Heat Wave

Jaybird180

Jaybird180

Final Approach
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Jaybird180
As I'm thinking of a quick 1hr flight and return, I would like the weather experts to explain what is causing the heat wave were having in the DC area (or the mechanics behind what makes a heat wave).

Also anyone - What is the highest DA above PA you've operated from?
 
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Jaybird180 said:
Also anyone - What is the highest DA above PA you've operated from?
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I flew out of Front Royal, VA (FRR) yesterday. Density altitude was over 3,300 feet, my record so far. Field elevation is 709 feet. The glider I was flying didn't seem to mind :)
OTOH, the PA-25 Pawnee tow plane's climb rate was relatively anemic. The 3,000 ft runway was enough, though, and we were still safely above the trees at the departure end.
 
La Nina.

And I flew out of KFKL a few times with DA in the 4K range (field elevation 1542).
 
According my aux book, I once flew (as a pre-solo student) from KABQ to GNT and back when DA was 8700. ABQ elevation is 5300. However, my official logbook says it was on Novermber 3. On reflection I think it cannot be that hot in Albuquerque in November, I must've miscalculated.
 
It'll be interesting to hear some of the DA's that the Rocky Mountain boys have flown in. What do you say Cary?

Doc
 
I flew home from El Paso lately at 11,500 ft with a DA of about 14K or so -

I started out at 9,500 but the thermals and bumps were still too bad so I climbed and it was still sorta bumpy! That's why glider guys like it so much out here I spose :yesnod:
 
1200AGL said:
I flew out of Front Royal, VA (FRR) yesterday. Density altitude was over 3,300 feet, my record so far. Field elevation is 709 feet. The glider I was flying didn't seem to mind :)
OTOH, the PA-25 Pawnee tow plane's climb rate was relatively anemic. The 3,000 ft runway was enough, though, and we were still safely above the trees at the departure end.
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I was tow pilot today, airfield at 2833 MSL, DA was over 6000.
No problems climbing out, especially when you find the 8knt thermals to use on tow. We have no trees, but that is why we replaced our Scout with a 250HP Pawnee. High DA days with a Grob 103 at max GW is no fun.

One of our instructors was also flying the CAP L-23 today behind the CAP C-182 tow, not fun. Makes one really appreciate that Pawnee.
 
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BillTIZ said:
I was tow pilot today, airfield at 2833 MSL, DA was over 6000.
No problems climbing out, especially when you find the 8knt thermals to use on tow. We have no trees, but that is why we replaced our Scout with a 250HP Pawnee. High DA days with a Grob 103 at max GW is no fun.

One of our instructors was also flying the CAP L-23 today behind the CAP C-182 tow, not fun. Makes one really appreciate that Pawnee.
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"Anemic" in my last post was a poor choice of words. I'm spoiled :)

Earlier this season we held an 'away day' at a nearby 2,600 ft. grass strip, towing with an Aviat Husky. When the DA hit 2,500 ft with a slight tailwind on takeoff, we had to stop towing the Grob 103 with two aboard for safety.
 
Yesterday we took off from KBJC in the Navajo. DA was something around 7500-8000. We then went up to 11k for cruise, DA in the 14-15k range. Put those turbos to work. :)
 
dunno what the DA was, but probably when I was at Lake Havasu and the temp was 122F.

BCE AWOS was reporting 11,400 (7560MSL) the next day when I was there.
 
1200AGL said:
"Anemic" in my last post was a poor choice of words. I'm spoiled :)

Earlier this season we held an 'away day' at a nearby 2,600 ft. grass strip, towing with an Aviat Husky. When the DA hit 2,500 ft with a slight tailwind on takeoff, we had to stop towing the Grob 103 with two aboard for safety.
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Is there a reason you could not tow from the other end? Turn that tailwind into a proper headwind. Some glass birds don't like tailwind takeoffs, not enough aileron control early in the run. And the Pawnee hates landing in tailwinds.

Our runway is 3500ft paved with at least 600ft of gravel or more at each end and any obstructions are at least 1000 ft or more away.
 
Jaybird180 said:
Also anyone - What is the highest DA above PA you've operated from?
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650 MSL but DA around 6400. Hot, humid, low pressure system, midday sun.

Texas summers can suck.

Luckily, I was flying solo in a DA40 with half tanks, so there was plenty of climb.
 
KAPA DA is currently 8700'. Temp 31, Altimeter 30.16, Field elevation 5885
 
Flew GAI-LNS and back last night from about 9pm to midnight. The 172's climb rate was less than spectacular. DA was 2000 and change, IIRC...
 
