V1 in small twins

[youhavecontrol]

Smithers is over one set of mountains and Terrace is over two with not much in between.

Prince George is following shallow valleys and short mountain until you reach the plateau and you have Ft St James for a diversionary field if things go south plus the BC Rail right of way the whole way there.

It’s what I would have done.

Ah ok that makes sense.

[digits_]

I also remember that the mechanic wanted the engine unfeathered so the instructor started up the engine and it causes quite a bit of vibration in the aircraft while the propeller unfeathers. I am still not sure if that is something that is OK to do.

For what it's worth, I've also been asked to do that once. On a piston engine only of course, for turbines it's a bit more critical, depending on how hey are designed to work.

[pelmet]

I also remember that the mechanic wanted the engine unfeathered so the instructor started up the engine and it causes quite a bit of vibration in the aircraft while the propeller unfeathers. I am still not sure if that is something that is OK to do.

For what it's worth, I've also been asked to do that once. On a piston engine only of course, for turbines it's a bit more critical, depending on how hey are designed to work.

Some turbines, you can feather and unfeather while the engine is stopped using an electric pump. Bit off topic though.

[cncpc]

This lad has questions, if I'm honest. How did the AME test that the prop was balanced exactly and how did you verify that before you took-off? Did you do a run-up, feather check or governor check? You mentioned you immediately raised the gear... was that standard practice or did you modify your procedure given the suspicion of engine failure? Was it necessary to fly 165 miles back to base on one engine in the mountains? Was Smithers or Terrace not an option to get on the ground sooner?

The prop wasn't balanced exactly. It was a field repair at the side of a forestry road in the wilderness. That engine was run up after the repair, and again with the other one in a standard run up with all the power checks, but at run up RPM. It was a gravel road and a gravel pull off.

I raise the gear once there is insufficient runway ahead to land. This was a road with trees at the "departure end". There is a strip built near there since, but that road had been used as an airstrip for quite a few years. Balanced field length was not available. In those circumstances, as soon as the wheels are off and climb is established, I touch the brakes and raise the gear. I agree that was critical to the outcome.

I start every takeoff with a suspicion of engine failure. In this case, the engine didn't fail. It was shut down as a precaution against it coming out of the mount. Which it likely would have done if takeoff power had been maintained.

There was an ongoing discussion with the other aircraft that began right after the shutdown. The choices were influenced by the good performance on one engine and its ability to maintain 5500 with gauges in the green and normal cruise power. In some circumstances, it was possible to have started the shut down engine and using it at reduced power, but it would not have been usable on a restart because the other one had failed. Outs at Burns Lake, Ft. St. James, Vanderhoof, but as the flight progressed over or near to those points, it was never in difficulty and it was decided to go to Prince George, which was our home base. I considered a restart for the landing, but decided to not complicate things. No emergency was declared, but I did advise XS tower that I had one shut down. You can fly that route at 3500 feet. As IFly says, it's a plateau. It may be shorter to Smithers, but there is higher terrain in the way.

I've found that log book. I see it was Leo Creek on Takla Lake, and not Takla Landing. There is a 2500 foot bush strip there now, right where the road used to be, and they've cut down the trees at the northwest end. The log book says 120 miles S.E. but I see it's 140.

It was a normal takeoff until it wasn't. Then there was a new normal in which the aircraft performed as advertised. It took off, some things happened, and it landed without incident. I see it's still flying in Ontario.

[co-joe]

...

Same for a king air class kind of airplane. They are great performers. Why treat V1 as a life and death decision on a long runway? If you have 10 000 ft and something happens, even past v1, why not abort?

It just drives me bonkers. Discussing it with management or training pilots, even crew members always results in "But it's V1, it's the decision speed, you can't abort past V1!".

Thoughts? Am I missing something?

If you really want to calculate a legal and true V1 for King Airs, there's a program for the Ipad called I Preflight, it's put out by Aerodata, and you can do full balanced field, and net takeoff flight path calculations for King Airs, possibly even Navajo. The problem is, most of the aerodromes you operate King Airs out of wouldn't meet the requirements for ASDA, TODA, and TORA. If TC ever mandated balanced field for 703 most aerodromes would become illegal. Hell if TC ever ran the numbers for 704 ops, they'd realise there are lots of companies in Canada not playing by the rules.

