trollifail 0 Posted May 1, 2018 Share Posted May 1, 2018 Maybe I'm wrong, but I would say unable, because to calculate the required track miles I multiply my FL for 3/10 and add a mile for each 10 knots above 250kt. So 150 * 3 / 10 = 45 which is much higher than 24 without considering the speed. Anyway I think that the ATC should reason the same way and sounds strange that he asked if 24 is enough given a calculated track miles of 45. Link to comment Share on other sites More sharing options...
CRJ900 335 Posted May 1, 2018 Share Posted May 1, 2018 vor 7 Stunden , Mathijs Kok sagte: Mmmm, that will have a very small effect, hardly noticeable. No there is a MUCH bigger reason, something that plays a major part in the yes/no decision. That is actually the MAJOR effect (downside) of sharklets. The reduced induced grad and thus reduced descent rate while maintaining or reducing the speed. Ask any Airbus pilot who has flown the sharklets. That's aerodynamics 101. Link to comment Share on other sites More sharing options...
Alexander Wurz 42 Posted May 2, 2018 Share Posted May 2, 2018 If we consider the following: 15000 feet indicated at QNH 1030 and standard atmos temperature of -15°C If we consider a "standard" descent speed of 290 IAS we get a TAS of 365 Kts. 30 Kts Headwind means 335 Kts Groundspeed. (used http://indoavis.co.id/main/tas.html ) How many minutes for 24 miles to calculate: (24 miles / 335 Kts) * 60 = 4,298 Minutes so to go from 15000 feet to 3000 feet we need to decent 12000 feet in ~ 4,3 Minutes = 2790 feet/minute decent rate. The Question is, if the Airbus is capable of this rate below FL 100 according to https://www.skybrary.aero/index.php/A320 until FL100 a decentrate of 3500ft/min is possible with 290 Kts IAS, but I do not have any info found on the sharklet version oder belo FL100 Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted May 2, 2018 Author Aerosoft Share Posted May 2, 2018 20 hours ago, A346 said: It's probably a limitation of speed brake usage or gear extension/gear down performance for models with sharklets. But hard to find the exact reason without access to the FCOM/FCTM. Bingo! Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted May 2, 2018 Author Aerosoft Share Posted May 2, 2018 14 hours ago, CRJ900 said: That is actually the MAJOR effect (downside) of sharklets. The reduced induced grad and thus reduced descent rate while maintaining or reducing the speed. Ask any Airbus pilot who has flown the sharklets. That's aerodynamics 101. Ahh well, this question was made by an Airbus pilot and he told us the sharklets do not matter a lot. They mainly increase efficiency. Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted May 2, 2018 Author Aerosoft Share Posted May 2, 2018 6 minutes ago, Alexander Barger said: If we consider the following: 15000 feet indicated at QNH 1030 and standard atmos temperature of -15°C If we consider a "standard" descent speed of 290 IAS we get a TAS of 365 Kts. 30 Kts Headwind means 335 Kts Groundspeed. (used http://indoavis.co.id/main/tas.html ) How many miles per minute to calculate: (24 miles / 335 Kts) * 60 = 4,298 Minutes for 24 Miles so to go from 15000 feet to 3000 feet we need to decent 12000 feet in ~ 4,3 Minutes = 2790 feet/minute decent rate. The Question is, if the Airbus is capable of this rate below FL 100 according to https://www.skybrary.aero/index.php/A320 until FL100 a decentrate of 3500ft/min is possible with 290 Kts IAS, but I do not have any info found on the sharklet version oder belo FL100 That's a reasonable assumption. But the important fact is that the flight crew did not need the calculations. They had the mental picture and could reply almost immediately. Link to comment Share on other sites More sharing options...
Alexander Wurz 42 Posted May 2, 2018 Share Posted May 2, 2018 1 hour ago, Alexander Barger said: If we consider the following: 15000 feet indicated at QNH 1030 and standard atmos temperature of -15°C Of course I meant QNH103 for FL150 @Mathijs Kok And that amazes me, to be honest. To be that highly trained to have a mental picture of what the aircraft can do at any given moment Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted May 2, 2018 Author Aerosoft Share Posted May 2, 2018 Pilots are some of the best trained professionals and they never stop training and never stop being tested. To some degree almost everybody can do it. When you drive your car you do not calculate all the time if you are able to make a turn, will be able to stop or if that car merging with the highway will be crashing into you. There are processes in our mind that constantly updates these things as long as you are not 'dropped' into the situation. It take time to build up the mental picture. When it DOES happen suddenly humans are actually pretty bad at these things. Our brains are terribly slow to react to new information but incredibly good at extrapolating events. Link to comment Share on other sites More sharing options...
Guest Posted May 2, 2018 Share Posted May 2, 2018 vor 3 Stunden , Mathijs Kok sagte: That's a reasonable assumption. But the important fact is that the flight crew did not need the calculations. They had the mental picture and could reply almost immediately. And that's why you get trained for 2 years and throughout your whole carreer. Link to comment Share on other sites More sharing options...
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