B737-400 Autothrottle

[sbuyting]

Hi there,

I work for the television show "Air Crash Investigation" that airs on National Geographic channels around the world. We are producing an episode of our show on the 1989 British Midland 092 accident that occurred near Kegworth in the UK. We are trying to figure out a small technical detail that's not in the AAIB's Final Report.

In this BMA flight, just as they finished their climb, the crew experienced heavy buffeting (engine fan stall), crazy vibration, and they smelled smoke. Immediately, the Captain shut off the autopilot and took over controls, then asked the first officer which engine had the problems. When the first officer answered "the right one", the Captain told him to "Throttle it back." The report says the autothrottle also shut off, but we're not sure if throttling the right engine back would have resulted in the autothrottle automatically shutting off? Or would the crew have had to deselect the autothrottle separately before throttling the right engine back?

Can any of you Boeing experts shed some light on this for me? I'd appreciate your input.

Thank you.

[Stalker_]

Hi there, I am a bit of a fan of the show.

You might be Surprised to learn that the -400 is fitted with a sensor that automatically disconnects the auto-throttle if more than 10 degrees of separation is detected between the two thrust levers

I am surprised you would ask such a question on a forum with the amount of experts you have on the show

[sbuyting]

Hi Stalker,

Thanks for that info. We do have great experts we work with, but I'm on a bit of a deadline to get this answer, hence the reason I am here.

Much appreciated.

[ImbracableCrunk]

I'm not sure what the checklist was back then but now the first item on the drill is Autothrottle . . . .Disconnect.

[B737900er]

Im pretty sure Air crash investigation done an episode on the BMA crash??:confused:

I don't want to sound like a right :mad: but there is no mention of the 092 flight on the new series of Air crash.

[ImbracableCrunk]

Lessons Learned (http://lessonslearned.faa.gov/ll_main.cfm?TabID=1&LLID=62&LLTypeID=2)

The auto-throttle was disengaged in order for the first officer to manually reduce thrust on the right engine. Within two seconds of the thrust reduction on the right engine, the left engine fan speed stabilized at a level 3% below its previous stable value, and the EGT stabilized at about 50ºC above the previous stable value. However, the left engine fuel flow was still behaving erratically and continued to drop. The AVM continued to show a vibration value of five units. It was noted in the accident report that "the captain later stated that the action of closing the right engine throttle reduced the smell and the visual signs of smoke and that he remembered no continuation of the vibration after the right throttle was closed."

Not sure if the request is legit, but here's an answer. The FDR should have the info of when it was off, compare that to the TLA, and you should know whether it was via switch or TLA split.

[sbuyting]

Hi again,

@B737900er - No, ACI has never covered the Kegworth event. You must be thinking of Seconds From Disaster.

We're just starting work on Season 14, which means it won't air for at least another year and a bit.

@ImbracableCrunk - When you say the first item on the drill is to disconnect autothrottle, which current drill are you talking about?

[sbuyting]

Hi again @ImbracableCrunk

I just saw your other reply. We knew the autothrottle was disengaged, we're just not 100% sure on how it was done - whether it was automatic or switched off separately. It sounds like the answer might not as be black and white as I had hoped, so I think I'll wait until I interview the investigators next week for a definitive answer.

Thanks guys!

[ImbracableCrunk]

It seems from the FAA article that the A/T was disconnected via switch.

[sbuyting]

ImbracableCrunk - I totally read that wrong when I first looked at it. That FAA article does put it in pretty black and white terms. Thank you.

[Stalker_]

Just off topic slightly, it would be nice to see the reconstruction with an actual 737-400 cockpit.

So many of your episodes refer to a particular accident, but on the reconstruction the cockpit is not the same as that of the aircraft that was involved in the incident.

Also the same could be said for the cabin, e.g a 737 accident, but in the reconstruction you would have the cabin of a DC9 (3/2)

Just from a viewers point of view

[flyboyike]

I am surprised you would ask such a question on a forum with the amount of experts you have on the show


Thank you for the much-needed chuckle.

[Captaintcas]

Flyboymike,

Air Crash Investigation is a fantastic series, extremely professionaly done and we use it, together with " seconds from disaster" during our Safety and CRM courses as case studies.

[flyboyike]

Your point being?

[DozyWannabe]

Good luck with the show!

There are a lot of contributory factors to cover with this one, so getting them in will be tricky.

[RVF750]

Sonya,

I'm with Stalker on this, great show, but it's definitely spoilt a bit by the constant use of flight decks that are either very much simplified and fake or redressed onto very old chopped front ends.

Loads of professional pilots watch your show, and it just looks cheap and detracts from the quality of the show. The other show also does this and I know budgets preclude a lot of what could be done. A Simulator is about 400 per hour and would be far better if the lighting could be sorted and the back dressed to simulate the rear of the flight deck and door for when cabin crew interject.

Things lie the vibration gauge on the Kegworth incident only really become understandable when an actual Classic 737 instrument is depicted. The whole scenario can be loaded onto a proper simulator and everything but the final crash filmed real time for edit.

Best of luck.


D&T.

