2. Landing Overruns - Human Factors
A review of the events leading to, and lessons
learnt from the over-run of flight QF1 at Bangkok
Thailand, September 23, 1999.
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Qantas Airways Limited
3. Landing Configuration
• Operating Boeing 747-400 since 1989
• Standard landing configuration up until 1996
was “Flap 30, Full Reverse Thrust”
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Qantas Airways Limited
4. Landing Configuration
(continued)
• Review of landing configuration was
undertaken due to:
– Noise levy at Sydney
Flap 25 chosen for lower noise,
better fuel economy
– Carbon Brake Wear
Idle reverse thrust chosen for
less noise and longer, harder
brake application
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Qantas Airways Limited
5. Landing Configuration
(continued)
• Landing configuration Policy from late 1996 was:
– Flap 25, idle reverse thrust provided the
runway length was not limiting
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Qantas Airways Limited
6. The Landing
• F/O was pilot flying
• The runway was wet
– The last landing airplane had reported
“good” braking action
– The airplane preceding QF1 executed a
Missed Approach due to poor visibility in
heavy rain
– This was not relayed to the crew of QF1
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Qantas Airways Limited
7. The Landing
(continued)
• Airplane crossed the threshold high and fast
(but within Company limits) and “floated” 10ft
above the runway in heavy rain
• Within a period of just a few seconds:
– The Captain called for “Go- Around”
– The main gear touched down
– The rain eased and visibility improved
– Captain reached over and took control of
the thrust levers
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Qantas Airways Limited
8. The Landing
(continued)
• The Captain initially only retarded # 2, 3 and
4 Thrust Levers
• The F/O immediately realized this and retarded
#1 to idle, however:
– With main gear on the ground and # 1 or
4 T/L advanced, the autobrakes disarmed
– Speedbrakes deployed automatically after
#1 T/L was retarded by the F/O
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Qantas Airways Limited
9. The Landing
(continued)
• The EICAS message “AUTOBRAKES” was not
initially noticed by the Flight Crew
• Manual braking was not applied until 8 seconds
after touchdown, approx 5000 feet down
the runway
• No reverse thrust was applied for the whole
of the landing roll
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Qantas Airways Limited
10. The Landing
(continued)
• When manual braking was applied
NO deceleration was felt
• Both pilots exerted maximum force on the
brake pedals, still with no deceleration
– The airplane was aquaplaning
• The airplane only began to decelerate as it
entered the last 1000 feet of the runway and
the groundspeed reduced below 110kts
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Qantas Airways Limited
11. Acft drifting left Nose gear squat Nose gear
SPLR deployed
of rw y C/L sw itch air mode departs sw y
CAS 160 kts
CAS 158kts Acft returning
CAS 143kts CAS 88kts
GS 158 kts
Touchdow n GS 156kts to rw y C/L
GS 141kts GS 87kts
Air-gnd logic CAS 107kts
Manual Nose gear Nose gear squat Acft on rw y C/L
to gnd mode SPLR start deploy GS 106kts
braking touchdow n sw itch gnd mode at threshold
CAS 156 kts CAS 160 kts
indications CAS 146kts CAS 139kts CAS 96kts
GS 158 kts GS 158 kts
V S
CAS 154kts GS 145kts GS 138kts GS 92kts
W
GS 1 2k
DECELERATION
ft /sec2
-7.00
Acft accelerating Aerodynamic Aerodynamic
due to braking and
-6.00
residual thrust only w heel braking
-5.00
-4.00
-3.00
-2.00
-1.00
3287ft 4000f 5000ft 6000ft 7000ft 8000ft 9000ft 10000ft
1002m t 1524m 1829m 2134m 2438m 2743m 3048m
Decelerat ion at main gear posit ion
Distance from Rwy 21L displaced threshold
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Qantas Airways Limited
12. Comparison of rollout deceleration on various runway surfaces and VH-OJH 23 September 1999
-14
Dry runw ay
* Mu 0.35 - 0.41
-12
-10
Wet runw ay
* Mu 0.20
-8 * Good braking action
Deceleration (ft/sec2)
-6 Flooded runw ay
* Mu 0.05
* Poor braking action
-4
Manual braking Aircraft on Aircraft
indications 5002ft to rw y centreline at nosegear
Aircraft passing Aircraft
Aircraft passing over 2015ft to
-2 end start of sw y departs end
over rw y mkgs and returning to rw y
rw y mkgs and abeam rw y end
of sw y
approaching tw y S centreline 770ft
Aircraft drifting left of tw y W 2536ft to rw y
1100ft to rw y end to rw y end
centreline 5522ft to rw y end
0 Autobrakes
end
disarmed
2
Spoilers deploy
4
160 150 140 130 120 110 100 90 80
Acf tconfig for various runw ay surfaces:
Ambient conditions: Groundspeed (knots) * 252,000 kg Vref25 + 5 kts
OAT 25 deg C
* Maximum manual braking
QNH 1013.2 23 Sep BKK Dry Rwy Contam Rwy (Good brkg) Contam Rwy (Poor brkg)
* Spoilers deployed, Idle forw ard thrust
WIND 3.6 kt HWC
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Qantas Airways Limited
13. Human Factors
• Why did this happen ?
