Cessna 172 Won't Take Off

I am trying to locate the Grand Canyon by flying from the closest airport - KGCN - Grand Canyon National, which is very close to the park. My objective is to try to VFR along the canyon. I can’t climb even at the slowest rate of climb at full throttle. Takes off and climbs fine from my home airport in NJ.

Adjust your mixture. You are at 6,600 ft.


What do you suggest?

Correction, you are at 6,600 ft, not 9,000. As for where the mixture should be, run the engine up on the ground, to about 75% throttle (hold the brakes!), and then lean the engine until revs drop, and then make it a tad richer.

Got It - Have never taken off from any location that is not pretty much at sea level or close to it.

Even at SL you need to lean to 75% due to the faulty FSX mixture simulation.

FSX or MS 2020? I am trying to fly MS 2020. Never flew an MS Sim prior to MS 2020

MSFS and FSX. This bug has been carried over from the old sim.

Since it is all a little buggy, I have auto-mixture turned on to avoid the whole issue. Seems to work ok.

I thought that your bird didn’t want to take off at all! I was about to suggest you just to stay on the ground 0ft, QFE altitude-terrain with your 172 and to enjoy the fields around: elephants, bonobos, gnu, hmar etc (kidding you) :grin: ! …
Yeap as mentioned if the OAT is high especially isa+° and/or if your airfield is located at a high altitude then the air is not that dense so that leaning your mixture and having a long runway for the rolling-take off will help you to get your VR and to rotate in a safe way to V2 and so on in order to make yourself happy and your pax Captain! :wink:

Try the airfield L41, it’s a nice spot!!! (not that far from KGCN) :airplane:

Where is auto-mixture - can’t find it to turn on. Is this a snipe hunt?

lol no it is in the realism settings: Options->Assistance->Aircraft Systems->Automixture

Thank you for the info - Learning this thing is like trying to think in braille. The has been a whole lot of bi$#hing about the lack of documentation. It would have been so much easier for me to learn this sim with any sort of written down stuff.

I am an experienced xp11 flyer and even with loads of documentation I am still learning. I never flew a sim before xp11 and being a VFR, low and slow, sightseer I was intrigued with the prospect of more realistic scenery and still am.


BTW, when I purchased the Premier version of the sim they gave me this dorky name and image that I would really like to chage

What is the nature of the mixture bug? Can you detail it?

I just watched a 30 min tutorial on YouTube of a guy showing how to use mixture using a 172 in FS3020. He didn’t mention anything about bugs and everything seemed to work the way he thought it would…

Thats not just a guy, that’s Squirrel! I think OP can also learn something from that video:

There are quite a few things wrong with the mixture simulation since (at least FSX).
The main problem is that while IRL, as others have mentioned already, you usually don’t lean below 3000ft, you need to do so in MSFS.

Simply run e.g. the 172 engine at 100% throttle and 100% mixture at SL with the parking brake on and note the RPM.

Now pull pull the mixture lever back to ~75% and you will notice that the RPM increases by ~200RPM which is a lot.

IRL you can fly even at 10000ft without leaning the mixture, in FSX/MSFS the engine will die due to the lack of leaning.


I don’t know who Squirrel! is, but does he mention anywhere in the video that you need to lean then engines on e.g. the 152 and 172 much more than IRL and even at SL?

There’s a bug where the fuel flow peaks before reaching full rich. Normally, fuel flow linearly increases as you enrichen the mixture. In MSFS, it increases until about 90% rich, and then it sharply decreases. My suggestion is at sea level, go full throttle and full mixture, and then slowly lower the mixture until the fuel flow gauge peaks. IRL this is not something you’d do - just a workaround to fix the bug.

I am a VFR guy myself so this sim is perfect for my interests. If it weren’t for resources like this forum though, I wouldn’t have been able to navigate the interface.

I am already using auto mixture. When flying the Cessna 172 out of KGCN the rate of climb is painstakingly slow, and have to keep it at a rate of 5 to gain any acceleration at all. Best speed upon level out is barely above stall speed (60). I then took off from KGCN in the in the single engine turbo prop and headed toward the mountains at about 120 after a great climb out. Took a left at the canyon and flew sometimes very low between the walls at about 80 for about 25 minutes. The scenery is quite spectacular!