Wednesday, February 26, 2020

APPROACH SPEED AND THRESHOLD CROSSING SPEED - The term "approach speed" can be slightly misleading. It's not the speed you'll fly all the way to the runway. Instead, think of your final approach as three stages of speed changes. Following this model will give you the best speed control for nailing your touchdown point: Final Approach Speed, Slowing To Threshold Crossing Speed, Slowing During Your Flare. Most aircraft flight manuals recommend a speed. However, if your manufacturer doesn't list a final speed in their flight manual, the FAA recommends that you fly 1.3 x Vso. As you turn final, set pitch and power for your final approach speed, and stabilize your descent to the runway. If you're constantly changing throttle settings to adjust altitude and airspeed, you might want to consider going around to try again. A good rule of thumb for light, single-engine piston airplanes is to check that you're flying a stable approach at least 200 feet above the ground. Are you flying the correct approach speed, configured, on centerline, with minimal power changes, and a normal sink rate?

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PrimaryApproach Speed And Threshold Crossing Speed
What's The Difference Between Approach Speed And Threshold Crossing Speed?
By Swayne Martin




If you don't fly the right speeds on final, you can miss your touchdown point by hundreds of feet, every time. Here's what you need to know...
Flying Your Approach
The term "approach speed" can be slightly misleading. It's not the speed you'll fly all the way to the runway.
Instead, think of your final approach as three stages of speed changes. Following this model will give you the best speed control for nailing your touchdown point:
Final Approach Speed
Slowing To Threshold Crossing Speed
Slowing During Your Flare
How Approach Speed Is Calculated
How fast should you fly on final? Most aircraft flight manuals recommend a speed.
However, if your manufacturer doesn't list a final speed in their flight manual, the FAA recommends that you fly 1.3 x Vso (stall speed in a landing configuration).
For a couple examples, the C172S POH recommends 60-70 knots with full flaps for a final approach speed.
As for the Cirrus SR22T, they recommend 80-85 knots on final, and 79 knots crossing the threshold.
Stabilize Your Approach As Early As Possible
As you turn final, set pitch and power for your final approach speed, and stabilize your descent to the runway.
If you're constantly changing throttle settings to adjust altitude and airspeed, you might want to consider going around to try again.
A good rule of thumb for light, single-engine piston airplanes is to check that you're flying a stable approach at least 200 feet above the ground.
Are you flying the correct approach speed, configured, on centerline, with minimal power changes, and a normal sink rate?
Slowing To Threshold Crossing Speed
Now that you're stabilized on final approach speed and glidepath, you need to prepare for your next phase of the landing: threshold crossing speed.
Once you have no doubt that you'll make the runway, just before the threshold, slowly begin reducing the throttle.
Not all aircraft manufacturers have a recommend threshold crossing speed, but as a rule-of-thumb, it should usually be around 5 knots slower than your final approach speed in a light aircraft.
As you cross the threshold, keep reducing throttle, and start your transition to flare by slowly pitching up.
Technique for how and where to reduce power can change dramatically based upon each different type of airplane you fly.
The best way to hone your skills in your plane is to go out and practice!
Continue Slowing In The Flare
As you reach the final stage of speed change during your flare, you should be continually slowing the aircraft.
In many single-engine piston airplanes, you'll be at idle power during the flare.
Your goal is to touch down just a few knots above stall speed.
With just a few knots of airspeed to lose, you'll give yourself the best shot at nailing your touchdown point by being on-speed in the flare.
If you continue descending to the runway close to approach speed, the extra knots of speed will be hard to bleed off during the flare because of ground effect.
Exception: Gusty Winds
You'll fly a faster approach speed than recommended with strong, gusting winds.
Adding half of the gust factor to your final approach speed will ensure you're flying well above stall speed if you encounter wind shear. That's a good thing.
Because of this, you may also want to consider flying a faster threshold crossing speed and flare speed.
The extra knots of airspeed will give your flight controls more effectiveness, helping with crosswind control.
What do you think? How do you slow down on short final? Tell us in the comments below.
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Swayne Martin
Swayne is an editor at Boldmethod, certified flight instructor, and an Embraer 145 First Officer for a regional airline. He graduated as an aviation major from the University of North Dakota in 2018, holds a PIC Type Rating for Cessna Citation Jets (CE-525), and is a former pilot for Mokulele Airlines. He's the author of articles, quizzes and lists on Boldmethod every week. You can reach Swayne at swayne@boldmethod.com, and follow his flying adventures on his YouTube Channel.
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