Southwest B737 Overrun @ Chcago MDW

[canyonblue737]

Originally Posted by jondc9

To CANYON BLUE:
You indicated that the auto spoilers deployed on landing and the auto brakes worked too.
How do you know?

intial NTSB press statements from FDR data revealed it. spoilers did deploy and autobrakes worked as designed. as for why the TRs didn't deploy i have no idea and no comment.

[Tanker]

Originally Posted by potuspilot

2 engine jets still have one engine left if one fails. Using reverse thrust credit in this case is like flying over water in a single engine. If it fails you go down.

I'm not disagreeing with you. I was just pointing out that since engines are now more reliable that is why we have 2 engine ETOPs. Boeing must have used the same reliability logic to get the FAA to approve thrust reversers included in the landing data. IMO the logic is flawed, but is th only reason I and some of my co-workers can understand why it occurred.

[jondc9]

while the ntsb did say that autobrakes started to work and the PILOTS disengaged and went to manual braking I have seen NOTHING regarding the spoilers. If you have it, please post.

The captain has stated he went to manual braking because he didn't feel deceleration.

I spoke to the NTSB PR MAN and asked about the spoilers and they had no comment on that.

If I am wrong, please post NTSB DATA and I will appologize.

I will ask this question in the nicest way possible. Would southwest airlines have been the launch customer and / or made any purchase of the 737-700 series if reversers were not part of the stopping equation? That is, would a major redesign of the 737-700 have had to be made if it couldn't operate at MDW?

I once spoke to a guy hawking the BAE ATP (everyone remmber that plane?)

OUR little airline flew to TVL (south tahoe airport in california, KTVL for you across the pond). I asked if the BAE ATP could handle TVL on a hot day. the some 50-60 passenger plane could...but only with 2 passengers and NO luggage!!!!! The sales rep from BAE said, "well, you just won't go to TVL in this ".

Our airline didn't end up buying any BAE ATP's.

I wish I had the smoking gun on the -700...but until then I will just wonder...things that make you go, "hmmmmmm".


j

[tribo]

I guess this link would be of interest for this tread:
http://www.pprune.org/forums/showpos...3&postcount=43
Follow the links, open the document and make a search on any topic you want.
For this tread following keywords should be relevant: Southwest, Midway, thrust reverse, contaminated, +++++
You might learn something from the rulemaking process that could be useful

[GregMagicQuist]

All,

The 67% runway left discussions refer to PREFLIGHT, dispatch planning only. Upon arrival, you can "plan" to use ALL the runway if needed under the conditions, even if maximum stopping performance is required to have one foot left. (Not smart, perhaps, but legal). One "should" have some solid margin left upon arrival, though, BECAUSE OF that preflight planning requirement; which is the whole point of the preflight planning FAR with tons of "slop".

Approach end displaced threshold is NOT considered in landing distance math. TCH's are, therefore, AT the "threshold" where green lights and paint are. Displaced thresholds on the approach end are included for takeoff calculations only. Departure end displaced thresholds do "count" for landing and takeoff abort distances.

SWA OPC calculations assume ALL landings touch down 1500 feet from the "threshold" (not displaced threshold where takeoff roll starts). Following the HUD AIII mode WILL put you down 1500-2000 feet from "that" threshold unless "flare guidance" is ignored once visual. Hence, a 1000 foot additional margin is added to landing distance if "AIII" is selected for a real AIII low vis approaches with our 50 ft decision height. AIII published approaches only exist on long runways, so following flare cues in 700 ft RVR's is not a problem. It IS a problem at MDW. 31C ILS-Z is NOT an "AIII HUD" approach, but an "IMC HUD" approach (GS info goes away with no precision flare guidance at 35 ft). ILS-Z HUD only means IMC HUD (NOT "HUD AIII") and the new Jepps changes on the approach plate specifically disallow using the AIII approach. Heck, it is a CAT I approach requiring 3000 RVR! The special HUD use simply lowered the normal ILS DH from 250 ft AGL to 200 ft AGL in order to pick up the LDIN and threshold lites earlier.

