Yesterday marked the 15th anniversary of the L’Express Flight 508 crash in Ensley, just west of downtown Birmingham. Bill Murray wrote an excellent piece here late last night on the disaster (scroll down to read it); The Captain and one passenger were the only survivors. The First Officer and twelve other passengers were killed in the crash, which was ruled as weather-related (the plane encountered severe wind shear on the approach to the Birmingham Airport).

On July 10, 1991 I was the chief meteorologist at Birmingham’s ABC affiliate at the time, WBRC-TV. We had just completed the 6:00 news on that summer evening, and instead of going home for dinner, I decided stay in the office and get some work done. First word of the crash shortly after 6:30, and my long time associate Bill Castle (who is now the chief photographer) somehow had a live truck at the scene within minutes of the crash, and had live pictures back to us by 6:45. We stayed live for a long time; I even recall Dan Satterfield (who was our morning meteorologist at the time; he is now chief meteorologist at WHNT-TV in Huntsville) bringing gas down to the live trucks so they would have an adequate supply of fuel for the night.

I happened to be recording our live radar at the time of the crash (which was during the 6:00 news), and I had to appear in court a few times during the ensuing litigation with that radar footage. It was pretty obvious to me that the plane went down because of the storm; it was not severe in the classic sense, just your typical thunderstorm on a summer afternoon in Alabama. But, even those kind of storms can produce a violent in vertical wind speed, and that was responsible for bringing the plane down. Convective wind shear is now taken very seriously, and hopefully won’t be responsible for any more tragic loss of life.

The Monday afternoon map discussion video is on the web, and available via iTunes:

http://www.jamesspann.com/

The radar is still fairly quiet as I write this at 2:00 p.m. Looks like most places will see a high somewhere between 88 and 92 today; that should be enough to get showers and storms going in scattered locations during the next five hours or so. Nope, it won't rain everywhere, but at least a few lawns will see a nice shower.

TOMORROW AND BEYOND: An upper air higb builds overhead during the rest of the week, which should mean increasing heat, and a decrase in the number of afternoon showers and storms. Looks for mid 90s Wednesday through Friday with only an outside risk of any one spot getting wet.

WEEKEND PEEK: The upper ridge will begin to shift west of Alabama over the weekend, which should mean an increase in afternoon showers and storms, especially by Sunday and Monday of next week.

LONG RANGE: Pretty routine weather is shown by the GFS for the rest of July, with rainfall and temperatures close to normal for ths time of the year.

TROPICS: Surface development is not likely in the disturbance north of Puerto Rico... and, we will continue to watch another wave in the Atlantic about 800 miles east of the Windward Islands. This wave continue to move streadily to the west, and might have some potential for development once it reaches the Caribbean in a few days.

ONE YEAR AGO TODAY: Hurricane Dennis slammed into the Florida panhandle east of Pansacola Beach, and a little west of Navarre Beach. The tropical action last year was almost non-stop through October after the arrival of Dennis.

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I will have the next map discussion video posted by 7:00 a.m. tomorrow...

The Monday morning map discussion video is available on the web, and on iTunes:

http://www.jamesspann.com/

Be sure and scroll down to read Bill Murray's story about the commuter jet crash in Ensley on this date in 1991... very interesting; I might share some thoughts about that event later today or tonight here on the blog.

THE ALABAMA WEATHER STORY: This is the time of year when weather changes are very slow in coming across the Deep South. The main day to day difference involves the frequency and placement of afternoon showers and storms. Model data today suggests precipitatable water values at Birmingham to be around 1.80" to 1.90", and 500 mb temps around -7 degrees (C) this afternoon. This should support afternoon showers or storms, but the rain won't fall everywhere. Hopefully you can catch a good shower today, because they should thin out for the rest of the week as warmer air aloft makes for a more stable atmosphere.

And, as the showers and storms thin out, heat levels will be rising. We should be in the mid 90s during the latter half of the week, and with higher dewpoints the heat won't exactly be comfortable. We will continue to mention the chance of a passing afternoon storm late this week, but they should be very widely scattered.

The upper ridge begins to shift to the west of Alabama late in the coming weekend and early next week, and that should mean a slow increase in the number of afternoon showers and storms.

TROPICAL WEATHER: We are watching the interesting wave about halfway between the Windward Islands and the coast of Africa... the wave is moving to the west with no signs of any development at this point. That seems to be the first real African wave of the season with some potential for survival. The system east of the Bahamas is a circulation aloft, and a surface based low is not expected.

LONG RANGE: Nothing really stands out on the 00Z GFS... the weather looks pretty typical here for the rest of July. Hot and humid, at least a chance of an afternoon storm on a daily basis.

