I live in Denver, KAPA. I am so grateful I learned to fly here. Density Altitude is always a part of my flying, so is the 70/50 rule. Sometimes you can’t even consider flying during midday. Love your videos!
I've flown in a 737 dozens of times. I'm used to them getting airborne with plenty of room to spare, off of 6000ft runways. It was a real eye opener watching most of the almost 11,000ft runway zip by taking off from Sana'a, Yemen in the middle of summer...and we were really scooting across the ground by the time we got up. The airport is at 7200ft ASL and in the summer, density altitude is often over 10,000ft. If you fly where there are cold winters and hot summers...the difference in performance of a 172 or Cherokee is very dramatic.
In the winter my 172M climbs 1,000FPM at full fuel and two pilots at 4606MSL. In the summer? We're lucky to see 400FPM with that load. I usually fly at minimum fuel during the summer. Absolute minimum 30 minutes to try to squeeze 800FPM initial climb out of it. We're in mountainous terrain so we need as much climb as we can get.
That happens a lot in Buenos Aires, Argentina. Summer temps are usually above 34/35ºC and sometimes would exceed 40 on some days, variating performance a lot.
Had a Piper Warrior loaded up to just under 2400 pounds. It was 30 ish degrees, pressure altitude on the ground was probably around 700 feet. We were doing a WHOPPING 300 fpm at Vy climbing through 2500!
Hi Jason, started my PPL journey back in May and stumbled across your videos (and ground school) while studying. Here on the east coast we’ve had exceptionally hot temperatures so this video comes at a perfect time to help visualize what’s going on in the PA28 I’m flying. Thanks!
I flew closer to max gross than I ever had before over the weekend. Not a terrible density altitude, but I certainly experienced the perceived sluggishness with the extra weight. Just held rotation attitude and let her fly when she was ready
Currently in training at KFLY and in the summer it hits 9,500 Density by 10am and will often get above 10. Combine that with consistent 15kt (or higher) winds and things can get very interesting in a c172.
Awesome video, I recently experienced a sketchy take off at a short field at max gross weight that made me start paying more attention to the density altitude. Luckily I cleared the trees at the end of the runway, but the pucker factor has very high !
As your friend was calling off runway remaining his voice changed.. Fly a (non-turbo) Arrow IV out here in AZ, DA is a fact of life. Notch 'o flaps for takeoff can be almost mandatory.
I experienced a few high density altitude takeoffs in my Arrow 180, at maximum gross weight, during Oshkosh. It’s amazing how much they don’t want to climb when they’re heavy!
Jason, super informative video as always. So sorry I missed your talk at the NAFI booth! I flew in with my son and had to leave early to beat bad weather home in KY. Maybe next year!
Jason it was great meeting with you after your NAFI presentation Friday morning. Thanks for your insights and have a great life of instructing. Blue skies!
the other thing I noticed in a high DA is how long the turbo takes to spool, you could eat a lot of runway just waiting to reach max power. I hold the brakes until the turbo lights off, it took 10 seconds for me to reach 36.5" of manifold pres. last time I took off from flagstaff AZ
Currently learning to fly the wonderful 172XP in an average of 7000-8000’DA. It’s been an absolute joy to learn this style of flying… except that one time we took up a 100hp 150 we were thinking about buying… that time wasn’t an absolute joy lol
i bet compared to taking off at 8000 feet at home that the 210 felt like a rocket ship taking off at 800 feet :D i havent had that "luxury" yet as florida, everywhere is < 300ft above sea level :D
You'd think with GPS and a connection to indicated airspeed, an app could automatically alarm you if your acceleration is insufficient for a given runway long before the 50% mark.
Thanks Juan! We stopped first at Heber City UT to see family and made it to Iowa City the next day (with a fuel stop in Lincoln). We're flying with my 4-year old so we may have made a stop or two more than we had to hahaha. Yes! The walking. I've been walking about 10 miles a day here :-0. We're headed back toward KGOO today and expect to arrive tomorrow afternoon. See you there!
