A340 long take-off

[davidash]

As a passenger on a fully loaded A340-200 out of Johannesburg a few weeks ago, I timed the take-off roll and noticed that we rotated at 58 seconds. I know the airport is high but the temperature was about 14 degrees C. In all my years of travelling I have never had such a long take-off roll. Most aircraft manage a maximum of 52 seconds. The return flight out of LHR on a fairly full A340-600 lifted off at 42 seconds. Any comments?

[Final 3 Greens]

My comments are not expert, but ....

The A340-200 and -600 have different engines and presumably power/weight ratios, this could be a factor

The departure at JHB may have been a reduced power takeoff to save engine wear and will have been calculated - the pilots will have known the distance required to take off and this could be a factor in the time

The headwind/tailwind component on take off has an impact on the time required to break ground, this may have been a factor

The aircraft performance may have been affected by loading (we don't know what the gross weight was)

Finally, JHB is appx 5,500 feet above sea level, LHR is appx 80 feet - this wil ldefinitely have an impact on take off performance (the combination of temperature and pressure altitude is known as density altitude)

To give an example, when flying a PA28 (light single engined aircraft) out of an airfield in the LA basin (300 feet above sea level), the take off run on a 20 deg C day, calm winds, was approximately 400m.

Returning the same day, from an airport with an elevation of 6'700 feet and 14 deg C, the take off roll was at least double (I can't remember the exact numbers, it was 13 years ago.)

Obviously big aircraft dynamics will be different to tiddlers, but you get my drift?

[TopBunk]

Whenever I see an A340-200/300 at JNB taking off, it always makes me glad that I fly B747-400's.

Those CFM engined A340's always seem to have marginal performance almost everywhere - but at a hot and high JNB, I shudder to think what the performance would be like if they lost an engine:eek:

58 seconds sounds not unreasonable.

[Rainboe]

747-200 out of JNB for LHR used to do 55 seconds. Even the 747-400 out of a hot and sultry BKK for LHR were 55 seconds. At those sort of speeds, most people would not reject above about 10 kts below V1. What is important is at that time up to getting airborne, most people must have exactly the right reactions. In practice, those critical moments of engine out performance could well lead to a 'negative climb gradient'. On those take-offs discussed, little, if any, thrust reductions will be used- there is usually hardly any latitude for them. They're are very good for blowing the soot out of the engines!

[Skipness One Echo]

I shudder to think what the performance would be like if they lost an engine
It would be within established safety parameters worked out beforehand. Stop shuddering.

[shalo]

Having flown out of JHB dozens of times on several different aircraft I know what you are thinking. The first time I left on an A342 Ialso felt like it was the longest take off roll of my life but thats what the A342 is all about. Most likely (as has already been said) it was a reduced power take off to reduce engine wear.
As it happens, I personnaly felt that although the roll was quite long, the take off itself from JHB was so smooth and comfortable (on the A342) that I was sat wondering at the difference compared to say the 767 where you can really feel the power pulling you back on departure.
Happy flying and enjoy the A340 - a wonderful aircraft.

[Contacttower]

The early A340s are renowned for there lack of performance, I wouldn't worry though, OR Tambo has one of the longest runways of any airport, 03L/21R is almost 4.5kms long.

[PAXboy]

davidash I rolled down JNB 03L last Tuesday evening in a 744 but have done so in 747-100/200/300s and 340-200/600s. I do not keep a record of the time of take off rolls at JNB (or anywhere!) but last week's was certainly around the 55 second mark, I do recall having had rolls there in excess of 60 seconds. Time of the year (temperature) affects this along with all the other factors mentioned.

It is usual for the long hauls to depart from 03L/21R although it is usually 03 and the Europeans like that as it gets them off in the right direction - right over my sister's house in Pretoria!

[simfly]

on the opposite end of the scale..... Have just had the pleasure of paxing on Thai BKK-HKT and return, both on B744 with 1 hour 5 mins flight time... The flight BKK-HKT was almost empty, and the acceleration was like nothing I'd felt on any airliner before!! It was no more than 20 seconds to wheels off! Climbed like a rocket!

[HighFlyingSpanner]

David

Please please please do not tell me you sat with a stopwatch timing the takeoff?

[Final 3 Greens]

Watch out, there's a troll about :=

[BladePilot]

Was priviliged to fly with Capt Andy Alsop way back on occasion when he did Westray - Papa Westray, Orkney Isles, Scotland in just a tad over 59 seconds, his record for that flight stands at an amazing 58 seconds in a Britten Norman Islander! so we were just outside of the record, amazing flight and an amazing bloke. Entire flight was as long as your take off run! :)