It is EASY, and IMO, proper to "retarget" to the 500 ft point under such conditions using the HUD if one "had" to land at MDW for whatever reason (emergency, fire, etc). That gives one 1000 ft more stopping margin than OPC predicts!! Once visual at minimums, ease the HUD flight path marker (i.e. ground impact point!) onto the "real" threshold lites and drive in holding it there (on speed, of course) until the flare point at about 30 feet. If you do the trigonometry you get a 4.06 degree glideslope from 200 ft "on" the normal 3 degree glideslope (I.E. at normal DH) to the threshold (instead of to abeam the GS antenna at about 1000 ft from the threshold). There are no approach lites to "hit" anyway with the displaced thresholds. A 3 second or so flare "process" then makes you "miss" the threshold "impact point" and you safely touchdown around 500 ft down from it (with about a 20 ft TCH... no problem). IMO, this is perfectly safe, prudent, and legal by FAR's. It is “stabilized” also at just under 1000 fpm sink rate for average weights.

It is not SWA "SOP" to NEVER, EVER "duck under" or “retarget“ in any STRICTLY written verbiage (although it is in many pilot‘s minds). IMO, short, slick, runways make shortened “aim points” the SMART thing to do and there is wiggle room in "SOP" verbiage to do so (not to mention FAR's blatantly allowing it... see below). There is NOT an industry “land short problem”… there IS an industry “overrun” problem. If a 737 captain can't safely touchdown at the 500 foot point easily at any time you might need to -- IMO, that is problematic.

The regs allow a thinking pilot to do what is necessary after DH/MM glideslope-wise to ENSURE a safe landing. SWA removed (for unknown reasons... good, IMO) the short-lived 2004 revision language which stated we “fly the glideslope to the flare“ well before this accident. Here is the Reg:

FAR Part 91.129.e
“(2) A large or turbine-powered airplane approaching to land on a runway served by an instrument landing system (ILS), if the airplane is ILS equipped, shall fly that airplane at an altitude at or above the glide slope between the outer marker (or point of interception of glide slope, if compliance with the applicable distance from cloud criteria requires interception closer in) and the middle marker; and
(3) An airplane approaching to land on a runway served by a visual approach slope indicator shall maintain an altitude at or above the glide slope until a lower altitude is necessary for a safe landing.”

Respectfully,
GQ

[jondc9]

IF I were head of the FAA:


I would no longer allow "tail wind" operations at MDW. Its that simple. There are a few more airports in the country that would also take this hit, but its that simple.

Marginal airports for transport jets must have a number of safety factors :

All jets going into MDW would have to have operational thrust reversers if so equipped (the BAE 146 doesn't have thrust reverse but would be a great midway plane). Thrust reverse shall never be credited in landing distance.

MDW must have emas systems at the end of all runways used by transport jets.

MDW should have better approach lighting systems.

All "special" instrument approaches will hereby be cancelled.

MDW shall have better runway remaining alerting systems.

MDW airport shall have seperate and special alternate requirements and special holding fuel requirements. While alternate plus 45 minutes is OK for most airports, MDW shall have alternate plus 90.


j

[jondc9]

Mike

yes, caught between the devil and deep blue sea is right. But consider, pax want to go to Chicago, best damn alternate to MDW is ORD. BUT just try to get in line at ORD during a snow storm.

And to those who know Chicagoland, we must also wonder why the Mayor ordered bull dozers in to chop up and destroy MEIGS field and not Midway. If his logic had been used, Midway would be gone too. But $$$$ speaks louder than words.

Chicago is a great city. I love it! Its a todd'ln town. But if its going to have MIDWAY airport they should do it right and not half assed.

I recall how much they spent on the terminal to make it better, more modern and how little they did for the airport itself.