3:40 The rule is not 70% of takeoff speed by half of the runway length, it's 70% (or better yet, 75%) of rotation speed by half of the calculated ground roll. Distance travelled is proportional to the square of speed attained, assuming constant acceleration. If you are at 70% of takeoff speed halfway down the runway, this means you will be at takeoff speed right at the end of the runway! Not good if obstacles are in the way. Also, if you are taking off from a 6,000 foot runway in a Cessna 172 and you are only at 70% of takeoff speed 3,000 feet down the runway, I don't think it will even be able to climb out of ground effect! The situation is even worse than that, because acceleration is actually decreasing as you go down the runway in a piston prop. So you will not even be at takeoff speed at the end of the runway! In any event, always refer to your aircraft manual!
One of the most most important lessons I learned from a Navy seal was the KISS principle. “ keep it simple, stupid” you’re over thinking it for a light airplane. We’re talking about runways 2000 - 5000 feet long and working to give pilots a rule of thumb that will keep them safe and almost all circumstances. This rule of thumb is that. Of course you don’t have to wait until halfway to achieve 70% on a 5000 foot runway and no you won’t runoff the end on a 2000 foot runway - we can talk physics over a beer sometime. My mentor once told me a pilot doesn’t need to know the truth only that predictable inputs chief predictable results. This rule of thumb has been used for decades in light airplanes
I noticed your flight path blazed through multiple Restricted Airspaces R 6407/R 6402 A....Just curious if you were able to do that because of filing IFR and being above 18K or ????
If I were to fly here in New Mexico, especially during the summer, I would experience that lag at takeoff for sure. Then to experience a takeoff near sea level would be different. If I get to experience a discovery flight it would likely be a high DA. I assume raising the nose wheel reduces friction and give you the angle of attack. Are stall speeds different at high density altitudes? Slow flight more sluggish?
I live in Denver, KAPA. I am so grateful I learned to fly here. Density Altitude is always a part of my flying, so is the 70/50 rule. Sometimes you can’t even consider flying during midday. Love your videos!
I did a takeoff from St. Johns, AZ during the summer. Over 8,000' DA. That was a real eye opener.
Yea we felt that recently here in Wichita at 105+ degrees, sure felt the difference!
I've flown in a 737 dozens of times. I'm used to them getting airborne with plenty of room to spare, off of 6000ft runways. It was a real eye opener watching most of the almost 11,000ft runway zip by taking off from Sana'a, Yemen in the middle of summer...and we were really scooting across the ground by the time we got up. The airport is at 7200ft ASL and in the summer, density altitude is often over 10,000ft. If you fly where there are cold winters and hot summers...the difference in performance of a 172 or Cherokee is very dramatic.
In the winter my 172M climbs 1,000FPM at full fuel and two pilots at 4606MSL. In the summer? We're lucky to see 400FPM with that load. I usually fly at minimum fuel during the summer. Absolute minimum 30 minutes to try to squeeze 800FPM initial climb out of it. We're in mountainous terrain so we need as much climb as we can get.
That happens a lot in Buenos Aires, Argentina. Summer temps are usually above 34/35ºC and sometimes would exceed 40 on some days, variating performance a lot.
That’s the best breakdown I’ve ever seen.
Thank you 🙏
Had a Piper Warrior loaded up to just under 2400 pounds. It was 30 ish degrees, pressure altitude on the ground was probably around 700 feet. We were doing a WHOPPING 300 fpm at Vy climbing through 2500!
Hi Jason, started my PPL journey back in May and stumbled across your videos (and ground school) while studying. Here on the east coast we’ve had exceptionally hot temperatures so this video comes at a perfect time to help visualize what’s going on in the PA28 I’m flying.
Thanks!
I flew closer to max gross than I ever had before over the weekend. Not a terrible density altitude, but I certainly experienced the perceived sluggishness with the extra weight. Just held rotation attitude and let her fly when she was ready
Currently in training at KFLY and in the summer it hits 9,500 Density by 10am and will often get above 10. Combine that with consistent 15kt (or higher) winds and things can get very interesting in a c172.
Clearest explanation of density altitude that I have seen or heard yet.
Thx! 🙌🏻
Awesome video, I recently experienced a sketchy take off at a short field at max gross weight that made me start paying more attention to the density altitude. Luckily I cleared the trees at the end of the runway, but the pucker factor has very high !
As your friend was calling off runway remaining his voice changed.. Fly a (non-turbo) Arrow IV out here in AZ, DA is a fact of life. Notch 'o flaps for takeoff can be almost mandatory.
I experienced a few high density altitude takeoffs in my Arrow 180, at maximum gross weight, during Oshkosh. It’s amazing how much they don’t want to climb when they’re heavy!