• Accident analysis showed:
– A number of significant active failures and
– Significant inadequate defences
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Qantas Airways Limited
14. Active Failures
• The runway was affected by water
• Flight Crew failed to use an appropriate risk
management strategy for the approach
and landing
• The F/O did not fly the aircraft accurately
during final approach
• The Flight Crew were confused over who had
control and did not select appropriate level of
reverse thrust
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Qantas Airways Limited
15. Inadequate Defences
• Company published information, procedures and
training for landing on water affected runways
was inadequate
• Flight Crew training in evaluating the procedural
and configuration options for approach and
landing was deficient
– The crew may have been “pre-conditioned” to
the use of Flap 25 and idle reverse thrust
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Qantas Airways Limited
16. Change Management
• Published the Boeing document “Landing
on Slippery Runways” (doc D6-44247) in
the Qantas Flying Manual
• Provided a flow chart to assist Flight Crew
in determining appropriate flap and reverse
thrust settings
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Qantas Airways Limited
17. Aircraft Weight
Environmental Conditions
Evaluate Runway
Conditions as Reported
Runway Contaminated
Runway Dry Runway Wet
or Slippery
Reported
Determine F25 Landing
Braking Action
Field Length
Is F25 Landing Field
GOOD MEDIUM POOR
Length less than
No
Available Distance?
Yes
Determine F30 Landing Field Length Do not land unless a greater
Use Flap 25 and Full
emergency exists. Hold until
Reverse Thrust
conditions improve or divert
Determine F30
Landing Field Length
Is F30 Landing Field
Is F30 Landing Field Length less
Length less than
than Available Distance?
Available Distance?
No Yes
Yes No
Use Flap 30 and Full Use Flap 30 and Full
Use another Runway
Reverse Thrust Reverse Thrust
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Qantas Airways Limited
18. Change Management
(continued)
• Flight Crew use max reverse thrust as the
“standard” with idle reverse permitted only
under stipulated conditions
• Flap 25 is the normal landing flap on
dry runways
• Flap 30 used on wet runways (no credit taken
for grooving or PFC overlay)
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Qantas Airways Limited
19. Change Management
(continued)
• Produced CBT package summarising
performance on slippery and contaminated
runways
• Provided detailed stopping distance information
for various surface conditions
• Highlighted to crew the importance of using
correct techniques for landing on wet, slippery
and contaminated runways
• Included call of “AUTOBRAKES” each time
this is annunciated on EICAS
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Qantas Airways Limited
20. Change Management
(continued)
• Monitoring of landing configurations and
touchdown points has shown:
– Significant trend towards flap 30 irrespective
of runway conditions
– Max. reverse thrust used on most occasions
– Touchdown points are closer to the “desired”
point. i.e. less “float”
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Qantas Airways Limited
24. Cabin Communications
• Nose gear collapse resulted in loss of all Flight
Deck / Cabin communications
• Confusion existed as to need for evacuation
• Co-location of back-up comms equipment in an
area prone to damage is considered undesirable
• Provided Flight and Cabin Crew with procedures
to use in the event of loss of Cabin Interphone
or PA
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Qantas Airways Limited
25. Summary
• Provide Flight Crew with the appropriate tools
to do the job
• Train Flight Crew to analyse each landing
separately to determine the appropriate landing
configuration
• Ensure procedures for landing on wet, slippery
and contaminated runways are in place and
thoroughly understood
• ATSB report available at www.atsb.gov.au
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Qantas Airways Limited
