When Full Thrust Isn’t Enough – A Sobering Look at Delta Flight 191

NM_18DeltaCrash4

Only a massive reserve of excess thrust will get you out of severe wind shear — and sometimes that’s not enough. In writing my last article on wind shear and inertia, I was reminded of the chilling tale of Delta Airlines Flight 191.



Wreckage of Delta Flight 191, an L-1011Delta 191 was a landmark aviation accident that shook the industry. Flight 191 proceeded much like any other airline flight, right up until the last 40 seconds.

First Officer Rudy Price was at the controls with the assistance of Captain Ed Connors and Second Officer Nick Nassick. The first sign of trouble came at 800 feet AGL while on final approach into Dallas Fort Worth with a 24 knot increasing-performance wind shear.

The crew rightly anticipated a loss of performance and pushed the trust levers “way up” as the airspeed dropped from 173 knots to 133 – a 40 knot wind shear. Despite the L-1011′s nearly 160,000 pounds of thrust, the aircraft still slowed to 119 knots and rapidly descended to the ground where it bounced and skidded into water tanks killing 134 passengers and one nearby motorist.



Recording from the Cockpit Voice Recorder

 

Microburst diagramAfter the investigation, the NTSB concluded that Delta Flight 191 had entered a microburst. The probable cause faulted the crew for their decision to continue the approach into a cumulonimbus cloud with visible lightning and the airline for lack of specific training and procedures for avoiding and escaping low level wind shear. The NTSB also indicated the lack of real-time wind shear hazard information as another probable cause.

Despite the lack of training cited by the NTSB, this crew really did a great job. There isn’t much to wind shear escape other than applying max thrust and pitching for best climb. That’s probably going to be Vx for your aircraft unless the manufacturer or company training program specifies something else. The chilling truth about Delta Flight 191 is that sometimes you just don’t have enough power to get out of it – and that’s not a comforting thought. As with most weather-related issues, the best strategy is avoidance.


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About the author
Pat Flannigan is a professional pilot and aviation blogger. He has been flying for fifteen years and is currently working as an airline pilot in the United States.

16 Replies to When Full Thrust Isn’t Enough – A Sobering Look at Delta Flight 191

  1. Mohammad says:

    Very Sad day, still remeber that day. The L-1011 Will always live on. Long live the L-1011 Tristar. Best plane to hit the skies in aviation history, if it was another plane it would have just crashed right away, would have been down immediately.

  2. jdr567 says:

    I was in my car near the approach at that specific time. One of the things I remember is the sounds. There must have been 1000′s of emergency vehicle sirens going off all around me.
    Thanks for the audio.

  3. Victor says:

    I was working in Las Colinas at the time. I concur with jdr567′s comment (although “thousands” may be a tad hyperbolic). I recall seeing and hearing many emergency vehicles driving past on the highway. At the time, we didn’t know what it was all about — only that it was something major.

  4. Glen says:

    Delta 191

  5. R.D.Vanasse says:

    A similar event happened at JFK rnwy 22L with an EAL 727 flight from Msy.A following EAL 1011 felt the downdraft and initiated
    a missed approach procedure immediately and was able to recover.The captain said it touch and go and ver frightening.

  6. Paul says:

    The conclusion that wind shear avoidance is the best procedure requires common sense. You’re seeing streaks of lightning and rain shafts from a cell that lies directly ahead on your approach path and near a point at which altitude on GS will be low – you’re also seeing increasing performance confirming the presence of wind shear which will likely be doubled as decreasing performance at some point, closer and lower, and the conclusion is that the crew did all they could! Yes, after the fact they did but not before. Even with a lack of training, common sense dictates that you don’t keep going expecting things to improve, not when “dueling” with a TSTM on final approach even if the thrust to weight ratio is 1:1 or greater. Just as surely as gravity always wins when defied, such a duel will be won by mother nature almost every time when low and slow especially in a heavy where mass, inertia and aerodynamic drag will easily overcome the excess power available for climb as it did in this tragic case and others that followed.

    • While I don’t disagree with you that the crew shouldn’t find themselves in that situation, there’s just no way of knowing exactly what they were seeing on the radar and out the window. I’ve flown into some nasty looking stuff that turned out to be cake, and I’ve been humbled by some very tame looking rain showers on final approach that turned out to be a bad deal.

      I think you may be missing the point I was trying to make with this article, which is a follow up to my posts on inertia. I’m simply driving the point home that pilots should avoid severe windshear at all costs when possible because they could easily find themselves in a situation when a flawless recovery maneuver with enormous power and thrust might still be unrecoverable, as was this case for Delta 191.

      • Victor says:

        I guess we can’t know “exactly” what they were seeing, but we do know some details. Lightning was spotted directly ahead. Connors also apparently knew what was going on when the wind speed increased. He correctly forecast the drop in wind speed. So it seems clear he knew wind shear would be an issue. Shouldn’t that have been the time to abort? Also, there was traffic right behind them. Wouldn’t they have basically seen the same thing? Just ask them.

        As far as radar goes, I don’t think they had Doppler radar then, so they wouldn’t have seen that….

  7. Mike says:

    Intersting perspective and a very sobering photo

  8. Rob says:

    I was leaving work at Simuflite on the south side of the airport at the time, in brilliant sunshine, and was amazed by the stark contrast with a very dark weather formation to the north of the airfield. It was enough to make me stop and get off my motorbike to look. I can remember thinking I was glad not to be flying into the airport at the time. By the time I got home my wife and friend called me over to the tv, with breaking news about the crash. It must have happened just as I was leaving the airport boundary. I will always be amazed that ATC didn’t warn the pilots about the sharp weather front, because it was so obvious from the south side.

  9. Robert Chapin says:

    “Best climb” to escape wind shear is Vy. The Vx speed mentioned above requires more time in a given distance, which can be used to build altitude before clearing obstacles.

  10. Undeniably imagine that which you stated. Your favorite justification appeared to be at the internet the simplest factor to consider of. I say to you, I definitely get annoyed even as folks consider concerns that they just do not realize about. You managed to hit the nail upon the highest as well as outlined out the whole thing without having side-effects , folks can take a signal. Will likely be back to get more. Thank you

  11. emyrj2005 says:

    I agree that the L1011 was one of the safest aircraft ever to fly,but what I will never understand about this incident is why the Captain did’nt call TOGA as soon as they first encountered the downdraft and not a few (fatally late?) minutes later!

  12. website says:

    It looks to me that this website doesnt load up on a Motorola Droid. Are other folks getting the same problem? I enjoy this web site and dont want to have to skip it whenever Im away from my computer.

  13. David Webber says:

    take a look at the FAA’s Lessons Learned from Transport Airplane Accidents at lessonslearned.faa.gov Delta Flight 191 is one of the interactive modules and Eastern Flight 66 will soon join this extensive accident library. Lots of technical information as well as a study of cultural factors at the time of the accident.

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