Chicago runway too slick at crash

[question everything]

Chicago runway too slick at crash

By Alan Levin, USA TODAY

The runway at Chicago's Midway International Airport was much slicker than pilots were led to believe on the snowy December night that a Southwest Airlines jet skidded through a fence and killed a 6-year-old boy, according to a USA TODAY analysis.

Runway 31C was so slippery that it would have been difficult for people to walk on, providing minimal traction for the jet's tires as pilots tried to slow down from a speed of about 150 mph, the analysis of investigative records found.

The accident on Dec. 8 raises national safety implications because it shows that the system of testing slick runways has potentially fatal flaws. Without accurate information about runway conditions, pilots can stumble into danger without warning. Officials at Midway have said conditions on the runway were "good" when Flight 1248 skidded into a roadway and struck a car, killing Joshua Woods. Other pilots who landed shortly before the accident reported that conditions on the runway ranged from "good" to "poor" in spots.

But the USA TODAY analysis, based on a physics formula using information released by the National Transportation Safety Board (NTSB), shows the conditions were "poor" at best. The computation uses the plane's speed and the distance it traveled on the ground. (Related: Pure runway physics)

(snip)


Find this article at:
http://www.usatoday.com/news/nation/2006-03-01-slick-runway_x.htm

[Kagemusha]

1. Determinations like this are exactly what the NTSB is for.

This makes sense and flaws in the testing of runway slickness is most certainly a serious issue that needs addressing in the future. It's as if it was CSI: Air Crash. Now something needs to be done about it.

[question everything]

2. Especially as many "experts" tended to blame the pilots then (nt)

[AngryAmish]

3. Ya think?

[Mithras61]

4. This is pretty much what I thought at the time of the accident...

My wife & I used to fly SWA a great deal. Neither of us had any bad experiences aside from the occasional landing that was a bit firmer than usual (almost like they thought the runway was 5 feet too high :)). I've found that most pilots can do pretty amazing things with those planes at landing, provided they get accurate info from the ground and tower.

[Wcross]

5. What caused the 18 second delay in the thrust reverse?

The plane would have stopped if the thrust reverse had been deployed earlier.

[Mithras61]

6. The plane woul.d have stopped if it had landed INTO the wind...

as well (est. from NTSB - 5,300 feet with the tailwind they had, about 1,000 feet less if they had landed into the wind - Dec. 15, 2005 - http://www.ntsb.gov/Pressrel/2005/051215.htm).

Pilot said in interview that he was unable to deploy thrust reversers. Co-pilot says he deployed them shortly after that with no problem. NTSB says tests to continue.

Other report http://www.southwestflight1248crash.com/news.htm]">here indicates a sensor problem that caused a delay in deploying the thrust reversers.

[Wcross]

7. Mechanical failure?

Why were they landing planes downwind with a slick runway? Still need more answers but its clear it wasn't the pilots fault.

[jljamison]

8. Instrument procedures

Midway has ILS capability in both directions on the runway in question:

Runway 31C at midway has the following minimums:
250 ft above ground level ceiling, 4000 ft runway visual range (3/4 mi visibility)

Runway 13C (opposite direction) has the following minimums:
250 ft above ground level ceiling, 5000 ft runway visual range (1 mi visibility)

The weather in effect at the time of landing was recorded 20 minutes before landing as winds 100 degrees
at 11 knots, visibility 1/2 mile in moderate snow/freezing fog, ceiling broken at 400 feet, overcast at 1400 feet, runway visual range 4500 feet.

While the winds were not favorable to runway 31 (30 degree quartering tailwind), the fact that the wind was offset by 30 degrees lessens the effect of the wind to less than 10 knots (I don't have my E6-B to calculate the actual tailwind component).

I suspect the reason 13C was not used is because of the runway visual range. It was reported as 4500 feet, but 13C requires 5000 minimum.

The pilots most likely also considered the fact that airplanes in front of them had landed ok, even with the runway condition and weather.

If the winds had been stronger, and thus requiring the use of 13C, perhaps they would have decided to hold or divert. Who knows.

As I recall, Southwest's procedures do not permit the inclusion of thrust reversers in the calculation of landing roll distance, so the possibility that they did not deploy in time or correctly unfortunately does not get them off the hook.

From a pilot's responsibility standpoint, they made the decision to accept the clearance for 31 given the conditions, they made the decision to go ahead with the landing, and they opted not to go around. Maybe 9 times out of 10 these guys put that plane down with no accident. Maybe 99 out of a 100. And maybe if the thrust reversers had deployed they would have stopped sooner & not killed that boy.

As with most airplane accidents, it isn't usually one thing that is cause and effect. Sure the runway was slick, but other planes had landed ok. Maybe there was a wind gust, but you have to combine these two facts with their decisions up to this point in accepting the clearance and attempting to land.
And I don't think the pilots would blame the thrust reversers either...