Fact is, if you have an engine failure before Vr in a Beech, you might die, if you lose one after Vr and get airborne, you still might die...welcome to 703 aviation.

[goingnowherefast]

I've seen published balanced field and performance data for a King Air with V1, V2 and all. IIRC, it was in the back of a B200 Raisbeck supplement. The numbers weren't fantastic, 5000-7000', depending on conditions, flap setting, load, etc. Certainty didn't consider runway conditions, cause compact snow is the same as bare, dry pavement....

[rxl]

I think it would be better if pilots only used the term V1 for aircraft that actually have a published V1 speed(s). Otherwise, it can cause great confusion for newer pilots just learning about this stuff.

AGREED. How can you have a takeoff decision speed in an airplane that doesn’t have to guarantee the performance capability to continue that takeoff after the failure of the critical engine? What decision is there? The rocks or the trees I suppose.

[Alex335]

I raise the gear once there is insufficient runway ahead to land.

Why would you wait for insufficient runway in a twin? People do that in single usually.

On the piston twin I fly, and all the piston twin POH/AFM I’ve read called for gear up @ positive rate. Leaving the gear down just leaves you exposed, usually these aircraft won’t climb gear down near MTOW. Can always still land after the gear is retracted, but also gives you the option to climb if performance seems adequate. Just need to feather the prop and go, usually on normal take offs flaps are already up.

[Gino Under]

FWIW

Is it fair to say?
1) V1 is defined as the engine failure RECOGNITION speed.
2) V2 is defined as the MINIMUM SE flying speed.

If so, then...
The split can be significant between the two speeds. It's always nice to know what those two speeds are BEFORE you depart no matter what ME(L) aircraft you're flying. What you have to consider BEFORE any takeoff are the performance factors on the day in order to make the determination of those speeds. If you decide to make V1 your "go" speed, then V2 becomes your minimum safe flying speed to get you to the MSA and comply with the performance certification standards to at least 1500 feet AAE. When considering the environmental conditions at the time of your takeoff, it's wise to consider that the battle between V1 and achieving V2 could be a real struggle.
It is usually recommended (try not to think of it as mandatory) that a takeoff be discontinued should an engine fail at or below V1. There are always variables to consider. Not all takeoffs are the same nor do they necessarily happen on runways with the same declared distances and elevations. So remember, takeoffs will always give you a variation on what's considered normal so be aware that not all one-size-fits-all applies when making decisions. You could find yourself in a situation where "go" is the better decision. What then? The suspicion you should have is when an operator in its SOP tells you in all cases to discontinue a takeoff if an engine fails at V1. Such writings simply remove the reject decision from the PIC who will ultimately 'wear it' if it all turns to puppy mush. I can assure you, authors who write those kinds of SOPs will be nowhere to be found when it comes time to clean up the mess.

https://aviation-safety.net/database/re ... 19920730-0

I could keep my Navajo/King Air/CRJ/B777 on the runway beyond V1 if I decide to "go" with sufficient runway remaining, achieve V2 plus a few knots for the family, rotate, then use the initial climb to reduce my speed to V2 plus a safety factor for maneuvering (usually 10 knots).
I'd say, this is a general consensus based on the preceding posts from those much smarter than me.

An excellent presentation on aircraft performance (FAR Part 25) is provided by APG. Our regulations closely, if not exactly, adhere to the FAA's Part 25 requirements anyway.

https://www.youtube.com/watch?v=iEULv-3LCEo&t=24s

cheers,
Gino Under

[jakeandelwood]

This discussion is why Cessna designed the Skymaster. I've never flown one but I imagine as far as light twins go it performs fairly well on one engine, can anyone comment on that who has flown one?

[PanEuropean]

Let's start with an example of a navajo. Accelerate stop somewhere around 3000 ft, single engine stake off distance probably around the same. This airplane is now taking off from a 10000 ft runway, with a V1 calculated for a 3000 ft runway. You have 7000 ft of extra runway that is not taken into account. Let's say its engine catches fire past v1, would it not be much safer to just abort in the remaining extra 7000 ft?...

Am I missing something?

One thing I think you are missing is whether or not it would even be possible to align the aircraft with the remaining runway - even if there is 7,000 feet of it ahead of you - if your rejected takeoff is due to asymmetric power.

