Slippery Runways

Airplane Deceleration on Slippery Runways What You Should Know  Mark H. Smith Boeing Air Safety Investigation

Airplane Deceleration On Slippery Runways  Agenda The Boeing Company

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Certified vs. Advisory Landing Distance Data

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Airplane Braking vs. Runway Friction

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Autobrake vs. Manual Brakes

Landing Distance Data  Data Provided by Boeing The Boeing Company

Two sets of landing data are provided. Certified Data

Advisory Data

“Dispatch” “Factored”

“En route” “Unfactored” “Operational”

Location:

Airplane Flight Manual (AFM)

Quick Reference Handbook (QRH)

Reqmt’s:

Parts 25 & 121

Part 121

Also Called:

Landing Distance Data  Data Provided by Boeing The Boeing Company

The two data sets are for different purposes and uses. Certified Data Purpose: Provide factored landing distance as required by regulators

Use: Determine landing distance requirements prior to dispatch

Advisory Data Provide actual landing distance capability of the airplane

Determine landing distance for operational decisions while en route

Landing Distance Data  Baseline Demonstrated Distance The Boeing Company

Runway Threshold

Touch Down

Air Distance

Auto-Speedbrakes Deployed Brakes Applied

Transition Distance

Stopping Distance

Stop

Landing Distance Data  Baseline Demonstrated Distance The Boeing Company

Runway Threshold

Touch Down

Air Distance

0 ft 

Auto-Speedbrakes Deployed Brakes Applied

Transition Distance

Stop

Stopping Distance

Basis for Certified Data Set Dry Distance from 50 ft

1sec

Max. Ma Manual Braking Basis Distance

Landing Distance Data  Baseline Demonstrated Distance The Boeing Company

Runway Threshold

Touch Down

Air Distance

Auto-Speedbrakes Deployed Brakes Applied

Transition Distance

Stop

Stopping Distance

Basis for Advisory Data Set Reverse 1 0 0 0 fe e t

1sec

Max. Manual Braking Basis Distance

Dry

Landing Distance Data  Baseline Demonstrated Distance The Boeing Company

Runway Threshold

Touch Down

Air Distance

0 ft 

Auto-Speedbrakes Deployed Brakes Applied

Transition Distance

Stop

Stopping Distance

Basis for Certified Data Set Dry Distance from 50 ft

1sec

Max. Ma Manual Braking Basis Distance

Basis for Advisory Data Set Reverse 1 0 0 0 fe e t

1sec

Max. Manual Braking Basis Distance

Dry

Landing Distance Data  CERTIFIED Data Set The Boeing Company

• • • •

Dry runway Auto Au toma mattic Sp Spee eedb dbra rake kes s Max ma manual br braking No reverse thrust

Stop

Basis Distance

CERTIFIED Data FAR Dry Basis Distance

Basis Distance x 1. 67

CERTIFIED Data FAR Wet / Slippery Basis Distance

Basis Distance x 1. 67 Basis Distance Distance x 1. 67 x 1. 15

Landing Distance Data  ADVISORY Data Set The Boeing Company

• • • •

Dry runway Auttom Au omat atic ic Sp Spee eedb dbra rake kes s Max ma manual br braking With reverse thrust

1000 ft

ADVISORY Data

Stop

Dry

Dry Braking

Wet

Good Braking

Reverse Basis Distance

Snow

Medium Braking

Ice Poor Braking

Landing Distance Data Summary  CERTIFIED Data vs. ADVISORY Data The Boeing Company

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Dry runway Auto Au toma mattic Sp Spee eedb dbra rake kes s Max ma manual br braking No reverse thrust

Reference Distance Stop

CERTIFIED Data

Basis Distance

• • • •

Basis Distance x 1. 67

FAR Dry

Basis Distance Distance x 1. 67 x 1. 15

FAR Wet / Slippery

Dry runway Auto Au toma mattic Sp Spee eedb dbra rake kes s Max ma manual br braking With reverse thr hru ust

1000 ft

ADVISORY Data

Stop

Dry

Dry Braking

Wet

Good Braking

Reverse Basis Distance

Snow

Medium Braking

Ice Poor Braking

Landing Distance  Advisory Data Dry

Quick Reference Handbook (QRH) contains airplane landing distance data for various runway conditions and brake configurations.

