A Pilot's Guide to Inflight Icing
Module I - Before You Fly
Aerodynamics of Icing
Section: Performance Effects
Start This SectionPerformance Effects Aerodynamics of Icing
When an aircraft is contaminated with ice, its performance is degraded. Ice accretion will:
- Decrease climb rate
- Decrease cruise speeds
- Increase stall speed
- Decrease service ceilings
- Decrease missed approach performance
- Increase fuel consumption and decrease maximum range
Ice contamination will affect performance
Performance Effects Aerodynamics of Icing
The biggest degradation of performance usually occurs within the first few minutes of ice accretion.
Tests conducted at NASA Glenn Research Center on several modern airfoils demonstrated that, in some instances, exposure to clear icing for 2 minutes could double the drag, reduce the maximum lift by 25%-30%, and reduce the critical angle of attack by 8 degrees (which would correspond to a substantially higher stall speed).
Two-minute ice accretion on a business jet airfoil
Related Information
CLEVELAND, OHIO
FEBRUARY 17, 1991
DC 9-15
After flying through rime icing conditions on a night approach, the aircraft remained on the ground for 35 minutes as dry snow fell continuously. The crew did not inspect the exterior or de-ice the aircraft. Immediately after take-off, the aircraft stalled and rolled into the ground. The NTSB report theorized that the anti-icing system had been used on the approach and the falling snow had melted and refrozen while the aircraft was on the ground and the anti-icing system automatically de-activated. The report also stated, "According to the manufacturer, a wing upper surface contamination that is only 0.014 inches thick (about equal to the roughness of 80-grit sandpaper), can produce a 25 percent loss of wing lift."
BARTER ISLAND, ALASKA
MARCH 12, 1985
de HAVILLAND DHC-6
The aircraft was on a flight from Deadhorse, Alaska to a temporary winter landing strip at Barter Island, Alaska. While attempting a go-around the aircraft crashed about 1/2 mile from the departure end of the runway. Marginal weather conditions prevailed with icing reported. Investigation revealed that both wing leading edges were covered with approximately 3/16 inch of ice and the switch for the deicing boots was in the "off" position.
Rick Glewwe, RJ-85 Pilot
Performance Effects Aerodynamics of Icing
Airfoil Specific Demonstration*
To better understand the effects of different ice shapes on different airfoil sections, please review the Airfoil Specific Demonstration content on the following pages. Browse images and tracings of ice accretion at three different exposure times. The airfoil sections represented are:
General Aviation - a general aviation wing with natural laminar flow
Business Jet - a business jet thin wing
Commercial, Tail - the horizontal tailplane of a commercial transport aircraft
Each section contains images and data relating to:
Ice type - clear, mixed, or rime.
Effect on performance - drag, lift, or stall angle.
*The Airfoil Specific Demonstration reports data from tests conducted on 2-D airfoil sections in the Icing Research Tunnel at NASA Glenn Research Center. These data are representative of, but cannot mimic exactly, the actual performance of a 3D wing or tail in flight.
Performance Effects Aerodynamics of Icing
General Aviation
Select any of the 3 labels below to view associated images.
2 MIN
Clear Ice
6 MIN
Clear Ice
22 MIN
Clear Ice
2 MIN
Mixed Ice
6 MIN
Mixed Ice
22 MIN
Mixed Ice
2 MIN
Rime Ice
6 MIN
Rime Ice
22 MIN
Rime Ice
Accretion Conditions: IAS=130 kts, AOA=0.3 deg, LWC=0.54 g/m3, MVD=20 microns
SAT= -5°C (Clear), -10°C (Mixed), -15°C (Rime)
Accretion Conditions: IAS=130 kts, AOA=0.3 deg, LWC=0.54 g/m3, MVD=20 microns
SAT= -5°C (Clear), -10°C (Mixed), -15°C (Rime)
Accretion Conditions: IAS=130 kts, AOA=0.3 deg, LWC=0.54 g/m3, MVD=20 microns
SAT= -5°C (Clear), -10°C (Mixed), -15°C (Rime)
Performance Effects Aerodynamics of Icing
Business Jet
Select any of the 3 labels below to view associated images.
2 MIN
Clear Ice
6 MIN
Clear Ice
22 MIN
Clear Ice
2 MIN
Mixed Ice
6 MIN
Mixed Ice
22 MIN
Mixed Ice
2 MIN
Rime Ice
6 MIN
Rime Ice
22 MIN
Rime Ice
Accretion Conditions: IAS=175 kts, AOA=6.0 deg, LWC=0.5 g/m3, MVD=20 microns
SAT= -5°C (Clear), -10°C (Mixed), -15°C (Rime)
High Speed, Low AOA configurations: IAS=250 kts, AOA=1.5 deg
Accretion Conditions: IAS=175 kts, AOA=6.0 deg, LWC=0.5 g/m3, MVD=20 microns
SAT= -5°C (Clear), -10°C (Mixed), -15°C (Rime)
High Speed, Low AOA configurations: IAS=250 kts, AOA=1.5 deg
Accretion Conditions: IAS=175 kts, AOA=6.0 deg, LWC=0.5 g/m3, MVD=20 microns
SAT= -5°C (Clear), -10°C (Mixed), -15°C (Rime)
High Speed, Low AOA configurations: IAS=250 kts, AOA=1.5 deg
Performance Effects Aerodynamics of Icing
Commercial, Tail
Select any of the 3 labels below to view associated images.
2 MIN
Clear Ice
6 MIN
Clear Ice
22 MIN
Clear Ice
2 MIN
Mixed Ice
6 MIN
Mixed Ice
22 MIN
Mixed Ice
6 MIN
Rime Ice
22 MIN
Rime Ice
30 MIN
Rime Ice
Accretion Conditions: IAS=250 kts, AOA=0.7 deg, LWC=0.4 g/m3, MVD=20 microns.
SAT= -10°C (Clear), -15°C (Mixed), -20°C (Rime)
Accretion Conditions: IAS=250 kts, AOA=0.7 deg, LWC=0.4 g/m3, MVD=20 microns.
SAT= -10°C (Clear), -15°C (Mixed), -20°C (Rime)
Accretion Conditions: IAS=250 kts, AOA=0.7 deg, LWC=0.4 g/m3, MVD=20 microns.
SAT= -10°C (Clear), -15°C (Mixed), -20°C (Rime)