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Pelican’s Perch – Where Are The Eyes?
By John
Deakin, Columnist
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In my last column we covered where I think pilots of
light piston aircraft should be looking during takeoff and the initial-climb
phases of flight, say to 1,000 feet AGL.
In my opinion, virtually all attention should be outside
the cockpit unless there are no outside references available to keep the
airplane upright, climbing, and roughly on track.
There is almost never a need for precise airspeed
(certainly not Vx or Vy), continuing on the runway
heading will suffice, and unless there are some really low restrictions,
altitude doesn't matter, either.
There are always those who want maximum precision in
everything they do, and bless them. But in this case, maximum precision comes
at the expense of safety. You need to be "eyes outside" in these
aircraft. For the most part, GA aircraft operate in a target-rich environment, with
lots of opportunity for close encounters of the wrong kind.
Even with the new generation of glass cockpits (as with
the Garmin G1000), I would not modify my suggestions. There's nothing there
that is critical in that first 1,000 feet.
Touching briefly on flight after the departure, including
cruise, I see far too many pilots playing with the fancy modern stuff, as if
maximizing the capabilities. Wrong approach, I think.
I'm not fond of punching in a full route, because I'll
never fly it anyway. Between vectors, weather, changes by ATC and frequent
Direct clearances, most of that button-pushing is going to be wasted. Punch in
the absolute minimum "stuff" you need to get the job done, and in some cases, that may be
"departure. direct. destination." Learn to use the absolute minimum
of keystrokes to do what is needed, then leave things alone. Just because you
can do something with the fancy avionics doesn't mean you should do it.
I'd also point out that the more buttons you push, the
more likely you'll make a mistake that may just confuse the daylights out of
you in a later, high-workload, high-stress situation. The KISS principle is
appropriate here.
So much for review; let's move on.
Large Aircraft With Two Pilots
It would be really easy to just include the big iron and
say, "Airplanes are airplanes; they all fly the same."
To tell the the truth, I was a little bit surprised at how
much different my advice is when flying the Gulfstream IV or any
high-performance jet. Until I started thinking about writing this column, I
didn't realize how much more "heads-down" I am and how much more
complicated it gets.
Let's explore this a bit, and see how much of the
difference is due to the nature of the airplanes, and how much is due to the environment
in which we operate them.
The
Takeoff Roll
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Douglas
DC-10 |
With a piston aircraft, the proper technique is to place
the aircraft in the liftoff attitude as the speed increases. This is not a "rotation"; it is
simply a few degrees nose-high, just enough to fly off at some point safely above
the stall speed. The actual lift-off airspeed is not critical. If mishandled,
the airplane can be forced into the air well below the stall speed, because of
the prop(s) blowing air over the wings.
That doesn't work very well with jets. The liftoff attitude
with most jets is much greater -- somewhere around 10 degrees due to the higher
wing-loading, high-lift devices, and swept wings. If we were to place the
aircraft in this attitude too soon, the drag would increase greatly, and in
some of the older jets, the high drag will even prevent further acceleration.
Since no air is being blown over the wings, there is no
additional lift available. Lift can only come from airspeed and angle of attack
in the jet. For these and other reasons, you will notice that jet aircraft
accelerate in the level attitude (minimum drag), then rotate sharply to fly,
lifting off as they pass through about 10-degrees pitch, on the way to 15- to
25-degrees pitch.
Certification rules require the airspeed to stabilize in
the climb at V2 with an engine out, or about V2+10 with
all engines. Very early in the jet age, it was obvious that conditions were so
variable, and acceleration so hard to judge, that a new speed was invented
called Vr or rotation speed. The theory here is that if a pilot
starts the nose up at Vr, and rotates the aircraft at roughly two
degrees per second ("rotation" refers to change about the lateral
axis), then the aircraft will stabilize at V2 (engine out) or V2+10
(all engines). There is usually 10 to 20 knots difference between Vr
and V2.
Jet takeoffs are based on three critical speeds. V1
is the "go or no-go" speed, and must be some above minimum control
speed with an engine out. Vr must provide the proper timing to go
from level to the attitude at V2 or V2+10, and V2 must
provide the certification performance. Each speed can and does affect the
others, so rather complex charts (or computers) are used to figure all this out
in advance of every takeoff, and most of the time there are many options.
With small, light jets (Citation, Lear, Eclipse), the
range of weights is rather small, and these speeds don't change much. Many will
just use "canned" speeds for most conditions. With the 747, V1
can range from about 115 (very light) to 160 knots when heavy. Guessing here
will not suffice!
Key here is the fact that the takeoff roll and rotation is
absolutely mechanical and there is no "feel" or airmanship involved.
