Editing Ground effect (aerodynamics) (section)

===Wing stall in ground effect===
The stalling angle of attack is less in ground effect, by approximately 2–4 degrees, than in free air.<ref name=NTSB>"The NTSB’s John O’Callaghan, a national resource specialist in aircraft performance, noted that all aircraft stall at approximately 2-4 deg. lower AOA [angle of attack] with the wheels on the ground." (from NTSB Accident Report concerning loss of a swept wing business-class jet airplane in April 2011) [http://aviationweek.com/business-aviation/thin-margins-wintry-takeoffs?NL=AW-05&Issue=AW-05_20190104_AW-05_763&sfvc4enews=42&cl=article_2&elq2=bb67d18ab5f24f3b940fbdcc9122aad6 ''Thin Margins in Wintry Takeoffs'' AWST, 24 December 2018]</ref><ref>{{Cite web|url=https://aviation-safety.net/database/record.php?id=19530303-1|title=ASN Aircraft accident de Havilland DH-106 Comet 1A CF-CUN Karachi-Mauripur RAF Station|first=Harro|last=Ranter|website=aviation-safety.net}}</ref> When the flow separates there is a large increase in drag. If the aircraft overrotates on take-off at too low a speed the increased drag can prevent the aircraft from leaving the ground. Two [[de Havilland Comet]]s overran the end of the runway after overrotating.<ref>Aerodynamic Design Of Transport Aircraft, Ed Obert 2009, {{ISBN|978 1 58603 970 7}}, pp.603–606</ref><ref>{{Cite web|url=https://www.flightsafetyaustralia.com/2019/10/reprise-night-of-the-comet/|title=Reprise: Night of the Comet &#124; Flight Safety Australia|author=Staff writers|date=October 25, 2019}}</ref> Loss of control may occur if one wing tip stalls in ground effect. During certification testing of the [[Gulfstream G650]] business jet the test aircraft rotated to an angle beyond the predicted IGE stalling angle. The over-rotation caused one wing-tip to stall and an uncommanded roll, which overpowered the lateral controls, leading to loss of the aircraft.<ref>{{Cite web|url=https://www.ntsb.gov/investigations/accidentreports/reports/aar1202.pdf|title=Crash During Experimental Test Flight Gulfstream Aerospace Corporation GVI (G650), N652GD Roswell, New Mexico April 2, 2011|website=www.ntsb.gov}}</ref><ref>From NTSB Accident Report: Flight test reports noted "post stall roll-off is abrupt and will saturate lateral control power." The catastrophic unrecoverable roll of the aircraft in the Roswell accident was due in part to the absence of warning before the stall in ground effect.</ref>