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-   -   Ground Speed Mini and Strong Headwinds (https://www.pprune.org/tech-log/273542-ground-speed-mini-strong-headwinds.html)

Wino 28th April 2007 14:19

MAX,

I think we are closer than you think in our approaches to the aircraft.

I will NEVER select a speed lower than ground speed mini with the autothottles engaged near the ground. If for some reason I need a slower speed (ATC or flap constraint) then I will disconnect the autothrottles and fly that slower speed, declaring it verbally but leaving the groundspeed mini target up as a representation of the inertial state of the aircraft ( hint that more power will be needed, possibly soon)

I will never select a slower airspeed than groundspeed mini with the autothrottles engaged because of the long slow deliberate throttle movements programed into the autothrottles. If putting myself in a situation where rapid throttle response might be required, then I make sure rapid thottle is available...

Cheers
Wino

Wingswinger 28th April 2007 17:49

Max,

I appreciate the differences between 319s at 55t and 321s at 75t. I've flown all variants within the 320 family and both engine types.

I agree with you about windshear protection in managed with G/S mini. Here's an extract from one of my earlier posts:


I must stress that I am talking only about approaches in strong gusty winds and their associated low-level turbulence, not about approaches in conditions in which a genuine windshear could be encountered (as opposed to gusts of +/-10 to 15kts, for example).
Should there be a weather front passing through the airfield or large Cb in the vicinity, rest assured - I'd be in managed. I'd also be landing in Config 3.


If you miss yout touch-down-point, you go-around so nothing unsafe there.
Being commercially minded, I'd rather not give the passengers a go-around and an extra approach they haven't paid for if I can avoid it! Adopting selected speed on very short runways in certain circumstances can reduce the likelihood of going around. It's horses for courses.

Tree 29th April 2007 02:54


Maybe in theory but not in real life, have seen the managed speed above 177 KTS on more than one occasion.
Ditto here. With wind speed above 60k the managed speed stays well above Vfe next for all flap configurations. The solutions are manual thrust or a/t selected speed and fly 1/2 headwind plus all gust to max 20k. Works for me.
G/S mini in high or gusty winds is like a lawn mower with a really defective governor.

alexban 29th April 2007 14:32

One question, not knowing much about the Bus:
I've read the previous post and I wonder about you're ideea of not being so safe if flying selected due to possible low energy.
What will you do if flying on a busy airport, with high winds (for ex LHR ) and APP instructed you to maintain 160 kt? As I understand ,if flying managed , higher head wind will give a commanded IAS of maybe 175 kt ,am I right?
If the plane ahead ,or behind you , is a 737 , it will keep 160 kt IAS , so the separation will be compromised,I guess.

Wingswinger 29th April 2007 17:30

You fly the selected speed as instructed by ATC and go managed at 4 miles. Speed regimes at busy airports in the UK are (generally) downwind 220kts; base, intercept and establishing on ILS 180kts then 160kts to 4DME. Separation is not compromised providing one is fairly accurate about flying the ATC speeds.

punchus 1st May 2007 13:31

As wingswinger has said:
"I appreciate the differences between 319s at 55t and 321s at 75t. I've flown all variants within the 320 family and both engine types".

Anyone any thoughts on the problem as it occurs on a 330 at 170-175 tonnes.


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