Jet 737 aborts takeoff, leaves runway - Goa
 

Initial reports saying starboard engine reversor deployed during T/O roll

The starboard reverser does appear activated from this pic

http://i.imgur.com/FRICyfS.jpghttp://i.imgur.com/IIU4COQ.jpg

https://www.flightradar24.com/data/f...w2374/#bffd8f3

Flight radar picture shows it heading into the rough just after commencing takeoff roll at the threshold.

Data shows about 35 kts reached on the runway.......:sad:

What a weird place to end up.
Could be the reverser locked in after takeoff thrust causing it to veer hard right and end up where it did?


http://www.pprune.org/attachment.php...1&d=1482821489

I imagine it would spin like a top if that actually happened.

I seems Sky news would agree ...
Fifteen hurt as plane spins 360 degrees during take-off in Goa

Geometry was never Sky News's strong point. :O

The aircraft appears to have come to rest approximately 250 m north of the runway abeam the aiming point and on a roughly reciprocal heading, adjacent to the airside road at the point where a path leads off to the GS antenna.

I think you need to reel you wild imagination in :ugh::ugh:

Poor Quality Toys
 

...or get a better spinning top.

Sounds like pressing TOGA with an asymmetric engine speed, most likely caused by having one engine at a higher setting during the 180 degree turn at the node.

If #1 thrust had been used to help turn the aircraft while #2 stayed at idle, and then TOGA was pressed before allowing both engines to stabilise, you could easily lose control. #1 would accelerate much quicker to TO thrust, while #2 would have to accelerate from idle.

Never flown the 73, but I've ridden the jumpiest many times before. Those CFMs have a very long spool up time from idle. If the pilot was distracted or didn't get on top of it quickly enough, things can very quickly turn pear-shaped.

Squawk7700

that scenario happened to a 738 at a company related to mine. Departed the intended runway but luckily ended up on the crossing strip. Highly likely in this scenario, imo.

In this day and age uncommanded reverser deployment would be very unlikely

I believe that you can command a single reverser to deploy when on the ground. But why in this case would be the next question.

Sqwak7700

Plausible

If you get, for whatever reason, a big thrust asymmetry at LOW speed, this is the likely result.

ie you are below VMCG and VMCA.

What's going to keep it straight? Not rudder certainly.

Sure, pulling both to idle will save the day- but if you weren't trained for, or expecting it, a low speed asymmetric yaw will ceretainly punt you off the runway.

Of course, most engine failures happen just as one passes V1....:rolleyes:

Nice graphics and analysis as before. :ok:

From your article linked above:

Actually, I think the brakes will normally be released before the initial spool up per Boeing's recommendation.

I found this, allegedly from a 737-700 FCOM:

Similar verbiage is in the manuals for the larger Boeing's I've flown.

How many of you use differential thrust to help turn a 737 ?
One engine spooling up with the other lagging behind will push the nose sideways, but you need to be really slow not to catch this.

And, you would go to the side with not much forward movement.

AtomKraft has it spot on I think. Very few are trained or expecting massive asymmetrical thrust at low speed. Governor failure could give you a similar outcome.

Are you serious?
We are all trained to recognise engine failures during takeoff at various speeds.
If you start your takeoff on one engine you will do a pirouette where you stand.
An engine seizure or a reverser deployed at "low" speed fits the scenario. If so it was handled poorly.

You know, being trained for stuff makes a BIG difference.

For example, I've flown a RJ-85 to a dead stick landing. (in the sim) . Had the guys who ran out of fuel recently done that? I don't know, but I cocked it up badly the first time....

Ever tried an engine failure just as max thrust is reached? At low speed? Hardly the most unlikely time for an engine failure, is it?

Off you go!

Unlikely to kill anyone though....

Off you go. To the side. A few metres down the runway.
I have trained this, and I have tried it in real life. My Effoh who was in the habit of not setting 40%, but rather just push the throttles up (that is the way we used to do it on the .... fill in the blanks) did exactly that, and hit TOGA without checking anything. The left engine worked as it should, the right was not. Not an engine failure, just slow.
The nose was pushed about 2 metres to the side before I managed to close the throttles. Maybe we managed to move 10 metres down the runway.

Playing glider in the sim is a different situation to doing it in real life, in darkness and without visual contact with anything.

One of the first things practiced in Multi-Engine school. The swing is just as bad, i.e. uncontrollable, in a Seneca as it is in 737. Seems like modern aviators have forgotten the basics, if this happens to be the case of asymmetric spool up. As an instructor I always sat with my left hand on the mixture control < 1000 ft with new schoolers. They were good, it was just that I wanted to immediately get control of the yaw if they didn't respond properly to the failure.

True but

Your training presumes a lack of thrust on one engine at speed (rudder skill) and not a significant overthrust on one engine below rudder effectiveness.

And the confusion is compounded with any reversers deployed trying to figure out what end is pushing or pulling too much.

