How hot is too hot to fly?

Pi1otguy

Pi1otguy

Pattern Altitude
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Fox McCloud
On the whiteboard at the flight school in working on my BFR it says "No flights dispatched over 99°". I've never seen this when I used to fly in the 2000's
Is this an engine overheating concern or a density altitude concern? Is this common these days? The field elevation is ~800 but the runway is 5000'. I've flown there on hot days a long time ago and it didn't seem dangerous back then. Yes, a 3500 density alt is possible, but there are worse places out there.
 
Likely a culmination of a few different factors. Engine overheating can certainly be an issue with students lolligagging through run-up and ground ops. DA is also a factor; even though it may not be hazardous when executed properly, it's still a consideration. Not to mention the fact that two people sitting in a sun-baked greenhouse for an hour or two can be miserable as the temps climb.
 
As @drummer4468 said, there could be different reasons. I'd ask the flight school its reason for the policy, not us.

One of the flight schools in Denver had a similar policy. 90° for airplanes 180 HP or less; 95° for over 180 HP. In their case it was about density altitude climb performance and the lowest common denominator pilot's* performance in those conditions.

(*the lowest common denominator pilot is often the reason for FBO rental and training limitations)
 
Honestly that’s not as bad as it sounds. I really wouldn’t want to be flying a light aircraft in 99f+ weather…
 
Over the years I rarely flew my Cherokee in 90°+ heat. Just too hot for a practice run. But XC at higher altitude? I'm OK with that, especially in my Mooney.
 
Flying an RV-8 in Florida, my limit is 100 degree heat index. The sun beating through that bubble canopy coupled with the humidity makes it not fun before long.
 
midlifeflyer said:
As @drummer4468 said, there could be different reasons. I'd ask the flight school its reason for the policy, not us.

)
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This. Depends on altitude (DA) and latitude too I would think. I mean, I’ve lived in a place where highs were over 100 every day for two, three weeks straight. That wouldn’t stop me from taking off for a cross country but maybe I wouldn’t have a lesson doing T&Gs in the hottest part of the day. But if you aren’t used to regularly dealing with ultra hot days, I can see such a policy. But then if such days are rare, why make a point of it? Agree with you, ask them what they’re thinking. Maybe they just don’t like people sweating on the upholstery. Maybe they had a case of heat stroke and the lawyer told them to post that.
 
Pi1otguy said:
Yes, a 3500 density alt is possible, but there are worse places out there.
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Yes, there are worst places. I have departed Phoenix several times when the temp is over 109f. Really slow climb to keep the engine temps out of the yellow range, even in a twin.

Here at home the DA never gets as low as 3500 except a few times during winter... :lol: Field elevation approximately 6500.
 
Don't some of the composite aircraft have some sort of limitation on this, or am I making that up?
 
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Challenged said:
Don't some of the composite aircraft have some sort of limitation on this, or an I making that up?
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DA20s have a little turkey thermometer thing...
 
Timbeck2 said:
We went over 108 days straight this year which almost doubled the record.
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Wow. Where we were was very dry. The heat didn’t seem to bother me much. But back East it could be 85 and high humidity I’d be dying.
 
Rushie said:
Wow. Where we were was very dry. The heat didn’t seem to bother me much.
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Yes, Tucson and Phoenix is very hot, but it is a dry heat. Not to worry though, when you burst into flames because of the heat they will be dry flames...:lol::lol:
 
Zeldman said:
Yes, Tucson and Phoenix is very hot, but it is a dry heat. Not to worry though, when you burst into flames because of the heat they will be dry flames...:lol::lol:
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When I was a kid growing up in Phoenix, people would say that all the time and I’d be like “STFU, it’s freakin’ hot!”

Then I spent a summer in OKC with temps like 96F with 98% humidity…..and then I understood what they meant.

But, by far the worst I’ve ever personally seen was Kuwait. Phoenix temps with Gulf of Mexico humidity. Hell on earth.
 
Saw this in an FBO flight school office in the Pacific Northwest earlier this summer ...

CB8AB512-3A75-4A7E-8F29-443EE05FB21D.jpeg

A few years ago when we we had multiple days over 120 deg F here in Phoenix, the local news reported that some flights were canceled because it was too hot for the airliners to fly. Apparently some Part 121 types are temperature limited for takeoff, some to ISA+30 deg C, some to ISA+35 deg C. I'm guessing brake performance might have something to do with it.
 
Zeldman said:
Yes, Tucson and Phoenix is very hot, but it is a dry heat. Not to worry though, when you burst into flames because of the heat they will be dry flames...:lol::lol:
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Head up to MN in the wintertime when it’s -40 outside…it’s a dry cold, so it doesn’t feel nearly as bad. :D
 
Pilawt said:
A few years ago when we we had multiple days over 120 deg F here in Phoenix, the local news reported that some flights were canceled because it was too hot for the airliners to fly. Apparently some Part 121 types are temperature limited for takeoff, some to ISA+30 deg C, some to ISA+35 deg C. I'm guessing brake performance might have something to do with it.
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When we had some 120 days back in the 90s at PHX, the issue was the performance charts for several airlines didn't go that high.
 
MauleSkinner said:
Head up to MN in the wintertime when it’s -40 outside…it’s a dry cold, so it doesn’t feel nearly as bad. :D
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I spent a winter in Fairbanks once. I saw temps in the -60 range, no wind. Yes, It was actually cold enough for me, thank you....

