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DHL Boeing 757 Crashes at San Jose, Costa Rica
A DHL Boeing 757-200F freighter crashed at San Jose, Costa Rica. The aircraft a 22 year old Boeing 757-200 with registration HP-2010DAE departed San Jose, Costa Rica bound for Guatemala City, Guatemala... (www.aviationweekly.org) और अधिक...Sort type: [Top] [Newest]
ay be wrong, but looks like they locked up the brakes blew tires and lost directional control, exiting the runway. With a near 10k runway, they likely could have firmly landed, used idle reverse and minimal brakes, assisted by aero braking and drifted to a taxi speed by the end of the runway, even with 20 flap landing speeds. In too much of a rush to stop? Have not flown the 757 for over a decade, but as I recall, the anti-skid still will work on standby brakes. Wondering if they lost all L hyd fluid and the PTU? If so then no nose wheel steering, auto speed brake and requiring alternate landing gear extension and slow electric flap lowering, making for a heavy workload. They did the right thing holding, getting weight down and making time to take care of the non-urgent problems before the approach.
Blancolirio did a video on this. He is a 777 driver and also flew 757's so knows the plane intimately. He shows which hydraulic system was inop, by noting which of the 12 spoiler panels did not deploy. Appears the Left hydraulic system was inop.
The plane had no nosewheel steering, nor any left engine reverse thrust. Steering below 80 knots was only via differential braking. It appears they tried to turn off a high speed taxiway, which is 2800 feet before the end of the runway - and misjudged or the attempted turn went bad.
https://www.youtube.com/watch?v=qPk23hPooKY
Also taking this runway, was with a 9 knot tailwind. And the vref was high because you can only use 20 deg flaps with these failures. So they were fast regards ground speed, but the attempted turn off 2800 feet before end of runway is the problem.
And this very plane had hydraulic problems back in Feb too.
The plane had no nosewheel steering, nor any left engine reverse thrust. Steering below 80 knots was only via differential braking. It appears they tried to turn off a high speed taxiway, which is 2800 feet before the end of the runway - and misjudged or the attempted turn went bad.
https://www.youtube.com/watch?v=qPk23hPooKY
Also taking this runway, was with a 9 knot tailwind. And the vref was high because you can only use 20 deg flaps with these failures. So they were fast regards ground speed, but the attempted turn off 2800 feet before end of runway is the problem.
And this very plane had hydraulic problems back in Feb too.
Dan I agree with most of your writeup, except "... they tried to turn off a high speed taxiway.."
S. Hrdacky's avherald site shows pictures of skidmarks before and after the point of reported "turnoff". Skidmarks indicate that Left and Right main gear brakes were completely locked up.
It had lost left side hydraulic system, so the plane had lost nosewheel steering. Then it lost directional control by rudder, when ground speed went below 80 knots. So I wouldn't call it a turn ; more like skidding forces and wind dynamics caused the abrupt turnoff. just my two cents.
S. Hrdacky's avherald site shows pictures of skidmarks before and after the point of reported "turnoff". Skidmarks indicate that Left and Right main gear brakes were completely locked up.
It had lost left side hydraulic system, so the plane had lost nosewheel steering. Then it lost directional control by rudder, when ground speed went below 80 knots. So I wouldn't call it a turn ; more like skidding forces and wind dynamics caused the abrupt turnoff. just my two cents.
Well you can still steer via differential braking... But as Juan indicates in his video, it is puzzling why anti lock did not prevent skidding - anti lock should still have been operational.
I noticed in the original video that the left engine appeared way above idle as plane whips around to the right - which also makes no sense as you cannot deploy the spoilers unless both engines are at idle....
Perhaps with left reverser inop - pilots pulled both reverse levers and that put both engines at some percent power above idle, but with no reverse actuation on the left engine, it produced forward thrust while right had reverse thrust - which would make it turn hard right as we see.
I noticed in the original video that the left engine appeared way above idle as plane whips around to the right - which also makes no sense as you cannot deploy the spoilers unless both engines are at idle....
Perhaps with left reverser inop - pilots pulled both reverse levers and that put both engines at some percent power above idle, but with no reverse actuation on the left engine, it produced forward thrust while right had reverse thrust - which would make it turn hard right as we see.
Indeed. A bad corporate decision that I am certain they regret to this day. Poor corporate decision-making. And the ()*()s that made that decision are most likely still at Boeing. Shame on the Board of Directors who let greed trump good business acumen. Sad example of an American focus on $$$$$$s. All of course IMHO.
If only Boeing hadn't stopped making the 757.