Good

Med

Poor

The Boeing Company

Landing Distance  Advisory Data The Boeing Company

QRH landing distance data is based on the notes at the bottom of the page. Relevant notes include: - two engin engine e detent detent revers reverse e thrust thrust - 1,0 1,000 00 ft ft of air air dist distanc ance e - actua actuall (unfac (unfactored) tored) dista distances nces (JAR Ops include 15% margin)

Based on these notes

Airplane Deceleration On Slippery Runways  Agenda The Boeing Company

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Certified vs. Advisory Landing Distance Data

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Airplane Braking vs. Runway Friction

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Autobrake vs. Manual Brakes

Airplane Braking vs. Runway Friction  Runway Condition Reporting The Boeing Company

• Thr Three ee met method hods s can can be use used d to to repo report rt run runway way con condit dition ion Airplane Braking Action Report Runway Description   Runway Friction Measurement 

• Ea Each ch met metho hod d uses uses a dif diffe fere rent nt des descr crip ipto torr (sca (scale le))

Airplane Braking vs. Runway Friction  Summ Su mmar ary y of Rep Repor orti ting ng Me Meth thod ods s 

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Airplane Braking Action Report

Runway Description

The Boeing Company

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Runway Friction Measurement ICAO

Better Braking Dry

Dry Wet Dry Snow

Good

Med Poor

Good

Compact Snow Wet Snow Slush Ice Wet Ice Worse Braking

Med

Poor

Airplane Braking vs. Runway Friction  Summ Su mmar ary y of Rep Repor orti ting ng Me Meth thod ods s 

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Calculated Airplane Braking

Runway Description

0. 4

Calculated 0. 3 Airplane Braking Coefficient 0. 2

μAirplane

0. 1

QRH Data

Better Braking

Dry

Dry Wet Dry Snow

Good

Med Poor

0. 0

Compact Snow Wet Snow Slush Ice Wet Ice Worse Braking

The Boeing Company

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Runway Friction Measurement 1. 0

ICAO

0. 8

Measured 0. 6 Runway Friction Coefficient0. 4

Good

Med

μRunway 0. 2

Poor 0. 0

Airplane Braking vs. Runway Friction  Decele Dec elerat ration ion Ava Availa ilable ble fro from m Bra Brakes kes The Boeing Company

Max Brakes

e.g., stand on the brake pedals

Dry Runway Better

μ -Runway (Tire Skid Point) μ -Airplane

Braking Conditions

(Braking Capability)

Slippery Runway μ –Runway

(Tire Skid Point)

initially, brakes will attempt full pressure but this would lock the wheels

 

Worse Less

Deceleration Available

More

Airplane Braking vs. Runway Friction  Decele Dec elerat ration ion Ava Availa ilable ble fro from m Bra Brakes kes The Boeing Company

Max Brakes

e.g., stand on the brake pedals

Dry Runway Better

μ -Runway (Tire Skid Point) μ -Airplane

Braking Conditions

(Braking Capability)

Method  Slippery Runway μ –Runway

(Tire Skid Point)

μ –Airplane

(Braking Capability)

Antiskid

Worse

Method  Less

Deceleration Available

More

Airplane Braking vs. Runway Friction  Decele Dec elerat ration ion Ava Availa ilable ble fro from m Bra Brakes kes The Boeing Company

Max Brakes

e.g., stand on the brake pedals

Dry

Braking Conditions

Good Med Poor

Less

Antiskid

Deceleration Available from Brakes

More

Airplane Braking vs. Runway Friction  Decele Dec elerat ration ion Ava Availa ilable ble fro from m Bra Brakes kes The Boeing Company

Decel. Available from Brakes Dry Good Med Poor

Less

Deceleration Available from Brakes

F o  o r  r r e  ef  f e     r  e re     n  e nc     e  c i n  n n e  e  ex     t  x t s e  ec    t  c t  i  io     n  o n 

More

Airplane Deceleration On Slippery Runways  Agenda The Boeing Company

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Certified vs. Advisory Landing Distance Data

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Airplane Braking vs. Runway Friction

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Autobrake vs. Manual Brakes

Autobrakes vs. Manual Brakes  Airplane Deceleration The Boeing Company

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Total airplane deceleration is affected by three factors: - Ae Aero rody dyna nami mic c drag drag - Wh Whee eell bra brake kes s - Re Reve vers rse e thr thrus ustt

