The initial image in the news looked liked the pilot was doing his damnedest to avoid collision. More prosaically, it really does look from the dashcams like it’s in stall as soon as we see it, and the left wing stalled over the bridge, either due to incredibly low airspeed or a final desperate input from the pilot.
You can tell by the way it’s ‘floating’ downwards - it’s not flying, it’s being held up by the cushion of air impeding the travel of the massive wing. Nose slightly up.
Maybe engine failure caused lack of thrust and hence inadequate speed for flight, pilot got the nose up enough to clear the tall buildings, and knew that was his last resort.
But dual engine failure on an ATR-72 on takeoff? It’s a modern and reliable plane, the odds are astronomic. Although it certainly seems like it. (Props are spinning, but could be windmilling if the pilots didn’t have time to feather.) The plane has taken off and is well out of ground effect. As it comes over the buildings it is nose high and seems to be under control. The final roll isn’t under control - I don’t think that the ATR-72 has that kind of roll control authority, especially at such a slow speed.
It shouldn’t be disorientation with good visibility. It brings to mind the Air Florida crash in D.C., with a failure to climb away after takeoff. (Of course, that was due to an engine thrust indication problem.)
A Reuters article I read this morning noted that the pilots’ last radio call informed tower that the left engine had flamed out, and while the ATR can sustain flight with one engine, it certainly can’t provide enough thrust for a successful takeoff.
The article also made mention of the pilots outstanding judgement and flying skills in avoiding the rather dense residential/commercial areas to crash into the river–both pilots were killed in the event.
Edit: As both a word nerd and a fan of airplanes/flying, thank you for using the phrase, “roll control authority” because it’s beautiful.
Some cursory searches didn’t yield anything useful, but I’d like to know the load limits necessary for that cert because I don’t believe it’s possible for a single-engine turboprop to climb out with a full fuel/cargo/pax load.
That said, I’ll keep looking for information in that regard, and I’m happy to be disabused of the notion.
My experience comes with large 4-engine cargo aircraft, and the thought of doing a single-engine takeoff with practically any load is…well…not a scenario I ever hope to be in.
I’ll try to dig something out. The cert is for a single engine failed, not a single engine working though, so it’s easier to meet for a 4 engine aircraft (3 engine t/o, not 1).
The requisite regulations are FAR Part 25 / EASA CS-25 (I assume this is an EASA certified aircraft because it’s Franco-Italian, but I think the wording is the same).
I found articles to that effect last night as well. So it sounds like a single engine failure at some time after V1 (the point at which the plane must take off). Any commercial plane can continue to climb away from the runway after V1 if properly handled with one engine failed and clear obstructions. An engine can completely fail at any point after V1 (even before rotation) and the plane will climb away and avoid all obstructions.
Notice that the ATR-72 has short, straight wings. It looks like from the video that the left prop is spinning/windmilling - meaning it is not feathered and is creating enormous drag. Much of the lift on the left wing is going to be provided by the prop wash from that engine, and with the engine failed and not feathered that wing will stall and promptly roll the plane onto the left side.
I agree, avoiding those buildings is a skilled bit of piloting. I can see the maneuver to sacrifice speed for altitude to clear those buildings causing the stall just after the “leapfrog” over the buildings.
Reiterating my other comment - any commercial plane must be able to continue to rotate and climb away at maximum takeoff weight, clearing any obstructions, with a single engine completely failed.
That’s a very interesting topic generally. A good comparison is the A330 and A340. The twin A330 has much more powerful engines, because it needs to be able to rotate and climb safely on only one. The quad A340 has less powerful engines because it would only need to rotate and climb on three - a less extreme scenario. The A330 also needs more rudder authority to counteract the yaw moment from having that much more power on one side.
Thanks for that–I stand corrected. I’m used to putting 70K lbs on a 4 engine aircraft just to fly circles around the flagpole, and the thought of having any engines fail at rotation is an unhappy thought to say the least.
The video quality and position makes it hard to tell if the flaps have been retracted or not…but I wonder–does that aircraft use engine-driven hydraulic pumps, or are they electrically driven? The 707 uses engine-driven pumps, and if one goes out, everything is that much slower, so if the ATR is the same, you’re down to one pump trying to keep the rudder locked to compensate for the lack of left-side thrust, as well as dropping flaps or feathering the prop…
It’s certainly fascinating from an engineering point of view, but horribly sad in terms of human cost and damage to the local community.
The ATR 72 has two hydraulic systems, Green and Blue, which between them supply services such as landing gear actuation, nosewheel steering, wing flaps, spoilers and the braking system. Each system is pressurised to a nominal 3,000 psi by an AC electric pump, which in turn is powered by a frequency-wild AC generator mounted on each propeller reduction gearbox.
While it’s an electric pump, the generator pushing it is engine-driven, so they would’ve lost one of the hydraulic systems once the left engine failed, unless the other generator could handle the load of both pumps. It’s entirely possible that one generator can push both pumps, but I would guess at a reduced rate. How much reduced, I haven’t the foggiest. I’d like to know what made the engine fail like it did, and I’m sure Pratt & Whitney would, too.
EDIT: I should’ve kept reading that crash report:
The Blue system is equipped with an auxiliary DC pump that runs automatically under certain conditions, including when the main system pump pressure falls below 1,500 psi, the landing gear is down and at least one engine is running. The frequency-wild generators drop off line when the propeller rpm falls below 70%. In operational terms, this means that when the propellers’ rpm are reduced prior to feathering following the aircraft’s arrival on stand, the Green and Blue system AC pumps will cease operating. This will cause the DC pump, powered from starter/generators on the high-speed engine spools, to cut in, thus maintaining pressure in the Blue system.
The wording isn’t very clear, although it appears the system has a fallback DC pump that will boost pressure, if needed.
At the very least, we’ll know much much more when the black box information is sorted out.
Investigators say the pilots had dual engine failure, they received five stall warnings, issued mayday to the tower. Poor sods knew they were going in.
The right engine first entered a state called “auto-feather”, in which it reduced thrust to the propeller, Thomas Wang, managing director of the council, said.
The flight crew then reduced acceleration on the left engine and then attempted to restart it, but it did not gain enough thrust. He did not give a reason.
“The first engine experienced a problem 37 seconds after take-off at 1,200 feet,” Wang said. He said the pilot had announced a “flameout”, which can occur when fuel supply to an engine is interrupted or when there is faulty combustion, but there had not been one.
“The flight crew stepped on the accelerator of engine 2 (righthand side) … The engine was still operating, but neither engine produced power.”
I think something is getting lost in translation in these quotes somewhere.
Sounds a bit like the BA 777 (Aside: I flew out of LHR the day after, the pilot on our plane pointed the 777 out to us)
The beeb is reporting that the airline’s pilots are undergoing 4 days of training, testing and evaluation in the wake of the incident.
The beeb reports that the pilots may have shut one engine down after “losing power” on the other. The lost power engine may it appears have simply been moved into idle mode, and the suggestion is that the pilots erroneously shut down the other (power-delivering) engine by mistake.
They praised the pilot for avoiding the buildings.
When I read the ‘wrong engine’ report, I remembered Kegworth as well.
In which case being dead might be a kinder fate for the pilots. Poor Hunt and McClelland were first feted and then the easy scapegoats in the Kegworth crash.
I remember Kegworth well. Grew up 10 miles away. And yeah, the pilots got scapegoated. It’s never just one thing that goes wrong, regardless of the mistakes they did make.
One of them got some compensation for unfair dismissal I think.