I spent many years training twin turboprop pilots in a FlightSafety simulator. One thing that became very clear to me was that if the pilots were given an engine failure at or immediately after rotation, and they had not been briefed ahead of time that they would be getting an engine failure, the aircraft would swerve significantly off runway heading. Proficient pilots would usually be able to recover from the heading loss and re-establish themselves on runway heading, but by the time they did that the aircraft was significantly displaced laterally from the runway. The likelihood of the pilots being able to maneuver the aircraft back over top of the runway and land on it - even if there was 7,000 feet remaining - was minimal.

If a high-speed reject decision (a reject on the ground above V1 but below Vr) was made due to a problem other than a power asymmetry, obviously, the remaining 7,000 feet would be sufficient to stop the aircraft.

For practical purposes, though, the difference between V1 and Vr in twin engine aircraft weighing 12,500 pounds or less is pretty small - perhaps 5 to 7 knots, and that V1 to Vr gap lasts one second or less. A more pragmatic approach when runway distance is not limiting might be to brief that "if we have a problem on the ground, we stay on the ground, and if we have a problem in the air, we stay in the air".

This is where the difference comes in from the "checklist only" type of pilots vs the common sense pilots. It shouldn't even be a deep thought if you're flying a small twin from a long ass runway, screw V1; with 5000 in front put the thing back down. V1and VR will be within a few knots so you're likely airborne with 6-7000' left....even at 2-400' AGL you could get it back down and stopped before the end

Maynard, for the reasons given in my post above, I disagree with you. You might think you can put it back down on the runway, but my 5,000 hours + of training pilots in the simulator (with an average of at least one engine failure at takeoff every 2 hours of training) tells me that the odds are against you getting it back down on the asphalt. On the airport property, yes, but the runway - not likely.

[digits_]

Let's start with an example of a navajo. Accelerate stop somewhere around 3000 ft, single engine stake off distance probably around the same. This airplane is now taking off from a 10000 ft runway, with a V1 calculated for a 3000 ft runway. You have 7000 ft of extra runway that is not taken into account. Let's say its engine catches fire past v1, would it not be much safer to just abort in the remaining extra 7000 ft?...

Am I missing something?

One thing I think you are missing is whether or not it would even be possible to align the aircraft with the remaining runway - even if there is 7,000 feet of it ahead of you - if your rejected takeoff is due to asymmetric power.

If you're unable to maintain directional control, it's probably an even worse idea to go flying...

I spent many years training twin turboprop pilots in a FlightSafety simulator. One thing that became very clear to me was that if the pilots were given an engine failure at or immediately after rotation, and they had not been briefed ahead of time that they would be getting an engine failure, the aircraft would swerve significantly off runway heading.

Well yes, it's a sim. You're missing a lot of information. While it may simulate some G forces, it doesn't do it exactly like you would feel it in a real airplane.

[PanEuropean]

If you're unable to maintain directional control, it's probably an even worse idea to go flying...

Hello Digits:

I didn't state that pilots cannot maintain directional control - in almost all cases, once a pilot becomes proficient at handling engine failures during the takeoff phase of flight (max power on one engine, the other one failed), directional control in the sense of recovery to runway heading is accomplished quite quickly, usually within about 3 or 4 seconds. The problem is that during the first few seconds that it takes for the pilot to recognize & react to the asymmetry, the aircraft yaws significantly off runway heading. Once the pilot has reacted appropriately and re-established runway heading, the aircraft is then laterally displaced from the runway, flying parallel to the runway.

The amount of lateral displacement is not big enough to create any safety issues if the aircraft continues to climb away, but it is big enough to make it very problematic if the pilot attempts to put the aircraft back down on the remaining runway. The remaining runway won't be "under the nose", it will be off to the left or right of the aircraft, thus requiring a "S" turn to get back over the runway and then touch down on runway heading.

Well yes, it's a sim. You're missing a lot of information. While it may simulate some G forces, it doesn't do it exactly like you would feel it in a real airplane.

I think you would agree that we don't fly the aircraft by "feel" we fly it by reference to instruments or visual reference to the world outside. During sim training, most engine failures at takeoff are presented in a "worst possible" visual environment - weather at takeoff minima and a night-time visual scene. That keeps the pilot's head "inside", on instruments.

I've had two real-life engine failures in my career - one at takeoff, and one (very sudden & violent, accompanied by other airframe damage) in cruise. Two engine failures in real life does not make me an expert on engine failures, but I do recall both of them clearly, and in each case, the aircraft behaved in much the same way as the simulator did. Hence I think that large full motion simulators that are TC certified are reasonable proxies for the aircraft.

