Centaurus
4th Mar 2013, 11:25
DHL Boeing 727 over-runs the runway in Africa at high speed due unstable approach in rain and tailwind shear. I thought I would place this in this forum rather than Pprune Tech Log Forum as it has some Australian experience input.
http://www.aib.gov.ng/reports/AIB-DHL-2006-09-07-F.pdf
Two items of interest caught my attention on reading this report. Firstly, I recall talking a few days after the accident to a friend of mine who was the pilot of a 737 that landed a few moments before the 727. The 737 pilot experienced a strong tailwind shear shortly before touch down in heavy rain. He pulled up normally and while taxiing suggested to ATC that the following aircraft (the DHL 727) be warned of the tailwind shear.
So ATC did the right thing and told the 727 pilot, who replied rudely "Shut up -we are busy" That remark is not quoted verbatum in the accident report only that an "inappropriate" comment was made by the 727 pilot in response to the ATC call. Too right he was busy - making a bloody awful approach when he should have gone around.
Secondly, the report indicates that during the flurry of cockpit activity that occurred after touch down of the 727 (30 knots faster than Vref), the first officer who was doing the landing, quickly selected full reverse after touch down half way down the runway, then suddenly cancelled reverse.
The FDR revealed a sudden aircraft acceleration as the reverse was cancelled and it was this acceleration that was partially responsible for the over-run. The 727 was in trouble already due to the stuffed up approach by the F/O and his sudden cancellation of reverse causing momentary acceleration, only exacerbated the already dire situation.
Experience from observing simulator sessions in the 737 in Australia, reveals that many pilots do not know the exact position of the reverse idle detent. Because of this they will often move the reverse thrust levers fully down, instead of stopping their movement at the reverse idle detent. When this happens, the engines are still spooling down from high power - with the result that when out of reverse, the engines are still delivering significant forward thrust while in the process of spooling down to idle. This causes momentary acceleration of the aircraft which increases the landing roll. This is what happened in the DHL 727.
This point becomes quite serious when you look at the use of reverse thrust on a slippery runway in a crosswind, where instant reduction to reverse idle is required to prevent weather-vaning into the crosswind. The morale of the story is that simulator instructors should try to allow time for pilots to practice playing with the reverse thrust levers so that they are familiar with the actions needed to find the reverse thrust detent quickly, without overshooting into inadvertent full cancellation of reverse thrust.
http://www.aib.gov.ng/reports/AIB-DHL-2006-09-07-F.pdf
Two items of interest caught my attention on reading this report. Firstly, I recall talking a few days after the accident to a friend of mine who was the pilot of a 737 that landed a few moments before the 727. The 737 pilot experienced a strong tailwind shear shortly before touch down in heavy rain. He pulled up normally and while taxiing suggested to ATC that the following aircraft (the DHL 727) be warned of the tailwind shear.
So ATC did the right thing and told the 727 pilot, who replied rudely "Shut up -we are busy" That remark is not quoted verbatum in the accident report only that an "inappropriate" comment was made by the 727 pilot in response to the ATC call. Too right he was busy - making a bloody awful approach when he should have gone around.
Secondly, the report indicates that during the flurry of cockpit activity that occurred after touch down of the 727 (30 knots faster than Vref), the first officer who was doing the landing, quickly selected full reverse after touch down half way down the runway, then suddenly cancelled reverse.
The FDR revealed a sudden aircraft acceleration as the reverse was cancelled and it was this acceleration that was partially responsible for the over-run. The 727 was in trouble already due to the stuffed up approach by the F/O and his sudden cancellation of reverse causing momentary acceleration, only exacerbated the already dire situation.
Experience from observing simulator sessions in the 737 in Australia, reveals that many pilots do not know the exact position of the reverse idle detent. Because of this they will often move the reverse thrust levers fully down, instead of stopping their movement at the reverse idle detent. When this happens, the engines are still spooling down from high power - with the result that when out of reverse, the engines are still delivering significant forward thrust while in the process of spooling down to idle. This causes momentary acceleration of the aircraft which increases the landing roll. This is what happened in the DHL 727.
This point becomes quite serious when you look at the use of reverse thrust on a slippery runway in a crosswind, where instant reduction to reverse idle is required to prevent weather-vaning into the crosswind. The morale of the story is that simulator instructors should try to allow time for pilots to practice playing with the reverse thrust levers so that they are familiar with the actions needed to find the reverse thrust detent quickly, without overshooting into inadvertent full cancellation of reverse thrust.