ATPL Theory: Derate and Assumed Temperature Reducion on JET ENGINE ✈ Please like, share and subscribe if you found this video useful and would like to see more :) Feel free to comment with future video suggestions bellow!
Captain Joe! .. love your channel man, in fact you where a bit of an inspiration to start mine. Who are you going to fly with? And welcome to the world of small cockpits with no space for anything XD but we do look better than Airbus haha give me a shout out on your channel :)
Amazing to see how these kinds of videos can help people in completely different stages of their aviation career. You with thousands of hours on the airbus on one side, me just before my ATPL theory exams on the other side :) Very useful.
A derated thrust setting does not allow extra thrust to be used if an engine fails. Derating uses a lower Vmca for that derate setting. Assumed temperature method (ATM) doesn’t change Vmca, therefore you can increase thrust in an engine out situation. Derating is primarily used for increasing a MTOW from a contaminated R/W, but used regularly for normal thrust reduction. ATM is used to reduce thrust to prolong engine life.
Wow. After many weeks at looking at forums. Constant confusion, I gave up. Finally came across this video. Now I realise, it's not a question of whether you understand something but rather how it's taught. Thank you. Perfect.
Ahhhh, now I get it! I've seen several videos explaining the Derated/Flex Temp concept. I understood, but I was still missing something. Your graph filled in the missing pieces for me! Thanks for your simple, yet super effective visual explanation!
Fabulous explanation. As a huge aviation fan I love to fly in the sim using real world procedures and understanding the performance calculations for both the take off and landing is crucial to the immersive experience. This video was useful to understand how assumed temperature affects the engine thrust. Thanks for sharing and safe flying.
Very well explained! I have looked for a good description of this in a few places and this is by far the simplest and easiest to understand. Keep it up!
Short and really effective explanation. Now I finally get the concept of "tricking" the engine into thinking the outside temperature is higher and the reason for which we have to do it.. Thank you so much ! :) I really hope you will find the time to make more interesting content for your channel, as you are really good in explaining things
Hello Sir, thanks for your video which has assisted me understanding the EASA Part 66 M15.2 turbine engines performance submodule. I noticed in your graph that the flat rated lines starts decreasing at 15 degrees celsius however I believe this should be 30 degrees celsius (or ISA + 15). Hope this helps
Hello, i am very happy you respond to me again, i am in adoration with airlines and airplanes since i was a child, worked as a ticket agent long time ago and my company at this time made a bankruptcy, but never had a chance to work for another company, Often i go to Pierre Trudeau airport in Montreal, Quebec, and passing hours to look at the takeoff and landing airplanes. i am now retired and my favorite hobby is FSX Flight simulator i have so much fun, and you help me so much about understanding how an airplane work. In the intenet many people put so many random numbers in the FMC and they mix up everything just to show that they can fly an airplane, bing, bang, pouf and thats it, I surely understand that a simulator is not the real life way, but i am trying to get the more as real as possible and i thank you very much sir. Lucien Paquette, Montreal, Quebec.
One of the better explanations. One of the results of derating takeoff and climb thrust is that it will generally burn slightly more fuel but this cost is usually offset 10 fold by longer on aircraft time and reduced Maint cost!!
Thanks! Already past 1 year and I cant understand that information but you helped me! Why is assumed+derated thrust method not good for contaminated rw?
Love to see a tutorial video on Flex Temp considerations at a departure airport at 8,000 feet with a temperature of 95 degrees Vs a temperature of 65 degrees
i guess you mean Fahrenheit?! i dont really know what that ecuates to, but the "H's" are bad for performance, high hot and humid. all decrease air density and hence performance degrades. Relating to engines a high temperature means you have to be careful not to exceed EGT temps, hence the need to derate. Lots of factors would be taken into consideration though. Runway length, aircraft weight etc....
Hello PilotEd, just a small correction if i am not mistaken, i think for a reduced thrust take off the 24k and further more the 22k will start derated (the thrust reduced by EEC) at higher temperatures, not at the same 15C as the 26k
Very well explained! Maybe i would have spent a couple of minutes more on why the thrust rating drops when departing ISA sea level conditions. Enjoy flying the 737ng 🙀
Very nice video! :) I'm beginning my adventure with civil jets and I spent a lot of time seachring answer on this subject (thats of course ok, because i tried to sort this knowledge up in my head and got the basics), but your video finally led me to understand how it works in practice. Anyway, i have one question to you. At the end of the video you said that despite de-rate + assumed temperature were selected, at any time you can reach Max thrust if in need. It is the: - Max rated thrust (f.e. 26k like in video), - Max de-rated (f.e. in video we used 24k), - or is it MAX operating limit (f.e. in 737NG 27.1k)? And a second smaller question - maybe i'm mistaken, but this reduction of thrust after FRT done by EEC isn't in fact reduction of N1 speed? (less dense = engine can't produce thrust without enough amount of air = there is no need to spin N1 so fast?) Thanks in advance and have a nice day! :)
A great video . However Few doubts 1- is it possible to select these pre set de rated thrust ? I mean how we do it and this selection must be different before every takeoff due ambient atmospheric conditions and runway length 2- inspite of this flat rating concept why can’t we put the thrust lever at less power setting to avoid excess thrust
thanks heaps for your videos. im PPL working soon on ATPL.. quick question, higher temperature means less air density.. with prop planes this means you lose performance.. with jet planes not? also why do you have to fool the fmc by entering a higher temperature so it decreases thrust.. ? isnt there a way to put in those extra factors like a longer runway etc? thanks!!
Thats right yes higher temperature air expands and becomes less dense. this means degrading performance for all types of aircraft. remember the 3 "H's" HIGH/HUMID/HOT are all bad for performance! jet and piston. Thanks for watching new videos coming soon.