I will have the next map discussion video posted by 3:30 this afternoon....

At 4:05 p.m. on July 10, 1991, L’Express flight 508 took off from New Orleans International Airport bound for Mobile. The eventual destination of the Beech C99 aircraft was Birmingham. It left Mobile at 5:05 p.m. with thirteen passengers, the Captain and First Officer. The Terminal Forecast for Birmingham indicated the possibility of thunderstorms, but the flight was uneventful. At 5:45 p.m., as the crew began its approach into the Birmingham area, the weather officer contacted the controllers at the airport and informed them that Level 3 and 4 thunderstorms extended from near the Vulcan VOR, a navigational aid west northwest of Birmingham to near Gadsden. The activity was pushing southeast. At 5:51 p.m., the pilot asked the controllers at Atlanta Center for permission to deviate around a thunderstorm buildup that was in their path.

At 5:55 p.m., a strong thunderstorm moved across the field at the Birmingham Airport. The tower made an announcement to all flights that a low level wind shear advisory was in effect. A Lear Jet on approach decided to cancel its approach and wait. At 6:00 p.m., the Atlanta Center handed off L’Express 508 to Birmingham approach control. The south radar controller acknowledged the plane and gave it permission to descend. At that time, a Piper Aerostar was on final approach to runway 5, using an instrument approach. At 6:01, the Lear asked controllers how the Piper’s inbound ride was going. The Aero reported no problems.

At 6:03, the BHM controller advised LEX 508 that the Lear had cancelled its approach. The Captain told the First Officer to advise the passengers that their landing might be delayed. At 6:05 p.m., the pilots of the Piper Aero reported that the ride had not been that bad during their landing. One minute later, the crew of LES 508 decided they would attempt the landing based on the report from the Piper. At 6:08, LEX 508 was advised to stay on the approach frequency in case they decided to abort. After replying “okay,” the Captain told the First Officer, who was handling the plane, to watch out for wind shear.

As passengers looked through the open cockpit door, through the windshield they could see the inky black sky of a thunderstorm directly in their path. They wondered aloud to each other if the crew was going to fly through the storm or go around it. In the cockpit, the Captain had given control of the aircraft momentarily to the First Officer so that he could consult a chart.

At 6:09, the transcript of the cockpit voice recorder tape indicated that the Captain told the First Officer that if he didn’t feel comfortable flying the plane during the landing to let him know. He also told him to look out for wind shear. Soon, the sound of very heavy rain can be heard hitting the windshield. Shortly thereafter, the BHM controller asked LEX 508 how the ride was. “Okay, so far,” was the response. Just before 6:11, Birmingham Approach told LEX 508 to contact the tower for landing. It would be the last radio transmission from the doomed flight.

On the ground in Ensley, several witnesses saw the plane as it flew over. They reported that very heavy rain, frequent lightning and winds strong enough to bed trees over to the grounds were occurring. One witness reported that the plane appeared to be struck by lightning. Several witnesses gave erratic reports about engine sounds. Seconds later, the Captain called for climb power. On the tape, the sound of the engines increasing can be heard. Suddenly, the plane lifted up and to the right. The Captain exclaimed, “What are you doing?” Then he realized that the upset was not due to anything the First Officer was doing. The plane then banked severely to the left, with the wings becoming nearly vertical.

On the morning of July 11, 1991, members of the National Transportation Safety Board were in Birmingham to investigate the crash of L’Express flight 508. The Beech C99 commuter aircraft had gone down on approach to Birmingham during a thunderstorm at approximately 6:12 p.m. CDT. The Captain and one passenger were the only survivors. The First Officer and twelve other passengers were killed in the crash. The investigators combined information from the cockpit voice recorder, interviews with the survivors and controllers and weather records.

The safety board expressed concerns about the Captain’s fatigue level, since he was flying the third of four flight legs scheduled for him that day. The fact that he had been on duty nearly fourteen hours led to concerns that he might have chosen to fly through the storm because he had been on duty so long. The investigators found that weather information was accurate and that the crew was properly informed about the storm. The fact that another plane had just landed through the storm concerned the investigators, because a similar sudden and violent unexpected motion like LEX508 experienced could have just as easily have happened to the first plane.

In the end, the NTSB decided that the probable cause of the L’Express crash was the decision of the Captain to initiate and continue an instrument approach into clearly identified thunderstorm activity, resulting in a loss of control of the aircraft from which the crew was unable to recover and subsequent collision with obstacles and terrain.

Thankfully, we have made tremendous progress in dealing with wind shear in aviation. I will keep that is mond as I board my flight to Tampa later Monday morning...