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??

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

[ImbracableCrunk]

Lessons Learned

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]

Originally Posted by stalker

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.