The crew sets the thrust and watches the fun. Once the airplane becomes
airborne, then pilots revert to feel and airmanship to regulate airspeed,
attitude, and pitch rate.
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Boeing
747 |
How critical is all this? In a Citation, operating off a
10,000-foot runway, it's not critical at all, and pilots could probably just
wing it. In a loaded 747, liftoff occurs with the aircraft eating up runway at
a rate of 300 feet every second, and runway length is usually critical, so it's
very important to be on the numbers.
V1 is not
as critical, in my opinion, as most pilots seem to think. Don't get me wrong: A
high-speed abort right at V1 on a critical runway is a terrifying
thing, but continuing the takeoff from well below V1 is almost a
non-event, with plenty of real margin. For this reason, the concept of a
"soft V1" has finally come into common use and pilots are
slowly coming around to using lower V1 speeds, when available.
My personal preference is to use the lowest permissible V1
on all takeoffs, and treat it
as a soft V1. The briefing is, "Up to 80 knots, we'll abort for
almost anything, from 80 knots to V1 we'll abort only for an item
that makes the aircraft unflyable, like uncommanded reverse, engine failure,
spoiler extension, etc. Approaching V1, I will take my hand off the
thrust levers, and that is the signal that we'll take any problem into the
air."
A lot of people in a lot of airplanes have been killed by
high-speed aborts, but (with one exception I know of) none have been killed by
high-speed "gos." (The exception is AA191, a DC-10 taking off from
Chicago O'Hare, May 25, 1979. That one is a case
study all by itself.)
We must
get away from the old and common attitude, "I'd rather slide off the end
of the runway than take an engine failure/fire into the air." Bad thinking!
What on earth has all this performance junk to do with
eyeballs? Hang on, there is a point here!
In the jets, someone in the cockpit has to pay pretty
careful attention to the airspeed indicators on the takeoff roll and, frankly,
both pilots are well-advised to do so. The PFN (Pilot Not Flying) usually
monitors and calls out key
speeds, often "Airspeed alive," "60 knots," "80 knots,
crosschecked," "V1," "Vr"
(usually called as "Rotation"), "V2," and
"Positive Rate."
If both airspeed indicators don't come alive at about the
same time, or if they don't both hit the benchmarks together, it's time to
abort before the speed is so high that the runway length becomes critical.
There are usually other things that should happen on the takeoff roll, too.
So, where are the eyes? In my case, when I'm the PF (Pilot
Flying), my attention is inside somewhat and outside a lot, with fairly quick
changes, and the runway is always in my peripheral vision when I'm inside (back
to the old T-6 in my previous column). At high speeds, a very small deviation
in heading will produce a runway excursion -- not normally a good thing -- and
I'm watching for other aircraft taxiing onto "my" runway.
It's very hard to put numbers on this, but perhaps 80%
outside, 20% inside. Heck, it might even be 50/50. The timing as to when we
look inside and back out is important, too. If I know I'm past 80, but well
before V1, my attention is mostly outside, because by then we've validated the
airspeed indications, and there's not much going on inside. As we approach V1,
I'll focus on the airspeed, and only peripherally on the runway. When I'm PNF,
I'm paying just a bit more attention inside but still keeping an eye on the
runway peripherally, to make sure the other pilot doesn't wander too much. That
80/20 is probably reversed for the PNF. It all happens very quickly, of course.
So, for the takeoff roll in the Bonanza, it's balls to the
wall, a quick check of ballpark fuel flow and engine-monitor readings very
early in the roll, and basically ignore the panel thereafter, until a few
hundred feet in the air. With the jet, there's a lot more to look at inside,
even if there are two people. Maybe even because
there are two!
Rotation
Begins
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Gulfstream
IV |
The moment the nose starts up, the PF must focus pretty
closely on the flight instruments, because the nose will quickly hide the view
of the ground and there is nothing to give a sense of attitude. Pitch too
little and the airspeed will run away, perhaps exceeding flap-speed limits, and
climb performance will suffer. Pitch too much, and you may lose airspeed,
endangering the aircraft.
Control of the attitude is fairly critical here, and most
jets have flight directors to help with this. The PNF will be monitoring all
this, to see that everything is going right, so he'll be mostly looking inside,
too. The result is that for the first 500- to 1,000-feet of climb, the typical
jet operation is highly vulnerable to "other traffic," be it birds of
the feathered kind or birds of the mechanical kind.
Van Nuys tower is probably the best in the country, and
they are very, very good at handling the mix of light aircraft using Runway
16L, and heavier stuff using 16R. The first few times they cleared me for
takeoff with a light aircraft right there, I was a bit nervous, but they handle
it so that by the time we'd hit the other aircraft, we're above it. But the
thought of a student pilot making an early right turn into us still gives me
the willies. Now transfer this operation to a busy, non-towered airport and
things get really hairy.
