B737-Tailstrike

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B737-Tailstrike

 

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737.1
Tail Strike Briefing
Capt. Ray Craig
Airplane Validation & Flight Operations
Boeing Commercial Airplanes
May 2004
The Boeing Company 737.2
Planned Tail Strike
The Boeing Company 737.3
Planned Tail Strike
The Boeing Company 737.4
The Boeing Company 737.5
The Boeing Company 737.6
The Boeing Company 737.7
The Boeing Company 737.8
The Boeing Company 737.9
Presentation Overview
• General information
• Takeoff techniques
• Landing techniques
• Tail strike incidents on takeoff and landing
• Training recommendations
The Boeing Company 737.10
General Information
• More tail strikes occur on landing than on takeoff
• 82% of 737-400 tail strikes occurred on landings
• 737-400 does not have tail skid protection for
landing therefore has higher damage
• 70% of 737-800 tail strikes occurred on landings
• 737-800/900 tail skid does not protect the aircraft
body for landing. However, 737-800/900 have
adequate aft body landing clearance
• 1994-1995 was another tail strike peak period with
all Boeing models due to increased deliveries and/or
new pilots
The Boeing Company 737.11
Typical Takeoff Tail Clearance
Profile
The Boeing Company 737.12
Tail Strikes on 737-800
• 13 total tailstrikes to date
– 3 without damage (not listed)
– 10 with damage
– 3 occurred during takeoff
– 7 occurred during landing
– limited damage occurred during takeoff tailstrikes
– the 737-800/900 tailskid protects the aircraft on
takeoff not on landing
The Boeing Company 737.13
Takeoff Risk Factors
• Mis-trimmed stabilizer
• Improper rotation techniques
• Improper use of the flight director
• Rotation prior to Vr
• Excessive initial pitch attitude
• Heavy derate/flight control abuse during
gusty/crosswind conditions
The Boeing Company 737.14
Mis-trimmed Stablizer
• Usually results from using erroneous data
– Wrong weights
– Incorrect center of gravity (CG)
• Nose up mis-trim can present problems
– Normal recommended rotation rate is 2 to 3 dps
– Nose up mis-trim can rotate 5 dps or more
– Aircraft may try to fly off runway without any pilot
input
The Boeing Company 737.15
Improper Rotation Techniques
• Too early or too late rotation
• Too fast or too slow rotation
• Excessive rotation rate
• Excessive initial pitch attitude
• Rotation at incorrect Vr for the weight and flap
setting
The Boeing Company 737.16
Effects of Improper Rotation
• Slow or late rotation uses additional runway - lower
height at runway end
• Early, over or fast rotation - decreases initial climb
performance
• Early and/or fast rotation increases chance of tail
strike
The Boeing Company 737.17
Improper Use of the Flight Director
• Cannot rotate on the flight director
• Flight directors are designed to provide pitch
guidance only after the aircraft is airborne,
nominally passing 35 feet
• Proper rotation rate reaches 35 feet with about 15
degrees and a speed of V2 + 10 (V2 + 15 on some
models)
• An aggressive rotation into the pitch bar may rotate
the tail into the ground
The Boeing Company 737.18
Review of Proper Takeoff
Techniques
• Use normal takeoff rotation technique. Use same
technique for -600 thru -900
• Do not rotate early
• Do not rotate at an excessive rate or to an
excessive attitude
• Ensure takeoff V speeds are correct and adjusted
for actual thrust used
• Consider use of greater flap setting to provide
additional tail clearance
• Consider using Full Thrust during gusty/crosswind
conditions
The Boeing Company 737.19
Landing Risk Factors
• Unstabilized approach
• Holding airplane off the runway in the flare
• Mis-handling of crosswinds
• Over-rotation during go-around
Note: Tail strikes on landing generally cause more
damage. The tail may strike the runway before the main
gear damaging the aft pressure bulkhead.
The Boeing Company 737.20
Unstablized Approach
The Boeing Company 737.21
Unstablized Approach
• Usually appears in every landing tail strike
• Flight recorders show if not stabilized by 500 feet,
will never get the approach stabilized
– Excessive or insufficient airspeed in the flare
– Long on runway touch down
• Increases tendency towards large pitch and power
changes in the flare
The Boeing Company 737.22
Unstablized Approach … continued
• Spoilers add nose up pitching force when deployed
• Increases tendency toward vigorous nose up pull at
touch down causing a tail strike
• If the airplane is slow, pulling the nose up in the
flare does not reduce the sink rate, but may
increase it
• Throttles above idle at touchdown add to instability.
The Boeing Company 737.23
Holding Airplane Off Runway in the
Flare
• Allowing airspeed to decrease below Vref prior to landing
flare resulting in high pitch attitude
• Trimming the stabilizer nose up just prior to or during
landing flair
• Holding the airplane off with increasing pitch attitude in
an attempt to make an extremely smooth touchdown
• Touchdown with an increasing pitch attitude
• Failure to fly nose gear onto runway immediately after
main gear touchdown
The Boeing Company 737.24
Mis-handling of Crosswinds
• Crosswind landings may increase the tail strike risk,
especially in gusty conditions
• To stay on glide path at high ground speeds, descent
rates of 700 to 900 feet are required
• Cross controlling prior to touch down, reduces lift,
increases drag, and may increase rate of descent
• Combined effects of high closure rate, shifting winds
plus turbulence, can increase tail strikes
The Boeing Company 737.25
Over Rotation During Go-around
• Go-arounds initiated during flare and after a
bounced landing, can cause tail strikes
• If a touchdown far down the runway is likely,
consider a go-around
• Safe companies support go-arounds
The Boeing Company 737.26
Bounced Landing
• If a bounce occurs, hold or re-establish a normal
landing attitude and add thrust as necessary to
control rate of descent
• Thrust need not be added for a shallow bounce or
skip
• When a high, hard bounce occurs, initiate a goaround.
Apply go-around thrust and use normal goaround
procedures. A second touchdown may
occur during the go-around
FCTM Fllaarree aanndd Toouucchhddoownn
The Boeing Company 737.27
Review of Proper Landing
Techniques
• Maintain an airspeed of Vref + 5 kt minimum to start of
flare
• Airplane should be in trim at start of flare; do not trim in
the flare or after touchdown
• Do not “hold the airplane off” in an attempt to make an
excessively smooth landing
• Immediately after main landing gear touchdown, release
back pressure on control wheel and fly the nose wheel
onto the runway
– Do not allow pitch attitude to increase after
touchdown
– Do not attempt to use aero braking - it does not
work !
The Boeing Company 737.28
Training Recommendations
• Include tail strike awareness and prevention
briefings in all initial, transition and recurrent training
• Install and use simulator tail clearance page in all
simulators. This has proven to be a very effective
briefing tool during training
The Boeing Company 737.29
Continuous Training Awareness
• Emphasize DOs and DON’Ts of tail strike avoidance
during training
• Include video as a basic item in all crew retraining
sessions
• Include simulator software for tail strike awareness
• Display tail strike posters
• Distribute appropriate literature
The Boeing Company 737.30
Summary
• More tail strikes occur on landing than on takeoff
• Tail strikes are costly but can be prevented with
proper training
• Tail strike awareness and training should be
continuous
• Simulators can help
• Stabilize the approach by 500 feet AGL
The Boeing Company 737.31

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