Incident - Incorrect thrust setting for takeoff
 

Fortunately no LOC antenna or runway lights involved this time. Take care out there boys and girls. This is one those 'can kill ya' type things if you get it wrong.

Investigation: AO-2012-022 - Pre-flight planning event - Airbus A320, VH-JQX, Sydney Airport, 6 February 2012

Jetstar takeoff error at Sydney causes ATSB investigation | Plane Talking

Tick Tock
 

I only fly lighties, but wouldn't you get to a certain distance down the runway, get an odd feeling about lack of acceleration/airspeed and runway remaining, and I dunno, manually increase thrust?

I've said it before, and I'll say it again. A timed acceleration check will stop this type of error ending up in an accident instead of an incident.

Yep 'phoon most would or reject if this is the case here.

Why ASA and CASA do not put J* in the same basket as Tiger has got me buggered. Surely there must be some heat put onto someone about the inconsistencies in the way they pick and choose who they investigate, ultimately the traveling public are involved.

Let's just hope one day someone like BB is held accountable properly....

You get what you pay for I guess.

Yes , it's called experience and that feeling in the seat of your pants. In 737 if you haven't hit 80 knots by 1500 foot markers something's wrong.

Typhoon.

I can only speak from the environment I operate in.

There are multiple opportunities to ensure the thrust is correct.

1. Is the thrust setting reasonable for the runway in use & aircraft weight. That comes with experience.

2. All pilots independently calculate the required thrust for takeoff.

3. When the PF briefs the thrust required for takeoff, actually check that this is the thrust that is set.

4. After engine start. My own experience has led me to check the thrust is correctly set. Electrical spikes after engine start on the aircraft I fly has caused the thrust setting to default back to maximum takeoff thrust.

5. Check the thrust setting prior to entering the runway. This is a company requirement. In case there is a runway change or departing from an intersection other than that planned.

6. Normal takeoff acceleration will see the 80kt call around about the 1000 foot markers (in the aircraft I fly) if the takeoff commenced at full length. Other than full length, it takes the same time to set takeoff thrust, check engine parameters & get out the 80 kts call.

MC

Also as the thrust is set based on runway takeoff data, one needs to make sure the wts used for this data is correct. With 30min turn arounds mistakes can and do happen. The old swiss cheese.

Senator-
 

We have it covered - trust us.

We know how to do this

:D

inandout said-- Exactly, wieghts need to be triple checked too, as Emirates found out in their very narrow escape from a major disaster in MEL a few yrs back!!!

I think, from memory it was an entry error of 100 tonnes lighter than actual as the 1st and 2nd digits of the weight were swapped on entry??

Can someone who flies ops in a 3 man or more crew please tell me how with whatever the company SOP is to prevent this and at least 3 people supposedly independently cross checking the data entries and subsequent V speed and thrust setting results no one picked, eg 230 instead of 320 tonnes being used in the takeoff calcs???
1 person makes an error and the SOP check fails and 2 others confirm the error as correct???
I'm sorry, I know anything is possible under the right mix of circumstances but I am still at a loss to understand how this actually happened without being detected until it was very nearly too late in the take off.

These types of errors happen more than we would know I suspect. Most get picked up b4 power up. Humans make mistakes & we all know that fatigue (not saying it is the case here), high levels of automation & the saving of $$$ all adds up to a risk level that's getting higher.
Flex temp T/Off (reduced T/off thrust) is purely to save the engines with less wear & tear as we operate out of Rwy's longer than actually needed but that comes at a cost as we have seen here in this latest J* event.
The basic fix for this scenario is go max thrust on every T/off but that costs $$$$, something that aviation now revolves round more than safety!

I do a gross error check on the weights of the 'bus' in my head b4 I/we launch, old school I guess. Eg. 43 tonne Op Wt machine (Fleet average rounded up). 8 tonnes gas (typical 2 hr sector). 180 seats (A320) I round that up to 16 tonnes for a full ship(allows for average bags under floor also).That's 67 Tonnes as we trundle out to the black stuff (Rwy). The actual current GW of the 'Bus' is always displayed on the bottom R/H side of the SD screen when the plane is 'alive' so I compare that to what I worked out in my head, it's always within a tonne or so often a few 100 Kg's, not enuf diff to effect the T/Off drastically. Obviously the exact figures have been worked & entered but there in lies the possible error as is the subject of this discussion.

It will happen again you can count on it !


Wmk2

Smart man :ok:

(your type is not wanted on Jetstar flight deks)

I wonder if cumulative fatigue will be found to be a factor?

Wasn't it about about 6-7 years ago that Joyce famously told a forum that Jetstar would be burning out it's pilots in 6-7 years with its rostering practices?

http://www.pprune.org/dg-p-reporting...xpectancy.html

Aussie-the augment crew, by SOP, were required to report tired and ready to rest. They are not involved in the performance data-it is a 2 man operation (in actuality the SOP at the time specified that that they not be involved in the pre-departure process -including maybe doing walkaround or similar-due to having to report ready to rest). Self preservation is another issue, but the bottom line is the only reason augment crew are physically in the cockpit for departure is that you can't occupy the CRC for T/O and Landing, and are not allocated a pax seat. It is a 2 pilot cockpit and 2 pilot op.

