Tui runway excursion at Leeds Bradford 20/10/23
“ The problem with heavy rain at Leeds, is that even if you can land comfortably in the 115% Factored LD, the technique for recovery from loss of directional control creates a huge decision problem: “
Not judging here but :
Part of the FAA SAFO 19003 States :-
Subject: Turbojet Braking Performance on Wet Runways.
Purpose: This SAFO cancels and replaces SAFO 15009 and warns airplane operators and pilots that the
advisory data for wet runway landings may not provide a safe stopping margin especially in conditions of
Moderate or Heavy Rain.
Background: Landing overruns that occur on wet runways typically involve multiple contributing factors
such as long touchdown, improper use of deceleration devices, tailwind and less available friction than
expected. Several recent runway-landing incidents/accidents have raised concerns with wet runway
stopping performance assumptions. Analysis of the stopping data from these incidents/accidents indicates
the braking coefficient of friction in each case was significantly lower than expected for a wet runway as
defined by Title 14 of the Code of Federal Regulations (14 CFR) part 25 § Section 25.109 and Advisory
Circular (AC) 25-7D methods.
These incidents/accidents occurred on both grooved and un-grooved runways. The data indicates that
applying a 15% safety margin to wet runway time-of-arrival advisory data, as recommended by
SAFO 19001 (or current guidance), may be inadequate in certain wet runway conditions. Takeoff and
Landing Performance Assessment (TALPA) procedures implemented by the FAA on October 1, 2016,
added new insight as to how flightcrews can evaluate runway braking performance prior to landing.
TALPA defines WET as “Includes damp and 1/8-inch depth or less of water,” while CONTAMINATED is
“greater than 1/8-inch of water.
”
Discussion: These overruns have occurred on grooved and smooth runways during periods of moderate to
heavy rain. Analysis of these incidents/accidents indicates that the braking coefficient of friction in each
case was significantly lower than expected, and that 30 to 40 percent of additional stopping distance may
be required if the runway transitions from wet to contaminated based on the rainfall intensity or reported
water contamination (greater than 1/8-inch depth). For the operational in-flight landing assessment,
determining whether the runway is wet or potentially contaminated is the pilot’s responsibility.
The FAA recommends that airports report “Wet” conditions. However, airports are not required to report
when a runway is only wet. Further, an airport may not be able to generate a Field Condition NOTAM
(FICON) for sudden rain showers that result in water on the runway more than 1/8 of an inch in depth
(contaminated). Rainfall intensity may be the only indication available to the pilot that the water depth
present on the runway may be excessive. The 1/8-inch threshold that separates a wet runway with a
RWYCC of 5 from runway contaminated with water depth greater than 1/8-inch a RWYCC of 2 is based
on possibility of dynamic hydroplaning. This can be especially true in moderate rain if the runway is not
properly crowned, grooved, constructed with a porous friction course (PFC) overlay, or when water run-
off becomes overwhelmed. During heavy rain events, this may be true even on a properly maintained
grooved or PFC runway.
The TALPA RCAM recommends using landing performance data associated with medium to poor
braking or RwyCC of 2, if greater than 1/8-inch of water is anticipated to be on the runway. When
planning to land on a smooth runway under conditions of moderate or heavy rain, or when landing on a
grooved or PFC runway under heavy rain, pilots should consider that the surface may be contaminated
with water at depth greater than 1/8 inch and adjust their landing distance assessment accordingly.
Pilots should use all available resources to determine what condition they may expect upon landing to
include Air Traffic Control (ATC), FICONs (as some airports do report Wet conditions), flight
visibility, and/or onboard weather radar.
Not judging here but :
Part of the FAA SAFO 19003 States :-
Subject: Turbojet Braking Performance on Wet Runways.
Purpose: This SAFO cancels and replaces SAFO 15009 and warns airplane operators and pilots that the
advisory data for wet runway landings may not provide a safe stopping margin especially in conditions of
Moderate or Heavy Rain.
Background: Landing overruns that occur on wet runways typically involve multiple contributing factors
such as long touchdown, improper use of deceleration devices, tailwind and less available friction than
expected. Several recent runway-landing incidents/accidents have raised concerns with wet runway
stopping performance assumptions. Analysis of the stopping data from these incidents/accidents indicates
the braking coefficient of friction in each case was significantly lower than expected for a wet runway as
defined by Title 14 of the Code of Federal Regulations (14 CFR) part 25 § Section 25.109 and Advisory
Circular (AC) 25-7D methods.
These incidents/accidents occurred on both grooved and un-grooved runways. The data indicates that
applying a 15% safety margin to wet runway time-of-arrival advisory data, as recommended by
SAFO 19001 (or current guidance), may be inadequate in certain wet runway conditions. Takeoff and
Landing Performance Assessment (TALPA) procedures implemented by the FAA on October 1, 2016,
added new insight as to how flightcrews can evaluate runway braking performance prior to landing.
TALPA defines WET as “Includes damp and 1/8-inch depth or less of water,” while CONTAMINATED is
“greater than 1/8-inch of water.
”
Discussion: These overruns have occurred on grooved and smooth runways during periods of moderate to
heavy rain. Analysis of these incidents/accidents indicates that the braking coefficient of friction in each
case was significantly lower than expected, and that 30 to 40 percent of additional stopping distance may
be required if the runway transitions from wet to contaminated based on the rainfall intensity or reported
water contamination (greater than 1/8-inch depth). For the operational in-flight landing assessment,
determining whether the runway is wet or potentially contaminated is the pilot’s responsibility.
The FAA recommends that airports report “Wet” conditions. However, airports are not required to report
when a runway is only wet. Further, an airport may not be able to generate a Field Condition NOTAM
(FICON) for sudden rain showers that result in water on the runway more than 1/8 of an inch in depth
(contaminated). Rainfall intensity may be the only indication available to the pilot that the water depth
present on the runway may be excessive. The 1/8-inch threshold that separates a wet runway with a
RWYCC of 5 from runway contaminated with water depth greater than 1/8-inch a RWYCC of 2 is based
on possibility of dynamic hydroplaning. This can be especially true in moderate rain if the runway is not
properly crowned, grooved, constructed with a porous friction course (PFC) overlay, or when water run-
off becomes overwhelmed. During heavy rain events, this may be true even on a properly maintained
grooved or PFC runway.
The TALPA RCAM recommends using landing performance data associated with medium to poor
braking or RwyCC of 2, if greater than 1/8-inch of water is anticipated to be on the runway. When
planning to land on a smooth runway under conditions of moderate or heavy rain, or when landing on a
grooved or PFC runway under heavy rain, pilots should consider that the surface may be contaminated
with water at depth greater than 1/8 inch and adjust their landing distance assessment accordingly.
Pilots should use all available resources to determine what condition they may expect upon landing to
include Air Traffic Control (ATC), FICONs (as some airports do report Wet conditions), flight
visibility, and/or onboard weather radar.
Not the only city like that. When Bristol chose a site for its airport it picked Lulsgate Bottom, an airport developed during the war to teach instrument flying largely because of its poor weather record. By coincidence, or maybe not, it too had traffic lights (strictly speaking, more like level crossing light) on a road which passed close to one end of the runway back in the 70s for a good few years. I worked there for a while and remember that it could be a bit embarrassing is you forgot to let the traffic go wafter the aircraft had done its thing.
(Cloudy Town) Probably should have said that aloud a few times before locating the airport there.
I very much subscribe to the "there but for the grace of God, go I" theory. I feel for the crew, who as others have pointed out, hadn't started the day planning an excursion snd were just caught out.
However, i wonder if the "aft-loading" of the aeroplane may have been a factor, which worked against them.
If the CofG is deliberately aft (holds 3 & 4 fllled in an attempt to reduce cruise trim drag), does that reduce the nose wheels ability to counter the weather cocking tendency on the runway?
An aft CofG, an upslope on the runway (a feature of that runway at LBA) thereby further unweighting the nosewheel, the 737's very tall fin and rudder may have made the gusty conditions worse and hence reduce steering ability. And, with speed reducing, diminishing rudder/fin effectiveness the crew were not well placed.
Also, the 737's CofG can move aft for landing compared to takeoff under some fuel load combinations.
As far as I'm aware, Tui had such a policy (of aft loading) which, if still being followed, may have worked against their crew in this case.
Now, my fellow armchair experts, and Monday morning quartebacks, what say you?
However, i wonder if the "aft-loading" of the aeroplane may have been a factor, which worked against them.
If the CofG is deliberately aft (holds 3 & 4 fllled in an attempt to reduce cruise trim drag), does that reduce the nose wheels ability to counter the weather cocking tendency on the runway?
An aft CofG, an upslope on the runway (a feature of that runway at LBA) thereby further unweighting the nosewheel, the 737's very tall fin and rudder may have made the gusty conditions worse and hence reduce steering ability. And, with speed reducing, diminishing rudder/fin effectiveness the crew were not well placed.
Also, the 737's CofG can move aft for landing compared to takeoff under some fuel load combinations.
As far as I'm aware, Tui had such a policy (of aft loading) which, if still being followed, may have worked against their crew in this case.
Now, my fellow armchair experts, and Monday morning quartebacks, what say you?
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Seeing several comments about 115% LDR: The factor for wet runways for dispatch is 1.92, (FAA and EASA). Correct me if I am wrong, but the 1.15 factor is only for in-flight calculations, and emergencies, is it not ?
I don't have access to a Boeing landing distance calculator - is a wet Leeds runway with significant crosswind and a 1.92 factor long enough for a 738 dispatch ?
Perhaps with somewhere like Leeds, EGNM, where you have:-
Out of wind runway, leading to significant crosswinds, AND
Significantly humped runway surface, AND
Challenging turbulent wind conditions common on approach. AND
High, exposed position, subject to more common and more intense adverse weather conditions, AND
A non grooved runway surface,
........Then perhaps a factor larger than 1.15 should be mandated ? (Especially when the visibility is also close to the limits.)
I operated into Leeds in Bombardier Dash-8s, back in the day. Plenty of ALD for those smaller craft, but it was usually very erm........exciting, even so !!
I don't have access to a Boeing landing distance calculator - is a wet Leeds runway with significant crosswind and a 1.92 factor long enough for a 738 dispatch ?
Perhaps with somewhere like Leeds, EGNM, where you have:-
Out of wind runway, leading to significant crosswinds, AND
Significantly humped runway surface, AND
Challenging turbulent wind conditions common on approach. AND
High, exposed position, subject to more common and more intense adverse weather conditions, AND
A non grooved runway surface,
........Then perhaps a factor larger than 1.15 should be mandated ? (Especially when the visibility is also close to the limits.)
I operated into Leeds in Bombardier Dash-8s, back in the day. Plenty of ALD for those smaller craft, but it was usually very erm........exciting, even so !!
Seeing several comments about 115% LDR: The factor for wet runways for dispatch is 1.92, (FAA and EASA). Correct me if I am wrong, but the 1.15 factor is only for in-flight calculations, and emergencies, is it not ?
................................
A non grooved runway surface,
................
................................
A non grooved runway surface,
................
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I quite agree. My comment was in reply to Pug who was suggesting this was very similar to an incident involving a 747 at DSA where a 747 driver miscalculated doing a 180...
Whatever the cause was, I don't think it's the pilot trying to do a 180...
Whatever the cause was, I don't think it's the pilot trying to do a 180...
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My bad.
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However, i wonder if the "aft-loading" of the aeroplane may have been a factor, which worked against them.
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Seeing several comments about 115% LDR: The factor for wet runways for dispatch is 1.92, (FAA and EASA). Correct me if I am wrong, but the 1.15 factor is only for in-flight calculations, and emergencies, is it not ?
I don't have access to a Boeing landing distance calculator - is a wet Leeds runway with significant crosswind and a 1.92 factor long enough for a 738 dispatch ?
I don't have access to a Boeing landing distance calculator - is a wet Leeds runway with significant crosswind and a 1.92 factor long enough for a 738 dispatch ?
As has been mentioned, the condition of the runway may well have reported as wet, but with a higher level of contamination. The only requirement (as far as I'm aware of TUI's policies) is to make a MED/POOR calculation if heavy rain is reported. Consistent moderate rain that doesn't drain from the runway in sufficient time could reduce the BA I guess?
It's also worth mentioning Boeing's interpretation of crosswind limits - something along the lines of steady wind affects the limit but gusts only increase the workload. The NTSB's investigation of the B737-500 excursion of Continental at Denver should have dispelled that myth, but seems nothing has changed! I'll certainly keep this incident in mind now.
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Of course, the temptation is to add extra knots onto the VApp in windy, gusty crosswind conditions, but unless there is a headwind component, there shouldn't be any addition
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But they didn't overrun, they departed the edge. And I don't think it was deliberately done to aid stopping.