One winter in Kotz we had almost record setting warmth for a week or so right before Christmas. I called a friend of mine that works in Alaska in the summer and wintered around Minneapolis. They were getting -40 temps so I called him and told him to come back to Alaska were it is warmer...:lol::lol:
 
I can't say I've seen that in the MN and IA airports I've flown to. I've flown multiple times when temps were over 95F. Doing touch-n-goes. Absolutely miserable and do not recommend. :p I think the highest DA I've flown at was around 4400'. The climb rate was definitely worse than usual! My CFI had me climb out at a shallower angle to allow for more airflow through the engine, but that was it. Our limiting factor was negative temps. If it got below I think it was -15F, the FBO wouldn't rent the plane because of how easily the plastic broke at temps lower than that and how hard it was on the plane to start up. Or maybe they just didn't want to have to go out in the cold if something went wrong with the plane! ;)
 
Zeldman said:
I spent a winter in Fairbanks once. I saw temps in the -60 range, no wind. Yes, It was actually cold enough for me, thank you....

One winter in Kotz we had almost record setting warmth for a week or so right before Christmas. I called a friend of mine that works in Alaska in the summer and wintered around Minneapolis. They were getting -40 temps so I called him and told him to come back to Alaska were it is warmer...:lol::lol:
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Christmas of ‘83 it was -30 with -60 wind chills in southwest MN…we headed up to Yakutat where it was 35 above. ;)
 
Got around to asking the flight school about the no flights above 99° thing. They say it's bad for the avionics.
 
Fearless Tower said:
But, by far the worst I’ve ever personally seen was Kuwait. Phoenix temps with Gulf of Mexico humidity. Hell on earth.
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I could understand temperature restrictions based on Heat related injuries.

One unfortunate member of my former unit was working in a helicopter in the hell that is Kuwait and lost consciousness and did not receive medical attention until it was too late. He suffered brain damage and was eventually medically retired, but was still alive.

The Army treats heat injuries as a threat and adjusts exposure to mitigate the risk of injury. That doesn't mean ops are canceled due to heat, but controls are put in place to "make the best of a bad situation."
 
It's only been a few weeks ago that I departed from an airport.. not sure the actual OAT that day but probably in the 90s. I seriously considered aborting because while taxiing out sweat was dripping into my eyes and making it hard to see. A little altitude and airflow through the vents took care of it.

I'm fairly sure the airplane didn't notice.
 
Pilawt said:
Saw this in an FBO flight school office in the Pacific Northwest earlier this summer ...

View attachment 100236

A few years ago when we we had multiple days over 120 deg F here in Phoenix, the local news reported that some flights were canceled because it was too hot for the airliners to fly. Apparently some Part 121 types are temperature limited for takeoff, some to ISA+30 deg C, some to ISA+35 deg C. I'm guessing brake performance might have something to do with it.
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Where was this? Even in western Washington those temperature limits are just nuts.
 
cowman said:
It's only been a few weeks ago that I departed from an airport.. not sure the actual OAT that day but probably in the 90s. I seriously considered aborting because while taxiing out sweat was dripping into my eyes and making it hard to see. A little altitude and airflow through the vents took care of it.
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My little experimental with the bubble canopy gets pretty hot with the canopy closed. I have flown with temps in the mid to upper 90's. In the southeast it's the humidity that wears you out until you get up a few thousand feet.

The good news is my engine runs cool even when it gets hot outside so I can climb up and into some cooler air soon enough. The problem is when I have to sit while waiting for other folks to get gone or get out of the way.
 
Pi1otguy said:
On the whiteboard at the flight school in working on my BFR it says "No flights dispatched over 99°". I've never seen this when I used to fly in the 2000's
Is this an engine overheating concern or a density altitude concern? Is this common these days? The field elevation is ~800 but the runway is 5000'. I've flown there on hot days a long time ago and it didn't seem dangerous back then. Yes, a 3500 density alt is possible, but there are worse places out there.
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The flight school I attended had a 95°f limit.I have flown in warmer temps in my own plane.
 
I would take a dry 115 degrees all day over 90% humidity 90 degrees. I went to Vegas for my birthday a few years ago in July and it was way more comfortable there than at home in New York.
 
I’ve never seen an upper limit at an FBO or club. But ask me about the time I took off from ZPH in a 172 and my iPad (EFB) overheated before the wheels left the ground.
 
I have never considered it too hot to fly, but it certainly is always comfortable. A couple of months ago I had a 421 on the ramp all day, I was sweating so bad that I wished I had a towel so I could wipe my face so I could see better. AC barely made a difference and my flight was only 61 miles so I couldn't get enough altitude to reach cooler air.
 
ateamer said:
Flying an RV-8 in Florida, my limit is 100 degree heat index. The sun beating through that bubble canopy coupled with the humidity makes it not fun before long.
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The largest operator of my aircraft type has a 90 degree rule, so I follow that.
The Sportcruiser canopy is already an oven, add some bumpy thermals and it becomes a rough day pretty quickly. Besides engine temps, we try to baby the voltage regulator. I am told there may be a solution for that soon.
 
Pilawt said:
VUO. Essentially at sea level, 3275-foot-long runway, but there are some obstructions.
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Interesting. I'm not aware of any temperature limits for the club's airplanes, but then 17/35 at KOLM is about 5500 feet long and the field elevation is only about 206 feet, so take-off performance isn't really an issue for us.
 
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