Jason, super informative video as always. So sorry I missed your talk at the NAFI booth! I flew in with my son and had to leave early to beat bad weather home in KY. Maybe next year!
Jason it was great meeting with you after your NAFI presentation Friday morning. Thanks for your insights and have a great life of instructing. Blue skies!
the other thing I noticed in a high DA is how long the turbo takes to spool, you could eat a lot of runway just waiting to reach max power. I hold the brakes until the turbo lights off, it took 10 seconds for me to reach 36.5" of manifold pres. last time I took off from flagstaff AZ
Thank you, Jason! Quite informative and well-explained.
November 2019 Los Alamos, NM. 10,000’ DA, 1946 85hp C-140 near gross.
Currently learning to fly the wonderful 172XP in an average of 7000-8000’DA. It’s been an absolute joy to learn this style of flying… except that one time we took up a 100hp 150 we were thinking about buying… that time wasn’t an absolute joy lol
The turbo in the P210 is a very nice thing to have at high FA
Had a takeoff from Leadville CO with DA of 13500 in a PA 28 236 with three adults and 50 gals of fuel.
yeah Leadville is the place to see that. It’s a real eye opener!
The Dakota is backdoor turbo charged with that huge engine.
i bet compared to taking off at 8000 feet at home that the 210 felt like a rocket ship taking off at 800 feet :D i havent had that "luxury" yet as florida, everywhere is < 300ft above sea level :D
You'd think with GPS and a connection to indicated airspeed, an app could automatically alarm you if your acceleration is insufficient for a given runway long before the 50% mark.
@ 5:20 there you are craning your neck instead of using your lindbergh reference... tisk tisk
Looked for you but didn't happen. What a great show
Good stuff! How many stops did you make to OSH?
Always walking at Airventure…still recovering ;-)
Thanks Juan! We stopped first at Heber City UT to see family and made it to Iowa City the next day (with a fuel stop in Lincoln). We're flying with my 4-year old so we may have made a stop or two more than we had to hahaha. Yes! The walking. I've been walking about 10 miles a day here :-0. We're headed back toward KGOO today and expect to arrive tomorrow afternoon. See you there!
3:40 The rule is not 70% of takeoff speed by half of the runway length, it's 70% (or better yet, 75%) of rotation speed by half of the calculated ground roll. Distance travelled is proportional to the square of speed attained, assuming constant acceleration. If you are at 70% of takeoff speed halfway down the runway, this means you will be at takeoff speed right at the end of the runway! Not good if obstacles are in the way. Also, if you are taking off from a 6,000 foot runway in a Cessna 172 and you are only at 70% of takeoff speed 3,000 feet down the runway, I don't think it will even be able to climb out of ground effect! The situation is even worse than that, because acceleration is actually decreasing as you go down the runway in a piston prop. So you will not even be at takeoff speed at the end of the runway!
In any event, always refer to your aircraft manual!
One of the most most important lessons I learned from a Navy seal was the KISS principle. “ keep it simple, stupid” you’re over thinking it for a light airplane. We’re talking about runways 2000 - 5000 feet long and working to give pilots a rule of thumb that will keep them safe and almost all circumstances. This rule of thumb is that. Of course you don’t have to wait until halfway to achieve 70% on a 5000 foot runway and no you won’t runoff the end on a 2000 foot runway - we can talk physics over a beer sometime. My mentor once told me a pilot doesn’t need to know the truth only that predictable inputs chief predictable results. This rule of thumb has been used for decades in light airplanes
Very timely video. Curious does your wife love aviation or just do it to support you or somewhere in between lol?
I noticed your flight path blazed through multiple Restricted Airspaces R 6407/R 6402 A....Just curious if you were able to do that because of filing IFR and being above 18K or ????
If you're IFR, you fly through whatever airspace ATC tells you to. They handle the coordination with the military.
Is there a chance your Ground School app will ever come to Android devices?
Probably someday. We are very small company and trying to stay focused right now in creating the best product possible.
If I were to fly here in New Mexico, especially during the summer, I would experience that lag at takeoff for sure. Then to experience a takeoff near sea level would be different. If I get to experience a discovery flight it would likely be a high DA. I assume raising the nose wheel reduces friction and give you the angle of attack. Are stall speeds different at high density altitudes? Slow flight more sluggish?