[DozyWannabe]

To be fair, I suspect only a small minority of viewers notice things like that. Limited budgets being what they are, I reckon it's better to spend money on getting the research right and getting the best contributors to weigh in.

The difference between the early -300 vibration gauge and that of the -400 can be demonstrated reasonably well using graphics, as the main difference is in the positioning of the indicator. Additionally, if I recall correctly, the misdiagnosis of which engine was having problems had more to do with insufficient conversion training - the -300 used bleed air from the right engine only, whereas the -400 used both.

[Centaurus]

I work for the television show "Air Crash Investigation" that airs on National Geographic channels around the world

While the Kegworth accident has been done to death in numerous articles, may I suggest you would do well to consider an Air Crash Investigation show on a little publicised crash (or rather ditching)to a Garuda Indonesia Boeing 737 that happened in Indonesia on 16 January 2002.

On descent into Yogyakarta the 737 encountered a 63,000 ft super-cell thunderstorm accompanied by turbulence and heavy rain. The weather radar on the aircraft was defective. As a result of the heavy rain which was well above the amount used for calculation of engine tolerance during certification testing, both engines flamed out while the aircraft was in cloud.

When the crew tried to start the APU in order to attempt to restart the engines, the aircraft battery failed due to a defective component and this in turn resulted in a total electrical failure. With no engines, and no electrical power the artificial horizon and compass system failed.

By sheer luck before control was lost in cloud, the aircraft came out of the side of the thunderstorm at 18,000 ft. More good luck when the crew saw a river winding through the jungle below. The pilot made a high speed ditching with no engines and no flaps and again luck was with them because the river was shallow and the aircraft did not sink. All aboard except one unfortunate flight attendant, survived the accident.

It is hard to believe that such an amazing combination of potentially fatal events happened in such a short time. Faulty weather radar which led the aircraft into a huge thunderstorm super-cell, a double flame-out caused by rain ten times more than the previously heaviest recorded, a defective battery, and total electrical failure resulting in loss of vital flight instruments that would normally result in loss of control in cloud. Try inventing that lot at the same time in a simulator and the instructor would be laughed out of the box.

I suggest this would be God given splendid story for your Air Accident Investigation TV series. PM me if you would like more detailed info on that accident.

[nitpicker330]

Pity the crew didn't do a windmill re-start......why didn't they try? 18,000' is still plenty of time to. Just accelerate to the correct IAS and they should start no problems at all after a blow out. An APU isn't required for that.
Did they lose the igniters as well??

Anyway too late now!!

[Captaintcas]

We had an exercise in the sim recently, dual flameout due volcanic ash at 14.000'. Windmill start required. I can tell you, it is very hard to dive to get the proper speed knowing that the ground is edging closer and closer very quickly and in IMC... It is key to be quick and to prioritize checklists in this exercise.

[No Fly Zone]

Please forgive my rudeness, but your TV show - and most others like it are bent on drama and trauma- not facts. Despite your inquiry, nothing of what you are told here is likely to make it into your program. If I'm wrong, my sincere apologies, but yet to see a TV program, even NG or BBC, that gets it right. Even when the details are explain to you, in the most simple terms, your kind still opt for the the High Dramatic effect. I won't help you do do that!

[B737900er]

No Fly Zone,

Im shocked your saying that seeing as your from the states. The yanks love trauma exaggeration and drama.

They even dramatise paint drying on a wall. Reliable sources have confirmed that the chemicals used in the paint have also been used in WMD in IIIIIIIraq :E

[flyboyike]

Please forgive my rudeness, but your TV show - and most others like it are bent on drama and trauma- not facts...but yet to see a TV program, even NG or BBC, that gets it right...


Nah, you're just being overly harsh. Captainincas says those shows are the best CRM tool since a cup of Starbucks with a blueberry scone.:p

[Centaurus]

Pity the crew didn't do a windmill re-start......why didn't they try

For obvious reasons I could not quote in Pprune the whole accident report chapter and verse. Otherwise I could have mentioned the fact the report stated the crew did try for windmill relight as soon as the engines were literally drowned in water. However they were still in extremely heavy rain while stuck in the thunderstorm and the Boeing investigation made the point that it is a waste of time trying to windmill relight while still in the conditions that caused the dual flameout in the first place.

Then when the load on the battery took place as an APU start was attempted, the already defective battery gave up the ghost completely. Thus no electrical power and no sparks to get the engines going. In short the crew were up sh#t creek without a paddle.

[sbuyting]

Thanks for all your comments. We're really proud of the fact so many aviation industry insiders follow our show and think highly of it. That said, we know our show is not perfect. We try our best to get the details right – from the research to the props and sets our Art Department builds. But the fact is, we are limited to what we can do due budgetary constraints and regulations with the actor's union, etc. We have a skeleton cockpit, which we try to build as accurately as possible for each of the planes we feature and only one cabin, which we only have limited ability to manipulate to customize for each flight.

With only 44-minutes for each episode, it's always a challenge to boil down the essence of an accident, the investigation, and safety lessons into a cohesive story.

Long story short, we appreciate you watching. We work hard at this show. And we take great pride in the fact we have this platform to spread the important safety lessons that come out of these tragedies.

