Regional Airline Operations on Contaminated Runways · on Contaminated Runways ... for landing on slippery runway with and ... condition (wet, contaminated), engine failure in attempted

Nihad E. Daidzic, Ph.D., Sc.D., ATP/CFIIAssociate Professor of Aviation

Adjunct Associate Professor of Mechanical Engineering

WATS 2011April 19-21, 2011, Orlando, FL, U.S.A.

Day: 2 Conference Stream: RATS Session: 6.3

Regional Airline Operations on Contaminated Runways

• It is my pleasure to be at the WATS 2011 conference and to present here. I would like to thank all participants for coming to this session and my fellow speakers in this and in the other sessions.

• Let me also thank Halldale Media for organizing such a wonderful conference. In particular, I would like to thank Mr. Andy Smith, President of Halldale Media Group, Mr. Chris Lehman, WATS conference chair and editor of CAT magazine, and our session moderator.


CONTENT

• Introduction

• Landing veer-offs

• Go-around decisions after touchdowns (PNR)


MOTIVATION

• Landing overruns and veer-offs have caused 46 accidents in commercial air transportation (large transport category) in January – April 2010 period alone (Source: WATS 2010 - Capt. John Bent).• In the 17 months between October 2004 and February 2006, seven airplanes skidded off runways in USA and Canada alone, killing eight people, injuring another 34 and destroying four aircraft for hundreds of millions of dollars in losses. (Edmund Pinto “Aviation Daily” 03/03/2006).• In the period 1958 to 1993 about 120 landing accidents occurred (in average 5 every year) in US alone due to the wet and slippery runways leading to loss of life and damage exceeding several billion dollars (NASA LRC).• Of all (large transport) aircraft accidents/incidents, runway landing accidents occur most frequently. It is #1 cause of accidents in air transportation. Although not as lethal as CFIT and LOC-I, runway accidents do lead to injuries, damage/destruction of the aircraft, bad PR, etc.


OBJECTIVE

• To understand forces acting on and airplane response when operating on slippery surfaces (ice, hydroplaning, etc.) with X-wind. That is veer-off landing scenario

• To understand dynamics of airplane deceleration and acceleration with subsequent TOGA on a slippery runway. This is the runway PNR scenario. Understanding decision making process is quite critical here.


INTRODUCTION

• Contaminated runway is, per definition, a runway whose surface is at least 25% covered with the water film in excess of 3 mm (about 0.12 inch), or its equivalent in slush, compacted or wet snow, or ice.

• Slush 5 mm deep (density 700 kg/m3 or 0.7 g/cm3) has equivalent water-film thickness of 3.5 mm.

• No significant reduction in runway accidents – overruns, veer-offs, etc., despite many industry efforts (ALAR, etc.)


Reference from Timothy W. Neubert: Runway Friction Measurement & Reporting Procedures, 2006 Airfield Operations Area Expo & Conference, April 9, 2006 Session 3

In other countries CRFI (Canadian Runway Friction Index) and μ(“mu”) are used more frequently. The US system is very subjective!


Landing Rules (FAR, JAR, ICAO) Nothing in Part 25 airplane certification

FAR 121.195FAR 135.385



aavL

vavL

v

a

∆

−=∆

∆

=∆

2

2

2


DLDDLDRWLDRDLDDLDR

⋅=⋅=⋅=

92.115.167.1

ftWLDRftDLDR

ftDLDftL

ktsvlbsMLW

AIR

REF

64375597

33581750130

000,150

==

====


DLDDLDRWLDRDLDDLDRWLDR

DLDDLDRWLDRDLDDLDR

⋅=⋅=⋅=⋅=⋅=⋅=

⋅=

46.260.1300.230.12

77.115.1154.1

Airplane decelerating devices/systems:

• Brakes (Tire/Surface friction braking)• Reverse Thrust (max. about 40% of max. fwd. thrust)• Aerodynamic drag (high AOA, speed brakes, parachutes)• Uphill runway landing (gravity-assist)• Mechanical (Arresting hooks and cables, etc.)