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If used, the autobrake system - Tar Target gets s a dec decele elerat ration ion lev level el - Brake Brakes s applied applied as required required to reach reach target target level level

Autobrakes vs. Manual Brakes  Airplane Deceleration The Boeing Company

Braking Applied Max Manual

Drag 

Brakes 

Drag 

Brakes 

Reverse Thrust 

Autobrake Max

Autobrake 2

Less

Total Airplane Deceleration

More

Autobrakes vs. Manual Brakes  Airplane Deceleration The Boeing Company

Braking Applied Max Manual

Autobrake Max

Autobrake 2

Drag 

Brakes 

Drag 

Brakes 

Drag 

Brakes 

Drag

Brakes 

Reverse Thrust 

Reverse Thrust   Decel Target

Drag 

Brakes 

Drag 

Brakes  Reverse Thrust  Less

Total Airplane Deceleration

Deceleration level valid with or without reverser thrust

More

Autobrakes vs. Manual Brakes  Total Airplane Deceleration The Boeing Company

Decel. Available from Brakes Dry Good Med

Braking Applied Max Manual

Autobrake Max

Autobrake 2

Poor Drag 

Brakes 

Drag 

Brakes 

Drag 

Brakes 

Drag 

Brakes 

Reverse Thrust 

Reverse Thrust  Decel. Target

Drag 

Brakes 

Drag 

Brakes  Reverse Thrust  Less

Total Tot al Air Airpla plane ne Dec Decele elerat ration ion

More

Autobrakes vs. Manual Brakes  Dry Braking The Boeing Company

Decel. Available from Brakes Dry Good Med

Braking Applied Max Manual

Autobrake Max

Autobrake 2

Poor Drag 

Brakes 

Drag 

Brakes 

Drag 

Brakes 

Drag 

Brakes 

Reverse Thrust 

Reverse Thrust  Decel. Target

Drag 

Brakes 

Drag 

Brakes  Reverse Thrust  Less

Total Tot al Air Airpla plane ne Dec Decele elerat ration ion

More

Autobrakes vs. Manual Brakes  Good Braking The Boeing Company

Decel. Available from Brakes Dry Good Med

Braking Applied Max Manual

Autobrake Max

Autobrake 2

Poor Drag 

Brakes 

Drag 

Brakes 

Drag 

Brakes 

Drag 

Brakes 

Reverse Thrust 

Reverse Thrust  Decel. Target

Drag 

Brakes 

Drag 

Brakes  Reverse Thrust  Less

Total Tot al Air Airpla plane ne Dec Decele elerat ration ion

More

Autobrakes vs. Manual Brakes  Medium Braking The Boeing Company

Decel. Available from Brakes Dry Good Med

Braking Applied Max Manual

Autobrake Max

Autobrake 2

Poor Drag 

Brakes 

Drag 

Brakes 

Drag 

Brakes 

Drag 

Brakes 

Reverse Thrust 

Reverse Thrust  Decel. Target

Drag 

Brakes 

Drag 

Brakes  Reverse Thrust  Less

Total Tot al Air Airpla plane ne Dec Decele elerat ration ion

More

Autobrakes vs. Manual Brakes  Poor Braking The Boeing Company

Decel. Available from Brakes Dry Good Med

Braking Applied Max Manual

Autobrake Max

Autobrake 2

Poor Drag 

Brakes 

Drag 

Brakes Reverse Thrust 

Drag 

Brakes 

Drag 

Brakes Reverse Thrust  Decel. Target

Drag 

Brakes 

Drag 

Brakes  Reverse Thrust  Less

Total Tot al Air Airpla plane ne Dec Decele elerat ration ion

More

Autobrakes vs. Manual Brakes  Summary The Boeing Company

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Manual Brakes Dry run unw way ay:: Rev ever erse sers rs ar are e add addit itiv ive e Slip Sl ippe pery ry ru runw nway ay:: Re Reve vers rser ers s ar are e ad addi diti tive ve

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Autobrakes Dry run unw way ay:: Rev ever erse sers rs no nott add addit itiv ive e Slip Sl ippe pery ry ru runw nway ay:: Re Reve vers rser ers s may may be ad addi diti tive ve

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Landing Distance Advisory Data in the QRH includes reversers for Manual and Autobrakes