[digits_]

If you're unable to maintain directional control, it's probably an even worse idea to go flying...

Hello Digits:

I didn't state that pilots cannot maintain directional control - in almost all cases, once a pilot becomes proficient at handling engine failures during the takeoff phase of flight (max power on one engine, the other one failed), directional control in the sense of recovery to runway heading is accomplished quite quickly, usually within about 3 or 4 seconds. The problem is that during the first few seconds that it takes for the pilot to recognize & react to the asymmetry, the aircraft yaws significantly off runway heading. Once the pilot has reacted appropriately and re-established runway heading, the aircraft is then laterally displaced from the runway, flying parallel to the runway.

The amount of lateral displacement is not big enough to create any safety issues if the aircraft continues to climb away, but it is big enough to make it very problematic if the pilot attempts to put the aircraft back down on the remaining runway. The remaining runway won't be "under the nose", it will be off to the left or right of the aircraft, thus requiring a "S" turn to get back over the runway and then touch down on runway heading.

I was talking about aborting when you are still on the runway, must have misinterpreted your post. I agree that landing again just after take off would be quite challenging.

Well yes, it's a sim. You're missing a lot of information. While it may simulate some G forces, it doesn't do it exactly like you would feel it in a real airplane.

I think you would agree that we don't fly the aircraft by "feel" we fly it by reference to instruments or visual reference to the world outside. During sim training, most engine failures at takeoff are presented in a "worst possible" visual environment - weather at takeoff minima and a night-time visual scene. That keeps the pilot's head "inside", on instruments.

I've had two real-life engine failures in my career - one at takeoff, and one (very sudden & violent, accompanied by other airframe damage) in cruise. Two engine failures in real life does not make me an expert on engine failures, but I do recall both of them clearly, and in each case, the aircraft behaved in much the same way as the simulator did. Hence I think that large full motion simulators that are TC certified are reasonable proxies for the aircraft.

If you are flying in IMC, then yes, the plane behaves pretty much like in a simulator. But on the ground, using visual references, the model is quite a bit off. You very much control the plane by feel a that point. How do you know how much you brake during regular taxi? You feel it, you want to make sure you don't jerk the plane around for pax comfort. Same with rudder application during initial take off roll. You need very small corrections. They are so small that you can't see that in your instruments, you use the feel on your feet to determine how far you can go to keep the plane on the center line. When one engine craps out, and you need more aggressive inputs, you'll still rely on that feel. Not so much for the initial application (full deflection), but more for the subsequent small corrections to keep it on the centerline.

A high speed reject in the sim doesn't feel anything like the real thing, at least in small planes. It's way too sensitive.

During ground operations, you are very much looking outside and relying on what you see. If you abort on instruments in a small plane, you'll have a very bad day. Even in low vis operations. Once you're airborne, you'll be using only the instruments in IMC, but during a reject that's not the case at all, and the sim experience breaks down quite a bit I find.

[iflyforpie]

How bad is your single engine control, and for how long?

Because heading does not equal track. If an engine failure caught you by surprise, your plane is going to be skidding along with the ball or brick not centred. Try turning the plane with rudder alone. It’s the same idea and not very effective.

For how long? A light twin/turboprop is only going 200-250 feet per second at typical climb speeds. Even if you were off course ten degrees (which would be probably 15 degrees for a heading or a strong cross wind on the live engine side) for 8-10 seconds (count it.. one thousand one.. one thousand two....)... you’re only about 350 feet off centreline or 250-300 feet from runway edge after going a distance of about 2000 feet. You still have another 2000 feet to align yourself with the runway and 3000 more to land and stop.

Anyone should be able to do this especially considering yaw will no longer be a factor as you bring power back.

The original scenario was fire, not failure, so yaw shouldn’t even be a factor. I’d only ever do this for controllability issues or if I felt that the fire was severe enough that structural failure was imminent. And then, I don’t care if I wind up on the runway.

[Gino Under]

Since Vmcg and Vmca occur before V2, going airborne beyond V1 is rarely a control issue. I certainly don’t advocate going airborne then trying to land straight ahead unless “in the heat of battle” it’s your best option.

