Not true. On a 747 its between 114 and 132kts depending on T.O. power setting. Granted, that considers a critical engine failure which would be farthest from centerline, but I would suspect that on those hi-powered, big twins, Vmcg could be a pretty high number. You would have to talk to a 757/767/777 driver to confirm that for you.

Ailerons dont come into play for Vmcg. Anything more than 2 degrees (on a Boeing) effectively nullifies your T.O. data.

 

Like I said, "Generally speaking". I also said that depending on the aircraft. My post was meant to be a general post...not a thats not how the 73/75/74 works. Of course a 747 will have a higher speed. The more non-certerline thrust that is generated the higher the speed. I agree. But to quote the 72 Flight Ops Manual, "Eighty knots is the defined point that separates the Low Speed Regime from the High Speed Regime. In the Low Speed regime a takeoff may be rejected for a number of malfunctions. In the High Speed Regime the number of malfunctions that require a reject are dramatically reduced. The Captain must remain "go oriented" in the High Speed regime."

With that said, in a high speed regime it is safer to continue the takeoff than it reject. Below 80 kts (accelerate-stop oriented) it is safer to keep your hands on the tiller for reject purposes.

The bottom line is that above 80 kts you have increased control and reduced runway length/safety margin. Therefore, it is safer to take your hands off the tiller above 80kts than it is to take your hands off below 80kts. It is also safe to assume that if you are using a 80kts call, 80 kts is probably closing on Vmcg. On the C-130J, we use 70kts as the speed to define high speed regime. So for certain malfunctions you would reject prior to 80kts and for others you would not. For malfunctions that are considered critical to safe flight, you would reject in the high speed regime (80kts - V1) b/c it is considered safer to accept the high speed reject on reduced runway margins than it would be to take it airborne.

The original question asked, "He insists that the tiller is used for the first 80 kts on the takeoff roll because there is no rudder steering tied into the nose gear and it's not effective until 80 kts and that's the whole point of the 80 kts callout."

My original attempt to answer the post was probably to vague and general. Each aircraft is going to be different, but the standard operation procedures regarding take-off/reject decisions will be similar.

BTW, does the 73/74/74/76 use a 80kt call out?

 

The Capt guards the tiller until the 80kt call at our airline in the 747 - if you lose the critical engine you'll need the tiller to keep it on the concrete up to around that point. It's also a check for power set/throttle hold as previously mentioned.

The flying pilot has the rudder, the FO will hold nose down on the yoke if the Capt's flying. If it's the Capt's leg they'll move their hand from the tiller to yoke at 80 kts.

HTH
Spongebob.

 

In the Hawker there is absolutely no nosewheel steering in the rudder pedals. The pilot flying keeps one hand on the tiller and the other on the throttles until 80 kts. The non flying pilot holds the controls with crosswind correction up to that point. It takes some getting used to, and requires good crew coordination.

 

Tiller? I wish I still had one of those... 100% steering through the rudder pedals in the Slowtation.

 

HAHAHA......priceless

 

In the airplanes I flew (KC-135, 727, 737, 757, 767, MD-80, Airbus among them) NONE recommended that you use the tiller for control on the runway. Authority on the rudder pedals was 8deg either side (for some reason I remembered it as 12deg) and with the tiller it was 78deg. You can scrub a set of tires very quickly using the tiller and it MAY not be very effective in controlling the direction of the aircraft as proved by the 737 crash at LGA back in the 90s. As for the yoke, it is recommended that you keep slight forward pressure on it to ensure good nosewheel contact as speed increases on takeoff.

The 80kt call is many things... as noted, an airspeed check, the point at which one changes from low speed abort criteria (just about anything including caution lights) to high speed abort (fire, eng failure, perception the airplane will not fly) and this will include verification that the engines are fine, autothrottles/autothrust (if available) is operating correctly. Busy time...

It may vary with aircraft but I have never been in a community or on an airplane where the tiller was used as anything other than for taxiing where small radius turns were required.

 

+1.

And if I may add, the Tower 747 accident at JFK.

 

ERAUdude:

Once the aircraft is lined up with the runway centerline, steering is done with the rudder pedals. It may vary a degree or two with different aircraft types but on most Boeing transport category aircraft, there is 7 degrees of nosewheel steering either side of centerline with the rudder pedals. That's more than enough to keep the aircraft on the centerline.

In initial sim training, we teach do NOT use the tiller to steer the aircraft on the runway. Period !! Don't even touch the tiller. Period !The same holds on landing, where it is even more critical.

I'm aware of a transition pilot who used to grab the tiller on a rejected take-off. After about the third time (being told not to touch the tiller on the runway), the instructor rapped his hands and knucles so hard, he had welts on them. Didn't make it through training but I've been told drives a nice bread truck now.

The "80 knot" call has many purposes. It's a cross-check of the airspeed indications, a validation that the autothrottles have entered the " hold mode", entering the "high speed abort" criteria, and depending on the aircraft, numerous system functions begin at 80 knots.

Hope this helps.

G'Day Mates

 

Whoa phantom flyer...4 month old thread.