Van Nuys Runway 16R is also a critical noise-abatement
runway, which increases the pilot workload immensely if done "The
Gulfstream Way," so I won't use it. We rotate briskly to 20 degrees nose
up, well above the flight director, and hold that way for just a few seconds.
The altitude limit (1,700 MSL) is only 900 feet above the airport, so this one
is very easy to blow, and there is that Southwest 737 just 1,000 feet above on
the ILS to Burbank.
At about 1,100 feet (300 feet above the runway), I lower
the nose to the flight director pitch command bars, and this will produce a
nice lowering of the nose to catch 1700 feet, while automatically reducing the
thrust to hold 160 knots (manual speed). At that point we sail across the far
end of the runway and the noise monitors in level flight, very low thrust, on a
very precise track. That keeps the neighbors less unhappy (although they'll
never be happy).
Len Krugler, too. Who's Len Krugler? He's the noise boss
at Van Nuys, and works very hard to keep it as quiet as possible. Good guy.
First letter I ever got from him was something like, "Your takeoff the
other morning was within limits, but from watching a lot of G-IVs take off, I
know it can be done better." I spent the next two years getting the data
from every takeoff and experimenting with different techniques. I'm pretty quiet,
now. Well, my airplane is pretty quiet; my chief pilot thinks I make way too
much noise.
As we taxi into position on 16R, the VOR station is right
there at the threshold, so DME is an accurate measure of how far into the
takeoff we are. The far end of 16R is about 1.2 DME, and at only 2.2 DME, the
procedure is to simultaneously turn left to 110 degrees, climb to 4,000 feet,
and switch frequencies to SoCal Departure on 124.7. The PNF has to pull the
gear, set that heading, set the altitude, and push the "Flight Level
Change" button to give the PF all the proper indications, and change
frequencies and talk, too.
All this happens very, very quickly, and is rather
carefully choreographed and briefed. It must be flown with precision, which
means watching the instruments. There's just not much time left to look
outside. I wish it were not so.
I really like hand-flying, and used to do that any time
below about 10,000 feet. I've gotten away from that now, and generally turn on
the autopilot very early so that it does the precision work while I can divide
my attention between making sure it's doing what I intend and traffic watch.
This also relieves the PNF of a lot of work, so he can better watch and do his
things. Maybe Airbus has this automation thing right, after all. I'm just not
quite there yet.
The
Departure and Arrival Procedures
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Las
Vegas (KLAS) BOACH TWO departure procedure (excerpt). (Click here for larger
version -- 212 KB.) |
There are more pressures to use the automation. Take a
look at these "new" RNAV arrivals and departures.
These procedures require very high accuracy (in three
dimensions), usually demanding full-up dual FMS systems, backed up by full-time
GPS or DME-DME updating. Some operators now require them to be flown on
autopilot, and some of the DPs require flipping the autopilot on as low as 500
feet AGL after takeoff. I'm coming to agree with that, as much as I prefer
hand-flying.
Does this use of automation free up the old Mark One
eyeballs? Maybe. But pilots still need to monitor what's going on, and watching
all this magic work is seductive. Even when things are going well, the eyes
keep coming back to it -- inside.
The saving grace here is that most of this stuff takes
place in positive-control airspace of one kind or another, so "eyes
out," airmanship and hand-flying skills have become less important than
they used to be. So they say.
Old
Instruments vs. New
There are other factors that draw our eyeballs inside too
much. With the big, old, individual, mechanical altimeter, I could have my eyes
looking outside and see motion on that instrument peripherally without even
looking at it, and make a correction. Same for the airspeed and especially for
the vertical speed. Now, with the vertical tape and/or digital displays, I have
to deliberately look -- and
look hard -- at the display and
think about what it's trying to
tell me.
Kind-of like the difference between an old analog watch
and a digital. A glance at the hands tells the story, but no one glances at the
digits; they must read them. Some of the modern, glass displays have gone back
to showing a video presentation of the old style, and I think that's a good
thing. It is amazingly difficult to hand-fly a simple traffic pattern in the
G-IV. For one thing, since we rarely do it, we don't get the practice, so we're
not very good at it. Most end up just setting up the flight director to command
heading and altitude, and guess where the eyes go in that situation? Inside, of
course.
We do get to take off and land at a few uncontrolled
airports, and that is both a joy and a dread. The joy is that we can just fly
like the light piston pilots do (eyes much more outside). The dread is that
it's entirely up to us to look out for the others.
I promise, I'll try to get my eyes outside more.
Be careful, up there!