was still messing with the throttle. The redundancy is that I will never allow the gear warning to go off without taking immediate action, either by dropping the gear, pressing on the warning switch inside the gear retention, or adding power.

The next day, crossing New Mexico, there was a moderate turbulence airmet. I caught about 10-15 seconds of SEVERE clear air turbulence and then it was gone. If you've never experienced this, it will get your attention and it was absolutely terrifying.

[N601RX]

Oscar is there an App that you use to calculate density altitude?

Since you need to know this detail each time...

Best regards,

-a-

I installed the Davtron 655. It shows OAT, density an pressure altitude. It hooks into the encoder, so the pressure altitude is the same as the transponder sees.