When simulation accurately replicates the actual flight characteristics of an aeroplane into the 90 percentile (which is a Part 61 certification requirement) it’s of little value to blow off flight simulation as “not being like the real aircraft”. Aircraft manufacturers provide the sim manufacturer with the “certified” performance package to make it so. Sorry, but this is simply one of those ‘old wives tales’ of convenience for pilots who need an excuse for their sloppiness in a sim.

I’ve found that students who have a tendency to wander off the runway centerline with an engine failure usually haven’t got the correct hands and feet inputs properly coordinated. In other words, the ailerons may be positioned so that they favour a right or left bank with the ‘ball’ centered producing a coordinated turn. By adding or reducing rudder input followed by an aileron correction the aircraft can be trimmed wings level on a steady heading and flown back to the desired runway heading.

Cheers
Gino Under

[digits_]

When simulation accurately replicates the actual flight characteristics of an aeroplane into the 90 percentile (which is a Part 61 certification requirement) it’s of little value to blow off flight simulation as “not being like the real aircraft”. Aircraft manufacturers provide the sim manufacturer with the “certified” performance package to make it so. Sorry, but this is simply one of those ‘old wives tales’ of convenience for pilots who need an excuse for their sloppiness in a sim.

Are you saying that rejected take offs are accurately represented with all forces in a sim? I'm not talking about force feedback on the control columns, I'm talking about actual forces on the occupants.

If that's all part of the 90% accuracy, then I'd say those last 10% that are missing, are really important to get ground operations simulated properly.

Where does the sloppiness in a sim come from? Why do experienced crew need to "adjust" to the sim a few minutes during recurrency? Because the first things you usally do once moving, is ground operations (taxi, turns, braking). There is something missing in the sim to simulate this accurately. The most common example would probably be a brake check. Almost nobody slams the brakes in a real airplane, yet the 3 different sim models I've experienced were always ridiculously sensitive to that. Same with turns.

Once you're flying, and in low g stable regimes, it's very realistic. Once you should be starting to experience more g, the simulation starts to fall apart a bit.

[pelmet]

Since Vmcg and Vmca occur before V1, going airborne beyond V1 is rarely a control issue.

Where does it say that Vmca must occur before V1. I don't believe that is correct.

When simulation accurately replicates the actual flight characteristics of an aeroplane into the 90 percentile (which is a Part 61 certification requirement) it’s of little value to blow off flight simulation as “not being like the real aircraft”. Aircraft manufacturers provide the sim manufacturer with the “certified” performance package to make it so. Sorry, but this is simply one of those ‘old wives tales’ of convenience for pilots who need an excuse for their sloppiness in a sim.

I can guarantee you that there are sims that are significantly different in handing than the airplane. I have done type ratings in 7 sims. The more modern ones have become closer to reality, although can still be touchy in pitch. Some of the older ones are extremely sensitive. A couple of sims for aircraft types were extremely sensitive(One of them was an additional sim that I flew for an interview years ago which was a Dash-8) where if one looked away more than momentarily while manually flying, the aircraft was moving fairly quickly toward a significant bank angle.

It was also interesting to note that different sims for the same type can handle differently. On one type, an V1 cut required full aileron and rudder to prevent a crash while a different sim required much less input.

[Gino Under]

pelmet

It doesn’t say that anywhere. Thanks for catching that. My focus was on min control speeds relative to V2. I’ve edited my previous post accordingly. Thanks.

I’d say your interview DH8 could have used some control tuning.

We seem to agree for the most part, there are some sloppy sims out there but flight simulation has its limitations. For Level C and D simulation though, at the risk of sounding smug, there are 2 realities that will never be overcome. “G” loading and airflow. So no, 100% aircraft handling fidelity is not possible. That said, however, within the remaining <10% fidelity, the remaining ‘sloppiness’ is primarily subjective tuning. Everything else is the data collected during actual aircraft certification flight testing that puts the device in that 90 percentile.

Why do specific types (i.e., B737NG) handle differently from location to location?
Because an NG sim sitting in Montreal compared to an NG sim sitting in Dallas or Amsterdam may have been or were likely tuned and evaluated by the different subjective opinions of their evaluators. It’s as simple as that. The software data packages are the same for all 3.

Every authority who certifies synthetic devices are fully aware of these limitations. If you regularly use a FFS that you think is unnecessarily sloppy, snag it so it can be re-tuned by the training center technicians.
You never hear students say in a sim that the light turbulence we’re in seems too light compared to the real thing. Or, the sound generated by that compressor stall should be quieter.