Most pilots simply end up off the side of the runway while they are deciding (data based)

172 Driver.

No. It's not.

I've got over 12000 hours and only seen it on one of my type conversions, and that only briefly

Does this runway require a backtrack and 180 degree turn? How many times have I seen guys spool up the outboard engine to assist the turn (that's fine)....close the levers as they line up and then stand them up to 50% when cleared for T/O....but the spooling down engine hasn't fully idled and so it spools up faster than the other.......if you don't check for both stable at 50%.....you're going to get a big yaw. Does this runway require TOGA?

On the face of it this seems like simply not checking for BOTH stable before applying required take off thrust.

Yup, requires backtrack. I wouldn't imagine the 73 would need the assistance of the outboard to make the turn though. I'm from Goa and I can't remember the last time differential thrust was used to assist and can honestly say I've never had any of them go to TO thrust straight from the turn.

Having said that, this could very well be the case here.

Ok, wild imagination reeled in.
I was responding to If that happened, I stick with my original statement. I don't believe that this is what happened though. I have seen many experienced pilots depart the runway in the sim if an engine is failed at about 25 kts, and it happens in real life when one engine spools up quicker than the other. When a 737 aircraft departed runway 16R in YSSY some years ago and ended up on 07, the crew thought they had a nose wheel problem. The problem was that the right engine came up slower than the left. The nose wheel simply scrubbed along the Tarmac when NWS was used.
Like someone above said, the chances of having a reverser deployed at the start of the takeoff roll are remote.

I am not going to speak for you of course, but are you sure you never practiced the scenario in multi-engine twin prop (be it a Seneca, Duchess or Baron) all those years ago getting your Multi-Eninge rating?

I have done engine runaway during recurrent training in a 737, but guess that is something the operator has chosen to put in the program.

To the B737 experts,
Can a fault induce auto deployment of the reversers while the thrust levers are out of idle posn...?

I well remember the night of V1 cut after V1 cut in the 737 sim when the instructor asked us, "got the hang of it then?" and on receiving our cocky assurances set us up one last exercise.

The beefer chopped one engine as soon as they had reached t/o N1 at perhaps 40Kts. The resulting excursion was astonishing. As was the following one. It took IMMEDIATE and EXTREME control inputs to control the swing.
By FAR the hardest EFATO drill on the 737 (and A320) is the low-speed failure with full power when no rudder authority is available to help keeping it straight. Partly because we tend to practice it less I suppose, after all, a low speed asymmetric event can't be a big deal, can it? Hell no!

The excursion of this event looks to me as if a low speed full power failure was not properly contained.

Does the CFM engine have a "keep out" band like the IAE ? If the thrust levers were splayed to assist the turn and advanced towards take off thrust while still in this position, would the FADEC rapidly accelerate the leading engine through the keep out range whilst the other engine lagged behind ?

The surprise factor would be considerable but even so they still went a long way off the pavement.

No keep out zone on the CFM (that's pretty much a Rolls exclusive due to fan flutter issues).
While an uncommanded reverser deployment is very remote, it is somewhat more likely on the ground than it is in flight due to the air/ground logic.

Same here, Goat, but on 747s. Luckily, the pilots reacted fast enough and rejected the TOs before they turned into an offroading adventure.

Has become a serious enough threat that our FDAP now tracks this. On our airplanes it is assuring you have approximately 1.1 EPR or 45% N1, depending on model, before pressing TOGA.

Forgive my ignorance here, if any...

I've seen many backtrack 180 take off's on the 737 (and 320) and as far as I can remember, the turn itself involves both engines with N1 at about 40% to accomplish the turn. I have never seen differential thrust being used on the 737 to assist a 180. This means, both engines are already symmetrically spooled and once the a/c is lined up and the PF advances the throttle levers (TOGA switch), both levers move forward in unison to T/O thrust with A/T armed, assisted by the FADEC.

I have not seen engines set to idle N1 at intersection T/Os or before T/O after completing the 180, unless T/O clearance has not been obtained or the crew is waiting for another a/c to clear the runway, a frequent scenario at Goa.

Could it be that FADEC was malfunctioning?

Stop judging: Pilot of Jet Airways Goa runway crash writes a strong letter
 

Excellent. Good on him! Wish he had added to the media to stop painting commercial aviation as unsafe and making the public fearful, when in fact it's a safety record to be damn proud of. And yes, contrary to popular diatribe, pilots actually fly airliners.

That letter should be on every editor's and sub-editor's wall and perhaps at the beginning of every accident/incident thread on Pprune.

Just for the sake of clarity... The above-linked opinion piece was written by some random guy who had nothing to do with the incident. As for the misleading headline that appears on that site, I'm sure he had no part of it.

The way it is worded I don't believe for one moment that it's written by the pilot involved.

I don't think the crew would be allowed to write anything about the incident, even a sentimental piece like this, before the full enquiry was concluded. An anonymous guy from the same company perhaps.