Airport/Runway decelerating systems:

• EMAS (Engineered Materials Arresting System )


Landing Veer-offs


DC-9 Aircraft Wet Runway Landing Veer-off Accident Reynosa, Mexico; October 6, 2000.



Schematic drawing of the landing roll with and without thrust reversers on slick runways and significant crosswind. Tire cornering (lateral) force is opposing sideways push by X-wind.


2

21

−⋅=

dtdyuScF xwrefDxwsideways ρ

Lateral displacement as a function of time for landing on slippery runway with and without lateral touchdown drift and/or displacement. Significant crosswind of 30 knot existed and no thrust reversers (average friction coefficient 0.08).



Lateral displacement as a function of time for landing on slippery runway with and without lateral touchdown drift and/or displacement. Significant crosswind of 30 knot existed and thrust reversers were used (average friction coefficient 0.08).

Crosswind component

[knots]

Lateral displacementafter 10 seconds(no reverse) [ft]

Lateral displacement after 10 seconds

(with reverse) [ft]

0 0 0

5 0 0

10 0 0

15 0 0

20 0 8.2

25 0 29.7

30 12.98 55.98

35 44.04 87.05

40 79.88 122.89

45 120.49 163.5

Landing on a slippery surface (average friction coefficient 0.08) for variable crosswind strength and zero sideways displacement, speed, or acceleration on touchdown for CRJ700 with GE CF34-8C5 engines. As long as the tire cornering force can resist wind drag there will be no sliding and no lateral displacement. We can assume that the downwind main landing gear is 40-65 ft from the runway edge. Of course, without corrective action the lateral displacement will increase nonlinearly with time (red highlights specify likely veer-off).


Go-Around decisions after touchdown – the “Runway” Point-of-No-Return (PNR)


Attempts of Go-Around after touchdown can be fatal. For example, 37 out of the 88 on board were killed in attempted go-around of an American Airlines Boeing 727-100 after a long touchdown at STT (St Thomas, US Virgin Islands) in April 1976. The airliner touched down about 3000 ft from the threshold of the 4650-ft runway. After abandoning the braking effort, the captain attempted to go around. Then, realizing (fortunately) that it would be impossible to lift off (using whatever is left of the runway), the captain changed his mind and tried to stop. The 727 exited the runway at high speed, with many fatalities occurring in the ensuing crash and fire.

AA Boeing 727-100 Accident


Recent NTSB ruling (ID: DCA08MA085) has confirmed that pilots of a Hawker Beechcraft 800A (BAe 125-800A) registration N818MV in Owatonna (KOWA in MN) on July 31, 2008 attempted unsuccessfully a go-around after long touchdown and poor braking efforts (NTSB final ruling says that pilots did not use brakes for 8 seconds after touchdown?) and simply didn’t attain the flying speed to escape the ground effect, stalled, and crashed about 1500 ft beyond the runway. A 1000-ft long impact and crash deceleration distance existed beyond 1500 touchdown in the corn field. All aboard lost their lives (2 pilots + 6 passengers). Eyewitnesses said that the airplane tried to takeoff after it already touched down attempting to land.

Hawker 800A at KOWA on 07/31/2008


These two unfortunate accidents clearly show that operators need to have SOPs and clear policy on if, how, and when to execute go-around after touchdown. Decisions about possible go-around need to be made before actual touchdown (just like v1-action speed).

Need SOPs


The point on the runway defined by airplane airspeed is the dynamic location of the last-chance go-around attempt after actual touchdown and landing roll. This is go-around PNR (Point-of-No-Return) after which it is far better to accept possible overrun then attempt go-around/touch-and-go takeoff.

Exact PNR location will depend on many factors: airspeed, wind, distance, touchdown location, existence of thrust reversers, runway condition (wet, contaminated), engine failure in attempted go-around, etc.