In contrast, yesterday (24 July) was the first time this year I could fly my open-cockpit airplane without having to wear a jacket.

Got up to 83 yesterday!

Ron Wanttaja
 
yesterday was the 10th day in a row over 100 and our 30th day this year. i think i read it was somewhere around 107. Today we had a break, it is only 98
 
xaminmo said:
650 MSL but DA around 6400. Hot, humid, low pressure system, midday sun.

Texas summers can suck.

Luckily, I was flying solo in a DA40 with half tanks, so there was plenty of climb.
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What were those numbers? Even at an elevation of 650MSL, altimeter at 29.00 and a temp of 125F I only compute the DA at 5902.
 
BillTIZ said:
What were those numbers? Even at an elevation of 650MSL, altimeter at 29.00 and a temp of 125F I only compute the DA at 5902.
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I don't remember, but I could have sworn it was below 29". Was in 2008, so there is a possibility of fuzzy memory at play.
 
xaminmo said:
I don't remember, but I could have sworn it was below 29". Was in 2008, so there is a possibility of fuzzy memory at play.
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I know it gets hot and humid in Texas, need to climb up to cooler air to be comfortable.
 
COFlyBoy said:
KAPA DA is currently 8700'. Temp 31, Altimeter 30.16, Field elevation 5885
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And here I thought this was a discussion about Irving Berlin music.

It's not unusual for us to see DA in the 9000s around 3-5 pm in the summer. APA ground is 5885, FTG ground is 5512.

It's not the ground DA that gets us, it's DA at altitude. Group went to lunch last week at Salida (ANK) which is 7523. The problem for me (180 HP) is a service ceiling of 15.5K and a ridge at 10.5K. Going over at 12.5K DA is 15.8K. It's coming home at 11.5K, altimeter of 30.48 and OAT of 25C. That's DA of 15.1K so I'm not going unless I can ride along with someone with a bigger engine.
 
scottd said:
Not holding back...that's the answer. Not much more to add.
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So what causes pressure zones? Why doesn't barometric pressure equalize all over the planet? Why is the phenomenon localized?
(I have the feeling I just asked a complex question that I won't comprehend the answer at first glance - but let er' rip)
 
Jaybird180 said:
So what causes pressure zones? Why doesn't barometric pressure equalize all over the planet? Why is the phenomenon localized?
(I have the feeling I just asked a complex question that I won't comprehend the answer at first glance - but let er' rip)
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This is one of the reasons I'm not fond of "aviation weather" courses offered at various colleges, or even the FAA's weather document. It really doesn't explain climatology or meteorology. But here's how we described it at the local museum when we had a major exhibit on Weather.

1. The sun causes weather.

Radiation from the sun heats various materials unevenly.

Water warms/cools at a different rate than aluminum or dirt or various crops. It gets hot and the first thing you want to do is find shade, right? Add in the tilt of the earth and remember that in the north it's hot and in the south it's cold. Ever do the experiment in grade school of taking a very hot liquid that you've added food coloring and pour it into a beaker of really cold water and watch the swirls?

Watch the air above a flame - kinda wiggly, right? Now translate that to radiant heat from a hot ground into the air. Welcome to pressure gradients.
 
scottd said:
It's due to that big orange ball in the sky and the fact that we live on a rotating body. Unequal heating, verticial and horizontal distribution of air density from differences in pressure, temperature and moisture are what cause this kind of subtropical ridge pattern (or any pattern on any given day).
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Is that an over-simplified version? I would have thought that it would be cyclical.
 
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Highest DA for takeoff/landing? 12,200 feet at KLXV. Ground roll on takeoff in the 182 was about 2,000 feet, or 3x a normal takeoff roll.

Highest DA for flight? The next day, cruising at 17500 MSL, the G430 showed DA as 18,848 feet.
 
11,300 out of Telluride Colorado, in a Skyhawk.

217733_1679140338851_1247804014_31388521_7908922_n.jpg
 
scottd said:
Very simplified, but the basic elements are contained in that explanation.
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And here I thought it was Mongo eating that pail of baked beans.
There is a Coast Guard Auxiliary class that does a fair job of teaching weather. Of course, being boating oriented, it does not give a lot of info on aviation weather.
If you're interested: AUXWEA
I'd be interested in your course should you get to Boston. I just bought the CD course from Pilot Workshops.
https://sites.google.com/a/cgauxnet.us/universities/program/training/weather
 
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