To the one person who questioned the facts on our show, every word that's spoken on our show is independently fact-checked and annotated. I came to this forum because I've gotten great help here in the past. This time, I simply looking for some quick input, which thank you – I got yesterday and appreciate very much.

We've got a lot of interesting episodes coming up for Season 14 – some well known, others not. To all you steely-eyed aces, keep on keeping it safe!

[captplaystation]

Sonya,

I worked for BM at the time of the accident, and was actually made aware of the accident 1hr after it happened by Sim engineers when I emerged from the Orion/Britannia B737 Sim at EMA during my 737 Conversion course.

I knew both crew members personally, so have taken perhaps even more interest than the average Joe in the accident/investigation.

This accident has been done to death in CRM courses in every airline (and there have been a few) I have passed through.

Difficult to know what new ground/insight you can offer on this one.

A few minor/oft ignored points you may find interesting. The action of disengaging the autothrottle (at that time if I remember correctly the 1st item in the recall items for severe engine damage/fire on the 737-400) had the effect of smoothing the damaged engines operation (as the PMC was no longer fluctuating the fuel flow to try & compensate for the damaged engines inefficiency ) If I remember correctly Boeing subsequently reversed the order in the checklist (as I no longer fly the "Classic" I don't know which order it is done in now)

The vibration was so severe, that reading the vibration maters (particularly from the RHS where they were partly "masked" if on full deflection) robbed the crew of a vital parameter (which they later stated they wouldn't have placed much faith in , as the gauges were somewhat junk in the DC9 which was the Capt's previous type) The levels of vibration probably rendered the value of the other engine instrumentation to "useless", as testified by another crew in one of the 2 similar failures which succeeded this one & precluded the grounding of the type. There were no "warning lights" associated with this failure regime, an omission corrected in the instrumentation of the subsequent 737NG.

The fact that the incident happened more or less directly over EMA conspired against them, as they had no need to demand power from the damaged engine until a very late stage of the approach , an extended routing to some other airport would have shown up the deficiency in the remaining engine much sooner & "may" have given them time to relight the one they had shut down.

Boeing/CFM were allowed to certify the new variant of the CFM56 by ground testing only, even if it was in fact substantially different to previous versions , because it was a"variant" rather than a new engine. The deficiencies inherent in the design (vibration at high altitude) were therefore not identified.

The accident showed up many technical deficiencies in many other inspected aircraft concerning their wiring of fire extinguishing/detection systems (cross wiring etc) as there was at one stage a suspicion (later disproved) that the wrong fire warning may have activated. . . nonetheless it was a slap in the face for Boeings Q.C.

Saddest fact of all, is that, for the sake of a couple of hundred metres of flat undershoot (or a different runway ) they would probably have gotten away with collapsed gear/some back injuries. How they managed to land on a busy motorway without hurting anyone in a vehicle is a miracle.

We should always remember that Kevin & Dave were both affable average ability line-pilots, and despite the very public/personal comments made by BM management & the engineering biased chief investigator, this COULD have (in reality) quite probably happened to a large percentage of us.

[DozyWannabe]

Difficult to know what new ground/insight you can offer on this one.

To pilots and enthusiasts, probably not much - but the audience is somewhat broader.

The fact that the incident happened more or less directly over EMA conspired against them, as they had no need to demand power from the damaged engine until a very late stage of the approach...

Possibly. As I recall, another issue was the frequency of radio transmissions. The Captain was in fact interrupted during an attempt to review the symptoms and re-assess the situation.

We should always remember that Kevin & Dave were both affable average ability line-pilots...

Interesting that you should say that - one of the books I read covering the subject advanced the opinion that the Captain had a reputation as "something of a martinet". Said book has proven inaccurate in several ways since, and I'd be interested to check the veracity of the claim (via PM if preferred).

[munster]

Air Crash Investigation.
The TV drama that found an innocent engineer guilty of causing the Helios crash, grossly prejudicing his chance of a fair trial.
Stick to fiction. It's what you're best at!

[DozyWannabe]

The TV drama that found an innocent engineer guilty of causing the Helios crash, grossly prejudicing his chance of a fair trial.

Rubbish. The episode concerned made it clear that the switch should have been checked by the crew during pre-flight and was not. Additionally, the ground engineer who performed the test specifically requested the crew to check the switch was set to "AUTO", a request that was apparently ignored.

To which engineer are you referring?

[superwbd]

I, along with a team of pilots, engineers, ATCs, have been translating your series, Air Crash Investigation into Chinese for years. Though,, some of your Chinese audiences are raising concerns about the effects may be off the real scenarios, there is no doubt that Mayday is one of the best aviation-related TV show in the history. As for myself, for those who are newbies with aviation, the first show I would recommend to them is Mayday, and it never let anyone down.

Thanks again for your team's hard-working and professional attitude. Your job is really fascinating.

[ANZpilot]

That Air New Zealand cabin is totally wrong in Deadly Test. We never had the koru on the walls like that, they were usually just plain. Could you also spill the beans on some other episodes? The pilots here all love the show