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04-25-2023, 12:26 PM #1
Gust Factor Margin
Sorry if I missed this in a different post. I have been unable to locate a recommended gust factor margin for the Phenom. For example wind 090 08G12KT. The FAA’s Handbook suggests adding 50% of the gust factor ((12-8)/2)=2 to VREF, so Vref+2, while some larger manufacturers POH’s suggest 50% of the steady wind speed and all of the gust (8/2)+(12-8)= 8 vref+8, sub(Username Protected)ect to a maximum (i.e 20KT). Does Embraer provide gui(Username Protected)ce?
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04-25-2023, 12:50 PM #2I don't recall seeing any gui(Username Protected)ce in the POH/AFM/FOL. I typically do half the gust factor, BUT if it is a long runway I will bump it up a bit more. (Username Protected)ust last I went into Pearson To(Username Protected)to, don't recall the exact gusts, but the left wing dropped significantly on short final and I lost some altitude during the lift vector shift. Glad I carried some extra speed.
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04-26-2023, 12:11 AM #3Out of curiosity, do you recall where you’ve seen that gui(Username Protected)ce? I can’t imagine flying Ref+20 in any (Username Protected)et or transport category airplane. Landing rollout would get really long in a hurry. That theory doesn’t make much sense to me if crosswinds were steady at 20 knots with no gusts unless there was significant shear caused by terrain, etc.
Aviation Week had a good article about all of this.
https://aviationweek.com/business-av...ef-isnt-enough -
04-26-2023, 07:08 AM #4
Hi (Username Protected), I learned it of from a friend of mine that flys a Gulfstream (G-450)…interesting article that you posted…much more in-depth that the FAA’s handbook that suggests (Username Protected)ust 50% of the gust factor…the article you posted also includes “Some aircraft manuals say you should add half the steady wind and the full gust increment to your approach speed“
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04-26-2023, 08:22 AM #5Good to add in 50% gust factor. Also, I recommend checking winds at the FAF and compare with what Tower is calling - this will give you an indication of potential shear.
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04-26-2023, 10:46 AM #6I’ve been taught half the gust factor up to a max of 10 knots added in pretty much every (Username Protected)et I’ve flown. We use the Vapp bug to display that speed and fly it on final approach.
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04-26-2023, 01:01 PM #7When I was getting my initial on the 100 at CAE, they said more than once that the POH already has enough margin in the tables that additional factors are not required. Maybe that works in the sim, but in my real world experience, especially flying around Fargo where we have plenty of gusts to deal with, I add in a margin of 50% of the gust.
Related, when it's gusty I usually always use flaps 3 as well. That may be a holdover from an earlier aircraft that seemed to really lose rudder authority with full flaps in gusty conditions, not sure if that's necessary on the Phenom. Any thoughts on 3 vs Full flaps?
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04-27-2023, 10:55 PM #9I can't speak to the P100, but I started flying a fleet of 300s and our SOP was Flaps 3 for all landings except for mountain airports. That was partially because some of our fleet did not have full flaps. I actually (Username Protected)ust had the Full Flap SB completed during my 10 year recently, so it's nice to have the option available. Full flaps in the 300 are great for steep approaches and when you really need that speed control. Flaps 3 is actually great the rest of the time.
As far as gust factor goes, Embraer says it doesn't really exist... Again, this is for the 300, you really do need ref +5 to 10 in ma(Username Protected)or crosswind/gusting conditions. And don't try for a smooth landing -- get it on the ground. -
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05-09-2023, 10:20 AM #10The training all says no gust factor needed (enough safety built in) but I will agree with those who say you need to add at least half the gust, especially for runways you are approaching that have a drop-off at the end (like my home airport B(Username Protected)C). On gusty days, the wind shear from the descending air is brutal (but actually fairly predictable). If it's 20 gusting 30 I can add 10 knots and still cross the threshold right at Vref. The first time I didn't do that I actually got a stall warning and had to GA.
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05-14-2023, 07:00 PM #11Ha, well, as to gust factor...today was pretty interesting. (Username Protected)iel and I flew our Praetor 500 LFPB CYQX KTEB today. Interesting and extremely fun flight end to end.
But on our arrival into Teterboro this afternoon after a tech stop at Gander, the afternoon WX suddenly went from calm and beautiful to flat out haywire.
Our arrival down from ALB to COATE and around to ILS 6 was as bumpy as anything I've ever flown. Violent. But the winds at TEB were freakish.
The call from the tower when were cleared to land Runway 6 was, "Winds 340 at 3 gusting 24." Huh. We had thought we heard that for the arrival ahead of us, but weren't sure it made any sense. That's mostly a pure crosswind, but the winds were also 320 variable 020 during this period, so pretty much anything goes.
What should we do about gust factor? Runway was dry so we could carry some extra speed at Vref if needed, but far from ideal. I decided to add (Username Protected)ust 4 knots gust factor to add (Username Protected)ust a bit of margin, but mostly we briefed very carefully how were were going to manage shear, manage the trhottle, PM monitor, etc becaue we didn't know how to implement "formula" on our addative for this scenaro.
Good golly miss molly. The wind callout was exactly correct. We were +/- 10-15 kts below 1000ft on final (VMC). Challenger ahead of said they had a predictive wind shear alert. We didn't. But it was pretty violent.
Nailed the landing ;-) -
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05-15-2023, 09:40 AM #12I have heard some airline pilots will use the following formula:
Vref + the gust factor + half the steady state wind if its gusting more than say 20.
As mentioned above, everytime I have asked the question at CAE or Embraer, the response is that Vref already is 1.3x Vso.
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