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Strong headwind in circuit & also windshear

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Strong headwind in circuit & also windshear

Old 17th Apr 2018, 19:37
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Strong headwind in circuit & also windshear

Good evening.

I've just returned to instructing and am looking for some advice, please?

1. Are/were there any special considerations when flying C152s/C172s on Final when dealing with a strong wind "down the runway"? E.g. 18 - 20 Kts say?

2. Same aircraft type, on Final and encountering wind shear. Say 25 Kts dropping to 3 Kts very rapidly over about 100ft.

Thank you all for your time.

Regards
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Old 17th Apr 2018, 23:19
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1. Use a bit more RPM than usual and/or consider a smaller flap setting.
2. Use an aiming point further down the runway (assuming it’s long enough) or stay in the clubhouse and do some groundschool.
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Old 18th Apr 2018, 02:49
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As a student pilot I frequently had gains 30 knot ( on the downwind and losses (with buffeting) on finalsJust do not go out of the white arc on the AS I if you do then retract the flaps immediately...as far as the loss a little nose down and a little more power, as mentioned before.

Last edited by Pugilistic Animus; 18th Apr 2018 at 03:13.
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Old 18th Apr 2018, 05:32
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then retract the flaps immediately
No.

As has been said select an appropriate amount of flap (and that could be zero) for the headwind/crosswind/runway length you find yourself facing and select an aiming point further into the field should the space be available.

As most people fly a GA aircraft well above the stall speed, I do not add anything, though there are some who would suggest you add 1/2 the gust factor. Remember, the more energy you take into the situation the more you have to lose to get out of it.
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Old 18th Apr 2018, 08:08
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Fully understanding the stall, not just the recovery drill, and the values of flap L/D are important. The time spent on this in briefing and in the air demonstrations of flap values is critical.

The lift benefit from flap can be very small in most light aircraft. Drag is the main benefit allowing a higher power to be used and a lower nose for better forward vision on the approach. Unfortunately flap destabilises the aircraft and so only a small amount of flap is advisable for turbulent conditions.

Climb requires excess thrust/power over drag, the greater this excess the greater the climb. So should a go around be undertaken then minimum drag is important and particularly when windshear is encountered.

A standard speed for the approach is 1.3 the stall speed for the aeroplane configuration and loading. In most cases a much higher speed than this is flown based on the aeroplane being at max weight. As has been made clear it is not necessary to increase the speed but of course the 1.3 safe margin should be maintained.

Going around should be regularly practised and emphasised as normal and always acceptable. The student therefore encouraged to make this decision.
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Old 18th Apr 2018, 09:58
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90 knots to 120 knots in seconds?...I'm not having a structural failure...so yes if above
Vfe retract them; the airplane doesn't just fall out of the sky if you do...better than panicking

I respect the operating strength limitations...furthermore the white arc is put there for a reason...there's a reason why you don't fly flaps extended past that white arc!

Last edited by Pugilistic Animus; 18th Apr 2018 at 10:10.
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Old 18th Apr 2018, 12:08
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Pugilistic Animus what on earth are you doing flying in winds of 90kts.

The flap limiting speeds are normally much higher than the recommended approach or climb speeds. Over stressing the airframe should not be an issue for the approach or a go around into the climb..
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Old 18th Apr 2018, 18:02
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Oh boy the winds weren't at 90 knots...the IAS was...I don't remember the winds on that day but I do remember that it was very gusty in the pattern (circuit). Actually that day my touchdown was still a greaser that I remember and no GA necessary! Johnny Crow you drop your hammer in the hole!

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Old 18th Apr 2018, 21:04
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Thank you all.

On day in question, everything was fine until suddenly at 300' on Final with full flap, I noticed the (25Kt) windsock lift near horizontally & flap like a mad thing. I'd been "suspicious" (6th sense) and had added 5Kts.

The ASI dropped by 5Kts & I lost 50' I think ending up at near full power (!!!) just to regain a sensible profile - and live. Over the keys I ended up fast - approaching Vfe - but by the Grace of God the weather conditions abated just as suddenly such that I just flew down the 7000' r/w until Vat was again reached & we landed.

I know that a Go Around was warranted but a) it happened so quick & b) I wanted down!

I said to the student that I'd made an error in not Going Around.

It was groundschool for the rest of the day.
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Old 19th Apr 2018, 04:12
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Extend the circuit upwind, way past the point where you normally turn crosswind, or you will end up doing your downwind checks and then turning base over Belgium.
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Old 19th Apr 2018, 11:16
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Originally Posted by Ascend Charlie
Extend the circuit upwind, way past the point where you normally turn crosswind, or you will end up doing your downwind checks and then turning base over Belgium.
When I was flying a light training aircraft the pre-landing checks were

RPM control ... ... Fully fine
Mixture ... ... ... Fully RICH
Induction air ... ... COLD
Fuel ... ... ... Pump on, Selector both and Contents sufficient
Flap ... ... ... As required
Hatch and Harness ... ... ... Closed and Tight
Brakes ... ... ... Off

Took less time than it does to read it and was done from memory (in which it has remained for 33 years) in about 7 seconds.
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Old 27th Apr 2018, 03:59
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I meant a 30 knot loss i.e. 60 KIAS on finals with some buffeting but no stall warning. The solution was a little nose down and a little more power will fix it for you

PS...If you're continuously exceeding the maximum flap extension speed it may not be your structural failure but the next pilot maybe!...anyone who disagrees with that ain't nothing but a jive turkey anyways

Last edited by Pugilistic Animus; 27th Apr 2018 at 15:57.
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