When I started flying to Midway in jets, the terminal looked just like it did in the movie "North by Northwest" (though with jetways).


j

[tribo]

Runway Surface Condition - Braking Action

From - Southwest Airlines Runway Surface Condition Survey
November 1999 - May 2000 - I find that Southwest use the scale:

• Dry
• Wet-Good
• Wet-Fair
• Wet-Poor
• 0.25" clutter
• 0.50" clutter

The terms Wet-Fair and Wet-Poor where used the day of the accident.
In NTSB SIR-83-02 - Large Airplane Operations on Contaminated Runways, May 3-5, 1983, the 1980 edition of the Air Transport Association's Snow Removal Handbook describes Pilot terms for their members as follows:

GOOD - More braking is available than will be used in an average airline type deceleration. If a max energy stop were attempted, some distance in excess of certified stopping distance would be expected.
FAIR - Sufficient braking and cornering force is available for a well flown approach and landing using light braking. However, excess speed or long touchdown would result in an extremely low safety factor depending on runway length and crosswind component. Careful planning and good judgement are required.
POOR - Very careful planning, judgement and execution are absolutely essential. Crosswind becomes a "priority one" consideration. While a safe and successful approach, landing and stop can be accomplished if all factors are favorable, there is little room for error. Care must be exercised in every facet of the operation and a very careful evaluation of all existing conditions is necessary.
NIL - Extremely slippery with poor directional control even while taxiing. This is the kind of report we would envision during a freezing rain condition if nothing were done to the runways or taxiways.

Is there any description to the scale used by Southwest?
How does these scales relate to eachother?

[tribo]

Thanks Bonger

Information from the NTSB letter to FAA dated January 27:

Snow began to fall in the area surrounding MDW about 5 hours before the accident. While the flight was en route and holding to land at MDW, the flight crew obtained updated weather information and runway braking action reports from air traffic control. On the basis of this information, the flight crew planned for fair braking action on landing on runway 31C. The runway was last cleared and treated about 45 minutes before the accident. About 30 minutes before the accident, airport ground personnel performed a runway friction measurement, which indicated that the runway friction was "good". About 1/8 to 1/4 inch of scattered snow was on the runway when the airplane touched down.

Under such circumstanses, would it not be more correct to use contaminated performance data THIN CLUTTER in stead of wet performance data WET-FAIR?

[tribo]

Potuspilot

I was refering to the info in the NTSB letter - not what was actually passed on to the crew.
Thanks for the clarification of SCATTERED vs. THIN CLUTTER.
One could not read that from the scale as SCATTERED was not defined there.
Is there another scale including SCATTERED in existance?
Are there any guidance material related to the scale?

[jondc9]

Perhap it is time to realize that all aviation enterprise must have safety backup in depth.

When a naval aviator attempts a landing on a carrier, he shoves throttle forward at touchdown just in case his hook misses the wire.

A backup plan must always exist. At MDW, there was no backup plan except perfection.

In depth safety:

1. EMAS overrun.

2. Emergency thrust reverser memory item checklist

3. higher approach minimums.

4. prohibition on tailwind operations.

5. Higher requirements for runway needed at MDW...instead of the 60percent rule, make it better at 50%.


While any airplane can over run any runway, MDW (lga, isp, sfo) all seem to need a bit more margin.

regards

jon

[RatherBeFlying]

Where to put the EMAS

One press article mentioned that MDW had no room for EMAS and I can see that subtracting a few hundred feet from an already constrained runway has consequences on loadings and revenues.
So here's what to do:

1. Convert the roads at the ends of 13-31C to underpasses
2. Put EMAS on top

[barit1]

At the NW end, to gain more than a few hundred feet, you'd have to bury the rail lines too. Huge infrastructure cost.

How about some ATC refinements so that downwind landings aren't forced on the traveling public? Should be a whole lot cheaper & more efficient.

[jondc9]

<<<How about some ATC refinements so that downwind landings aren't forced on the traveling public?>>>


How about every pilot going to midway advises chicago center prior to handoff to approach control that they will not accept a downwind operation?

PILOTS its up to you, if you are still the commanders of your aircraft.

jon

[tribo]

Bonger
Thanks for the info with respect to the operational use of the THIN CLUTTER and 0.50 IN CLUTTER terms.
This info leads to the question:
How to make corrections for landing at a RWY contaminated with snow and ice (more than 25%)?
The description of the terms WET-GOOD, WET-FAIR and WET-POOR relates to wet runways.

Note: “WET” runway conditions cover distances for braking actions only.