Not neccesarily. If they were going off the short runway in YSSY then the aircraft could have had insuffcient thrust set while at the same time feeling positively lively compared to if they had gone off the long runway.
So....insuffcient thrust can provide quite brisk accelleration compared to the correct amount of thrust on a different runway. Hope that helps explain how it can happen Typhoon.

Due you count intersection departures in that statement:E

Interesting to note that in the Emirates incident in MEL none of the crew noticed a slow rate of acceleration and that was in a heavy aeroplane with a huge error in the thrust calculation.

Can't comment on the A320 but does the Flex Temp setting change the rate of acceleration in that thing?

I can assure readers from personal experience that the detection of slower than expected acceleration is difficult particularly at night. It is only until almost at the end of the runway when you realise something is wrong. Rather like overtaking a vehicle going 10 kms slower than you on a freeway. While a long way behind the vehicle the rate of closure seems very slow then as you draw alongside you are now conscious of almost speeding past the vehicle.

Nearly 30 years ago, an Air Nauru 737-200 lined up for a night take off from the 5600 ft length runway on Nauru. No overun area - just boulders and a 20 feet drop into the water. Max bleeds off take off due runway performance limited. Planned EPR 2.18 which is full power.

80 knot call made by the captain who was PNF. Passing 110 knots the 737 would normally be passing abeam the control tower which is close to the runway. Very black hole take off over water. It was only when about five runway lights were left to go when the penny dropped that the 737 was well below V1 and never going to get airborne in the remaining runway length. An abort was now out of the question so the captain took control and fire-walled both thrust levers against the mechanical stops at the same time hauling back on the control wheel. The jet blast lifted concrete from the perimeter road back along the runway.

Later investigation revealed that at no point during the take off roll did the engines develop full thrust - although both EPR gauges indicated full 2.18 EPR thrust was achieved. In fact, it was calculated later the EPR gauges had over-read by nearly ten percent which resulted in significantly reduced thrust. The trouble was caused by the engines inlet sensors called Pt2 tubes which were later found to be blocked by a combination of phosphate dust and insects because engine covers were not in place overnight.

Close inspection of the N1 compressor gauges on the instrument panel would have revealed the lower than expected N1 readings during take off but for various reasons none of the three crew members in the cockpit that night double checked the N1 readings against the indicated EPR digital read-outs.

It was an almost identical situation to that of the 737-200 that crashed into the Washington Potomac River due to iced up Pt2 sensors on both engines that resulted in faulty EPR readings. In that case the F/O as PF was aware that `something was not quite right`during the take off roll but was unable to pin-point the problem which was lack of expected acceleration.

The captain failed to fire-wall the engines and the 737 clipped a bridge and crashed into the river killing most on board. Fortunately the captain of the Air Nauru aircraft did fire-wall the engines at the last few seconds of the take off roll and that saved the day.

Putting aside the blame-game that later ensued where the Air Nauru captain was hung out to dry by management, it was clear to this writer (I was in the jump seat) that the slower than normal full power acceleration during the take off roll at Nauru was never enough to alert the crew to an impending serious accident because the sensation was so subtle. The dark night scene didn't help. It was only in the last few seconds of the take off roll that a positive picture of the true situation became apparent. All three crew members were fooled.

The same take off thrust actually achieved that night during the majority of the take off roll at Nauru, was identical to the reduced thrust settings used on longer runways such as Guam or Hong Kong when calculated by the Assumed Temperature method. That was around 2.10 EPR. The difference of throttle angle between 2.18 EPR and 2.10 EPR is quite small. The clue was in the readings of the N1 compressor where the instrument dial is quite small and N1 needle readings small scale and hard to see at night.

Ironically if one only engine Pt2 sensor had been blocked at the time of the incident, the subsequent split throttle position needed to set equal EPR needle readings would have alerted the crew early enough in the initial take off roll to safely reject the take off. In fact this had happened to another crew on Nauru a few weeks earlier. It was an unfortunate quirk of fate that both engine Pt2 sensors suffered similar blockages leaving both EPR gauges giving identical readings as expected during a normal take off.

One trick this SLF learnt years ago in the RNZAF days (from an aborted takeoff). Set your stop watch at start of takeoff roll. If you have still not rotated after 45 seconds get ready for the worst and make sure you have the nearest exit mapped in your mind. Pretty much works for most a/c types flying out there. When I put my life in some junior jocks hands, I want to know that I still have a little bit of control over a stuff up. Shabu Shabu anyone?

The ATSB report states the time was close to midday.

Could have been dark, was there an eclipse this week? :suspect: