high density altitude landing...

[dtvonly]

When landing at a high altitude airport (say above 3000 feet), should the mixture be kept the same as it was at cruising altitude?

 

[oregonboy109]

I would consult the POH but I would think yes.

 

[Clark1961]

When landing at a high altitude airport (say above 3000 feet), should the mixture be kept the same as it was at cruising altitude?

On normally aspirated engines the mixture should be set for best power prior to landing at high density altitude.

 

[CharlieTango]

If you take off from the same high density airport that you are going to land at you can note the take-off setting as in '1 finger' and use that.

 

[James331]

Depends on what you're cursing at.


Use your performance charts, more over look at your analyzer, keep CHTs and EGTs at or around target.

 

[MAKG1]

On normally aspirated engines the mixture should be set for best power prior to landing at high density altitude.

Even at low throttle?

Most of us, particularly in high performance aircraft, operate at low throttle during descent and prior to landing.

What you can do is enrich if it gets rough, but otherwise leave it alone. Maybe give it a little twist in prior to landing, but it's very easy to overdo that

If your POH gives guidance, that trumps, but few of them say much.

If the aircraft has a pressure regulator labeled as fuel flow (e.g., 172RG or 177), you can probably use it at low power the same as high. But if it's a real fuel flow gauge, it will be wrong at low throttle and can't be used for that purpose. That is, I can't just set the 182 to 12 GPH like its best power placard says, 'cause that's for takeoff and presumes full throttle and fine prop.

You may be able to set up a low power cruise to use the cruise tables, but I think you'll be off the bottom, depending on model.

 

[Clark1961]

Even at low throttle?

Yes, set mixture for best power at WOT. Set the mixture at pattern altitude so on the downwind is a handy place to do it. It'll idle just fine at that mixture setting. Read Sparky's book or take a high density altitude operations course such as Colorado Pilots Assoc. puts on.

 

[BillTIZ]

When landing at a high altitude airport (say above 3000 feet), should the mixture be kept the same as it was at cruising altitude?

No.
I cruise at 10,000 - 12,000 MSL, DA at cruise is higher than that.
Landing at a 3000 MSL airport, the DA may be about 5,000 adjust the mixture for the altitude.

If I kept the mixture at the 12,000 cruising setting and did a full power go around at the 3000 ft airport I would be way to lean.

 

[pigpenracing]

I love my Pitts Model 12 and J-3 Cub. Either one have a mixture control so I don't have to worry about these things

 

[yakdriver]

I love my Pitts Model 12 and J-3 Cub. Either one have a mixture control so I don't have to worry about these things

The problem with automatic mixture control is you can't clear up a snotty plug on run up on the M14P. I like manual mixture control. Don

 

[denverpilot]

If you've really never had that particular airplane and powerplant up to a high DA airport and have a feel for about where the mixture should be for best power, you can always start your descent a bit early and figure out what best power is at around 2000 AGL or so using ehatever EGT tools you have on board.

Then give the vernier a little half twist in from there and you're probably "close enough" without being too lean for a go-around.

At least on a normally aspirated and non-injected engine this is going to be fine. It's not that critical.

What you'd want to avoid is going full rich. You'd hear the engine blubbing and it'd do nothing but sound worse when you added carb heat (richer mixture). My O-470 runs like crap at DAs of 8000 and above at full rich. It's *really* obvious. Especially with the carb heat on.

 

[Theboys]

I use TIT temp and just get it to 1400. No reason you couldn't do same with EGT.

 

[Cpt_Kirk]

I use TIT temp and just get it to 1400. No reason you couldn't do same with EGT.

Never, ever set a power setting using only the EGT to a predetermined numerical value. That's just asking for trouble.

 

[Ted]

Never, ever set a power setting using only the EGT to a predetermined numerical value. That's just asking for trouble.

I guess those Navajos with millions of hours of flight time operated exactly that way have been asking for trouble.

(BTW I agree it's not optimal, but it is by no means doom and gloom)

 

[Sac Arrow]

I do not enrichen for landing at sea level, much less at high density altitude. Having your engine quit from flooding is a bigger problem than an underpowered or rough running engine from being too lean.

 

[frfly172]

I have a fadec controlled engine.no mixture controll,if your nervous on take off or landing at high density airports use percent of power settings.

 

[MAKG1]

I do not enrichen for landing at sea level, much less at high density altitude. Having your engine quit from flooding is a bigger problem than an underpowered or rough running engine from being too lean.

BTDT, and I thoroughly concur.

It can be tough to feel the roughness with a good CS prop and matched injectors.

If you do need to go around, you can fine tune the mixture after going full throttle, using the best power placard. If the mixture is too rich at the start because you tried to follow max EGT at low throttle, a go-around isn't happening. If it's too lean, a couple of pings of detonation is much easier on the aircraft than landing in the rocks (and it's exceedingly unlikely at a high density altitude).