[safetypee]

tribo your question is at the centre of this accident and of many similar incidents.
There are industry wide problems with communication, assumption, and lack of knowledge.
Will the FAA’s failure to conform to ICAO Annex 14 be a contributory factor, or is it the general lack of standardisation for runway condition terminology involved? See Good - Fair - Poor – Nil and Braking Action Table.
There appears to be a similar disparity in terminology between ATC, Operator, Dispatch, and Manufacturer (OPC), thus it should not be surprising that there are opportunities for error. In addition there are major issues relating to the accuracy of the runway friction measurement.
There appears to be a lack of knowledge as to what exactly is used to determine landing distance on contaminated runways and what safety margins exist or are required.
Historically the FAA has progressed from dry runways to factored wet, and now recommends an allowance for contaminated. JAA require measured or calculated contaminated data, but the safety margins may not be any better than for wet runways (JAR-OPS 1.520).
The Canadians have identified that a margin of 2.2 or 2.4 might be required to maintain an equivalent level of safety as opposed to the current 1.97 wet factor. Aircraft Braking Performance on Wet Concrete Runway Surfaces and also see Benefit-Cost Analysis of Procedures for Accounting for Runway Friction on Landing. The latter PDF document includes the CRFI table and discusses risk and risk assessment (section 4), this is a ‘must read’ for all pilots.
Both the authorities and manufacturers place great responsibility on operators for interpreting the guidelines on landing distance.

Boeing
- If runway is reported to have slush/standing water covering, the flight crew should be suspicious of braking action reports and measured friction
- For landing, Boeing recommends the use of the data labeled ‘poor’ for slush/standing water due to the possibility of hydroplaning
- If runway conditions warrant, review the performance data to ensure the runway length exceeds the expected stopping distance by an adequate margin

There are also many human factors issues. The pilot is normally considered the last point of defense after all other defenses have failed, but for overruns there appears to be very few active defenses upstream of the pilot; it appears that the management of these or opportunity to implement them has already failed.
How to make corrections for landing at a RWY contaminated with snow and ice (more than 25%)?
For contamination with wet/slush/risk of aquaplaning, pilots should be balancing their choice of options on at least a safety factor of 2, i.e. double the sum of a ‘sporty’ 1000ft airborne distance from 50ft (landing at the correct speed), plus the published ground roll distance for the conditons. In addition there should be no tailwind or credit for reverse.

[tribo]

Safetypee et al

There are industry wide problems with communication, assumption, and lack of knowledge.

There appears to be a similar disparity in terminology between ATC, Operator, Dispatch, and Manufacturer (OPC)

the general lack of standardisation for runway condition terminology

I know the treads referred to (I started them) and I know the reports.
Please do not forget the ground staff who actually are the persons who identify the significant changes and report the conditions at the movement area.
I belive we all need to speak the same language and we should focus on that. There should be a standardised set of runway condition terminology across State borders used by:

• Manufacturer - documentation
• Authorities - sertification and operation
• Airport operators - identifying significant changes and report them - (Main focus on getting rid of the snow and ice and then report)
• Aircraft operators - SOPs

How can we achieve this?
ICAO is not "up to date" on the subject.
Who sets the agenda? (EASA? - GASR? http://www.airports.unina.it/home_eng.html)
(The Canadians and the Europeans (EASA) do make corrections for RWYs covered with more than 25% of snow and ice)

[tribo]

NTSB hearing and FAA announcement (Federal Register)

NTSB hearing at this link:
http://www.ntsb.gov/Events/hearing_sched.htm
FAA document at this link:
http://frwebgate.access.gpo.gov/cgi-...WAISmaxHits=40

[vapilot2004]

CVR Transcript - AC Perf findings - RWY Friction Logs

Direct access links to CVR Transcript:
CVR

Runway Friction Testing Log:

Link

Aircraft Performance:
Link

All released documents from NTSB on this:
Complete Exhibit List

[jondc9]

Dear VApilot

Thank you for posting this information. I am on the mailing list for NTSB and still haven't gotten it that way.


My fellow aviators. I've read the CVR transcript. It is quite long, but every word gives insight.

(no jokes danny) I will refrain at this time from giving my views, as I would like to read this a number of times...I may even print it out and write notes on the side.


This is a rare opportunity to really get in the cockpit with this crew.

regards

jon