Hi! Really good video! I have one question though. How is the required thrust calculated? Is there some sort of table in the QRH or FCOM where you can see how much N1 is needed for a specific weight and runway length?
The problem is as many others have referred to. Is that reduced thrust takeoffs actually increases fuel consumption so you should recut the video and fix this. In talking to maintenance about this .The amount is minimal because of the time difference it takes to get to 15k where this is automatically phased out. If you need a reference Goto your 737 FRM or FCOM on reduced thrust . It’s right there.
i dont remeber where i read, but if you use more thrust you need to use a greater V1 (due to the Vmcg) and in some cases this turn into a bad idea to use more thrust.
Hi Ed, nice Vid, but I have comments concerning the technical part:1. Pls mention the type you're flying. On MD11 there is no derate, only flex. On Airbus, usually you can have both, although derate is hardly used, but a combination is not allowed. On Boeing, both is available and can be used, also in combination.2. Using a derated Takeoff thrust, usually you aren't allowed to advance the thrust beyond that point. By using a derated trust setting, the performance parameter are also affected, means for example v1/vr/... AND Vmcg/Vmca (minimum control speed). That's the difference to the assumed temperature procedure.3. Derated or Flex Thrust settings will not save any fuel. That's commonly misunderstood but unfortunately told that way by some training instructors.
Its to do with engine ware more than fuel savings mate!, if we dont need the full bangs from the engine we can use ATR and derate to bring the engine down, saving on wear and tear. Im on the 737-8 NG by the way. thanks for watching
I have a question. Why do we use an assumed temperature to get the DE-RATE config for a 70ton takeoff instead of just setting the fms for a 70t takeoff? In other words, why do i need to change the temperature for an assumed temperature instead of just selecting the correct thurst(de-rate) required?
well is that true that for the derate thrust method (unlike assumed temperature method ) the thrust can't be overridden by using TO/GA setting? the engineer power up to the maximum thrust permitted under the de-rate! that's why we need an additional rating isn't it?
Good video. However a bit too simplistic, it lacks the explanation why derated takeoff thrust is considered a takeoff operating limit since VMCG and VMCA and stabilizer trim settings are based on derated takeoff thrust while reduced takeoff thrust (assumed temperature) is not considered a takeoff operating limit. So while selecting only the latter, the thrust levers might be advanced to full rated takeoff thrust during the takeoff run. Would be nice to include this explanation.
i dont really understand the wording of your question, but yes if the temp is above 15 degrees the EEC will reduce the trust. This saves exceding RGT temperatures. thanks
wait. 2:32. you say the EEC reduces the thrust when the oat is RISING? shouldn't it be the other way around? (Hot temp- performance degrades - the eec compensates?)
Flat rated engine is designed to achieve the same level of thrust up to a certain temp, then for higher temps, the level of thrust decreases as a function of OAT. This gives identical performance over the flat portion of the OAT range making the performance predictable. But for higher OATs, it stops the EGT continuing to increase. The EGT is the key part, higher temp you don't want more thrust because you will exceed EGT limits. Hope thats understood. thanks for watching
Hello sir, For takeoff are the pilots engaging FULL THRUST, or 40 % then 70-80 % as per Boeing 737 and let it there till the lift off, and then making some adjustment but without touching the throttles ???? Thank you sir, Lucien Paquette.
@@PilotEd on the 787 there is what is called, thrust ramping, the EEC slowly increases the thrust until reaching the T/O thrust (sometimes reached until 65 kts), and it is observed when we need to compensate for crosswinds, low groundspeed, high alt airport, high ambient temp....etc
Hello sir, thank you for your videos. i understand about the assumed temperature, but when i put it in the fmc, sel oat, how can i know witch derate to choose ? 24k,22k,, to1, to2, clim1,clim2, i am mixed up with this, and i would be very happy to understand it more, also...do we have to choose assumed temperature and derate one or the other, or both at the same time thank you very much sir, lucien paquette
haha, im guessing your a flight sim man! if you do the performance calculations for your runway and weather conditions, it will give you a derate, then you can assume, again as calculated. In my company we have a nice ipad that does it for us, but if it fails we can still revert to the old paper way from the manual. QRH. thanks for watching
FMC we can select a derate 22/24/26k even 20 in some versions, and also an assumed temp. Of course at any point we can manually push the thrust levers forward to max :) thanks for watching
Sorry, I am still very confused. As you have mentioned at the start of the video. If the actual take off power required is (lets assumed 23K on the Thrust axis), why don't we just select 23k of thrust at take off. Why do you still have to pick 24K.
I’m sorry but the flat rating means the engine can make RATED thrust up to a given temperature. It’s not the EEC’s reducing the thrust, it’s the air density that’s reducing the thrust. The engine can only make rated thrust up to a mfg. defined air temperature limit
I don't understand one thing about derate thrust, in ATPL's questions, they say that using derate we can't apply TOGA, while using reduced thrust we can...Why? I'm a little confused ahahah
Well, yes the temperature does affect the engine performance, however if its -10 there are other factors to take into account such as anti-ice and would prob not use temp assumption on the engine because we would have de-iced. but cold weather generally offers more performance and hence more margin to derate. But it depends on so many factors. weight, weather, runway etc...
Cute "bad for the enviroment" 😂😂 one of the tasks of a pilot is to make money, this is all about cash! Let the manufacter think about enviroment and lets focus on making money. If they ask you why we use de-rated or reduced thrust in an interview don't say enviroment, say money! Airlines want you to think about money and costs reduction. Your pay check is so high because your job is to take care of any shit that could happend during the operation (so you need so save lifes and save the very expensive million dolar aircraft) and earn money! If you don't make money you lose your job. Simple!