Landing Roll PNR


Executing “go-around” aborted (rejected) landing roll after touchdown can be “safely” attempted only if initiated before the PNR. In this example we did not include departure obstacles. We assumed that the airplane will lift-off by the end of runway. Configuration change consumes 1000 ft with or without thrust reversers. PNR is the point by which the action to go-around MUST be initiated. No provision for engine failure in “Acceleration” region. The airplane may or may not exit the runway in slowdown roll (Not to Scale!).



• This problem is inverse of the Accelerate-Stopproblem.

• We can also call it Stop-Accelerate (or Decelerate-Accelerate) problem

VLOF [knots]Air-Distance (Touchdown)

1,500 ft 2,500 ft 3, 500 ft

12077.2 kts 93.7 kts 107.6 kts

11.3 s 6.9 s 3.3 s

13092.0 kts 106.2 kts 118.7 kts

10.0 s 6.3 s 3.0 s

140105.6 kts 118.2 kts 129.6 kts

9.1 s 5.7 s 2.7 s

Table 1: The calculated go-around (aborted landing roll) groundspeed and the maximum safe elapsed time before go-around is initiated with a 1,000 foot “indecision” distance, hydroplaning surface and maximum thrust reversers deployed (0.2 g or 3.8 knot/s) is shown. The go-around speeds and elapsed times as a function of touchdown/lift-off speeds and the actual touchdown (air-) distance from the runway threshold are shown for a 5,500 foot runway.


VLOF [knots]Air-Distance (Touchdown)

1,500 ft 2,500 ft 3, 500 ft

120106.5 kts 111.2 kts 115.7 kts

14 s 9.2 s 4.5 s

130117.6 kts 121.9 kts 126.0 kts

13 s 8.4 s 4.2 s

140128.6 kts 132.5 kts 136.3 kts

11.9 s 7.8 s 3.9 s

Table 2: The calculated go-around (aborted landing roll) groundspeed and the maximum safe elapsed time before go-around is initiated with a 1,000 foot “indecision” distance, hydroplaning surface and no thrust reversers deployed (0.05 g or 0.96 knot/s) is shown. The go-around speeds and elapsed times as a function of touchdown/lift-off speeds and the actual touchdown (air-) distance from the runway threshold are shown for a 5,500 foot runway.




Problems with rejected landing go-around:

• Change of pilot’s attitude from STOP-STOP to GO-GO takes time (inertia), discipline, and proper training.• Potentially this is more dangerous than v1-cut (action speed).• Inertia in airplane dynamics and also in human decision making takes time and shrinks the safety margin.• Complexity of the calculations/decisions.• Generally, better to exit runway at slow(er) speed than risk stalling in and/or hitting obstacles on the initial climb.


CONCLUSIONS

Precise airspeed, height, and touchdown control is essential in daily airplane operations and especially so on contaminated runways and/or during LAHSO operations.

Combination of slippery (contaminated) runway surface combined with X-wind can easily lead to veer-off accident.

A PNR exists on the runway based on the TOGA-action speed. This is the lowest speed that the airplane can slow0down to before initiating GA and acceleration for takeoff. This speed will depend on many factors such as LDA, deceleration and acceleration magnitude, touchdown point and speed, wind, etc.

An electronic /AVIONIC system can be devised and incorporated in PFD/MFD (or HUD/HGS) with aural warnings that could give pilots information about the location of PNR, go-around action speed, the probability of successful TOGA and acceleration levels.


"Una volta che hai gustato il volo, camminerai sulla terra con gli occhirivolti sempre in alto, perché là sei stato, e là agogni a tornare“

"Once you experience flight, you will walk on the earth with your eyes looking up to the sky, because there you have been, and there

you wish to go back“. (Leonardo da Vinci (1452-1519))

THANK YOU!

Questions?


Documents

Regional Airline Operations on Contaminated Runways · on Contaminated Runways ... for landing on slippery runway with and ... condition (wet, contaminated), engine failure in attempted