Roger Roger
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When i go to recurrent I’ll have to play around with some engine failures with inop rudder boost just to see what it’s like.
Emirates near disaster on takeoff
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jrh
Well-Known Member
I'm a training captain for 500-series Citations at an operator who does lots of training and checking in the actual airplane. I've done quite a few simulated engine failures on climbout by pulling a throttle to idle immediately after gear retraction. So at about Vr+20 or Vr+30 probably.
The actual airplane is considerably easier to fly than in the sim. The sim requires mashing the rudder to the floor and holding it there. The actual airplane requires very little rudder pressure compared to pretty much any piston twin or small turboprop like a King Air. I couldn't tell you specifically how many pounds of pressure it needs, but I brief new pilots that it will probably be easier than whatever twin they've previously flown, and after doing it, nobody has disagreed.
The actual airplane is considerably easier to fly than in the sim. The sim requires mashing the rudder to the floor and holding it there. The actual airplane requires very little rudder pressure compared to pretty much any piston twin or small turboprop like a King Air. I couldn't tell you specifically how many pounds of pressure it needs, but I brief new pilots that it will probably be easier than whatever twin they've previously flown, and after doing it, nobody has disagreed.
Yea I would say that 20-30kts is quite significant and really shouldn't be used to draw a comparison. Also the performance setup for the sim profile is fined tuned to be challenging yet successful with proper technique.
I'm curious have you tried the same technique in the simulator and how did it behave?
$180K for two years? Two years? ATC sounded like European expats.
I know they are getting PAID!!!!!!!
NovemberEcho
Dergs favorite member
Dubai? It’s almost all Americans/Brits/South Africans and Aussies.
T/O w/FSII
Well-Known Member
jrh
Well-Known Member
No. There's no specific guidance prohibiting it as far as I know, but I don't personally feel like the risk is worth the reward. Kind of like practicing a high speed abort or something.
I do get somewhat more aggressive at altitude in the practice area. We'll slow to Vr in a takeoff configuration, apply max climb power, then simulate a failure. Same as close to the ground, it definitely takes rudder but it's also definitely easier than the sim and most piston twins.
jrh
Well-Known Member
The sims I've used at FlightSafety, representing the V and Encore, both require the rudder to be all the way to the stop, or very nearly so, to maintain directional control at V2. The best advice I got during my initial training was to not try to "fly" it, just mash the rudder to the stop and only back off if it became obvious I needed less.
I should add, I simulate failures at about V2+10 or V2+20, but it's not a big deal to slow to V2 after the failure. I still consider the actual airplane to be way easier to fly than the sim.
typhoonpilot
Well-Known Member
B777 has thrust assymetry compensation, which works some to most of the time (except in the simulator
).The thrust asymmetry compensation (TAC) system significantly reduces
uncommanded flight path changes associated with an engine failure. TAC
continually monitors engine data to determine the thrust level from each engine.
If the thrust level on one engine differs by 10 percent or more from the other
engine, TAC automatically adds rudder to minimize yaw.
Before liftoff, TAC does not fully compensate for the failed engine so the pilot can
recognize engine failure through roll/yaw cues. These roll/yaw cues are greatly
reduced when compared to an airplane operating without TAC. After liftoff, TAC
attempts to fully compensate for the failed engine.
The amount of rudder used is proportional to the engine thrust difference. Rudder
movement is back–driven through the rudder pedals and displayed on the rudder
trim indicator. Following engine failure, the pilot can trim the airplane using
additional rudder trim, control wheel input, aileron trim, or autopilot engagement.
TAC is available except:
• when airspeed is below 70 knots on the ground, or
• when reverse thrust is applied, or
• when automatically disengaged due to system malfunction or loss of
engine thrust data.
TAC automatically disengages if engine thrust data is lost. TAC may also
disengage following severe engine damage or surge if it is unable to determine an
accurate thrust level. TAC may still cause some rudder deflection in the
appropriate direction just before automatically disengaging.
TAC can be manually overridden by making manual rudder pedal inputs. TAC is
only available in the normal flight control mode. To manually disarm TAC, push
the THRUST ASYM COMP switch on the overhead panel. If TAC is
automatically or manually disconnected, the EICAS advisory message THRUST
ASYM COMP displays.
typhoonpilot
Well-Known Member
What was the question?
Basically at the supposed speed this flight was at on the ground would a 777 start flying?
Boris Badenov
Fortis Leader
(Without anyone doing anything rash, like pulling back on the yoke. At all.)
milleR
Well-Known Member
I was curious if, when trimmed and configured properly for takeoff, a 777 would be generating enough lift at Vr+50-70 knots to get airborne without any control input from the crew.
typhoonpilot
Well-Known Member
To be perfectly honest that is not something I have ever tried in a simulator. I would say, at some point, yes it probably would but I ever never tried to find that point.
I really think that the data that is being reported is wrong. Normal rotation speed at their approximate takeoff weight would be 175 KIAS. That is the point the PM says "rotate". A slow rotation rate could easily see the airplane still on the ground at a speed 10-15 knots beyond that. That is not unusual. Tire limit speed is 204 knots on rotation (higher than the 226 knots on landing due to the pressure a tire encounters during rotation).
So the question I have is how accurate is this reported Fight Radar 24 (or whatever) data that is showing them still "on the ground" at some high speed? They could easily have had main wheel lift-off at 190 KIAS in a normal slow rotation and then been slowly climbing as the airspeed increased to the reported value.
My sources say this was not a big deal until it was reported in the press. Yes, it was a screw up and yes they did overspeed the flaps, but it was not as sensationally low to the ground as is being reported. Think about the possible calibration error of the Flight Radar 24 plot. If it was even just 50 or 100 feet off in calibration it changes the whole story.
milleR
Well-Known Member
Thank you, that all makes a lot of sense.
Could you expand on this? That seems contradictory to what I'd imagine the forces being on landing vs rotation. I'm assuming it's related to the difference between MTOW and MLW?
typhoonpilot
Well-Known Member
Good question. The first time I saw the difference I did a double take as well. Thinking about it further though, especially for large airplanes, the stress on the tire during the takeoff roll is going to be higher because 1) the airplane weighs more; 2) during initial rotation the pivot point is about the main wheels so they are getting compressed until they become airborne; and 3) the tire tends to be at a higher temperature during takeoff due to the heat build up during taxi. That heat build up can lead to tire failure in extreme circumstances (see Continental 603).
Some good articles on aircraft tires:
AERO - Exceeding Tire Speed Rating During Takeoff (boeing.com)
AC 20-97B CHG 1 (faa.gov)
milleR
Well-Known Member
Yeah that's kind of what I was thinking. I don't know the technical terms but the pivot point being the MLG at rotation at MTOW certainly has to add quite a bit of stress to the tires, I just would have thought the variability of impact forces depending on descent rate at touchdown would lead the engineers to a more conservative speed to protect tire integrity on landing. The temperature differential is certainly a logical factor as well, but this is way outside my area of expertise or experience so I really appreciate your input on this topic.
Edit to add- I imagine the fact the landing gear struts are already pretty compressed on rotation as opposed to being fully extended on landing must play a factor in loading force as well. I also suppose the risk analysis of blowing a tire on touchdown vs rotation would bias a restriction towards protecting the landing gear on takeoff. Great thought exercise, thank you
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fholbert
Mod's - Please don't edit my posts!
Thanks for so clearly explaining that.
GypsyPilot
Mohawk Town
Great question, thanks for asking it.