Gino

[pelmet]

Let's start with an example of a navajo. Accelerate stop somewhere around 3000 ft, single engine stake off distance probably around the same. This airplane is now taking off from a 10000 ft runway, with a V1 calculated for a 3000 ft runway. You have 7000 ft of extra runway that is not taken into account. Let's say its engine catches fire past v1, would it not be much safer to just abort in the remaining extra 7000 ft? On such runways, why would V1 ever be lower than Vr?

Same for a king air class kind of airplane. They are great performers. Why treat V1 as a life and death decision on a long runway? If you have 10 000 ft and something happens, even past v1, why not abort?

It just drives me bonkers. Discussing it with management or training pilots, even crew members always results in "But it's V1, it's the decision speed, you can't abort past V1!".

Thoughts? Am I missing something?

You have brought up some good points. Of course anyone can abort past V1 instead of continuing but virtually all of aviation has moved to the 'You must continue idea" which overall is for good reasons due to a fair number of accidents from pilots unnecessarily aborting after V1. But you are correct when thinking that under some situations, if you abort beyond V1, you will be able to stop within the confines of the runway.

It is kind of like de-icing. Plenty of pilots have taken off with frozen contamination on their wings. I would bet that most of the people posting on this forum have, although some perhaps some only unknowingly. The problem was that some pilots ended up crashing because they took off with more than the aircraft could handle, perhaps due to being in an aircraft particularly sensitive to a small amount of contamination and they were not aware of this contamination or or they used very poor judgement and really had a lot of contamination on a less sensitive aircraft. So things became more strict and now one must de-ice even if there is a tiny amount of contamination, such as the time I saw an aircraft de-ice with a brief spray on the winglet. The idea......if one always de-ices for frozen contamination, even if it is just a lit bit as it will eliminate the occasional cases where there would have been an accident.

Same with V1.....one must always continue, even if it is obvious that the aircraft can be stopped. Why? Because some pilots thought they could stop, tried, and then discovered that they could not stop due to things like blown tires, heavy weights, reduced braking action, etc. If no pilots ever rejects above V1, then the occasional fatal accident won't be mixed in with the successful outcomes.

Unfortunately, things can get dicey on certain aircraft when they are at their 'WAT'(or performance) limits and a failure happens at the most critical time or some other kind of failure happens such as gear won't retract, prop won't feather, etc. The certification authorities don't take many rare scenarios into consideration. There can be rare occasions where it would have been better to reject above V1. Black swan incidents happen where outside the box actions have saved the day.

But the bottom line is.....you should not reject the takeoff after V1 unless there is some critical reason such as the aircraft is incapable of flight.

An interesting accident that encompasses some of the discussion that has taken place on this thread can be found in the link below to an accident report.....

https://reports.aviation-safety.net/199 ... G-OJEM.pdf

It should be thought of as an extreme situation.

[pelmet]

Adding a bit more to the V1 and remaining runway distance. I flew a large twin turboprop for a while and we always used the same balanced field length numbers for takeoff at a given weight(and for landing). I still have some of the numbers in my head like 90, 98, 122 for one particular landing weight we regularly landed at. For a max weight takeoff, it was 109, 115, 127. That would give a certain balanced Field length. These takeoff numbers for V1, Vr, and V2 were used a lot at our main base with its fairly long runway. But if we were to go to JFK airport and takeoff under the same weight, altitude, and temperature condition on its 14,511' runway, we would use the same takeoff speeds. Obviously, if one could stop within the confines of a runway less than ten thousand feet long, one could stop on JFK's 31L at a speed well above V1.

[rxl]

It has been my experience that people get themselves into trouble with directional control with an engine failure at V1 in the simulator (assuming V1=Vr which is at least 95% of the time in our operation) from using too high a rotation rate and also trying to use ailerons to help control the resultant adverse yaw. A MAXIMUM rotation rate of 3 degrees per second is recommended for all takeoffs in the types that I am most familiar with. Even in a RVR600 takeoff scenario, a slower (normal) rotation rate yields an opportunity to nail the yaw with visual cues from outside reference like runway centre-line lighting before that reference is lost. Much easier to stop that yaw using visual cues. An engine failure on takeoff where Vr>V1 is easier to handle because you have the visual reference to control yaw available. Then on rotation pitch control can be the main focus.