An ILS approach was made using autothrottle. Some airlines dislike its use on
manual approaches; pitch attitude can interact with engine response with rough
handling. But an autothrottle provides good
warning of windshear. The -400's FMCdirected autothrottle interfaced steadily with
the electronic engine control on the RB.211.
Its "L" version will be equipped with fullauthority digital engine control, as are the
other two optional powerplants; the
P&W4056 and GE CF6-80C2.
Flap to 20° as glideslope approached; gear
down; flap to 25° on intercept; full 30° landing setting on descent. Configuration
changes were made in steady order, with
retrim at each change. Most trim change
occurs with landing flap selection, but the
overall effect is not rapid, and is disguised by
inertia if selection and trim adjustments are
not rushed. Electric pitch trim rate, a function of speed, feels consistent in response.
At final approach speed the attitude is 1-2°
nose up with 30° flap, so the downwards view
is good. At flare, the nose is raised only a
degree or two. Ground effect is substantial,
and the descent washes out below 100ft.
With throttles closure from 50ft, attention
was moved to the far distance. In large
aircraft, or in those with high attitude at
flare, it is difficult to picture the aircraft-toground relationship when looking down over
the nose.
A light aircraft is not the easiest to land. At
the top of the PFD, radio altitude showed
zero in my peripheral vision. Then we were
on, in a rumbling and rocking contact typical
of the multiwheel response of a 747 to untidy
contact. The automatic ground spoilers
induced a slight nose-up counter to the
lowering nosewheel that is a feature of the
747.
Flap to 20°; trim adjusted; throttles stood
up for a touch and go. The next circuit
showed the PFD assisting crew co-operation.
Joe
wanted
another
cockpit
noise
measurement run. Sound insulation is
improved, and cockpit noise levels seem very
low below 250kt; the engines are distant, and
the curved windscreens match the nose
upflow.
In a visual circuit with manual throttle
"hand taps" were used in absolute silence,
and flap was lowered as speed reduced below
the manoeuvring value for the previous
setting. The hollow datum speed arrow was
placed each time to frame the flap number
marking the next manoeuvring speed.
Speeds for just the current and next-up flap
setting are marked on the speed scale, so it is
not cluttered. (In acceleration, flap is
retracted as the speed for the next higher
setting is reached.)
The non-precision approach was kept in
the slot by the clear vertical speed indicator
display. A 6,000ft /min maximum scale
expands below 2,000ft/min, particularly
below 1,000ft/min, and the needle angles
away from centre to help judgement. Rate is
30
747 performance summary
Typical international rules, three-class interors
Engines
Passengers (First class/Business/
Tourist)
Cargo (pallets/cont.)
SLST/F.R.temp (lb/T)
Fuel capacity (US gal)
Rolls-Ro-ce RB.211-524G General Electric CF6-80C2 Pratt & Whitney PW4056
Weights (lb)
Max takeoff
Max landing
Max zero fuel
Operating empty
Basic
800,000
574,000
535,000
393,000
Option
850,000
630,000
535,000
393,700
6,300
9,200
34,000
6,250
7,110
10,800
32,800
6,950
7,370*
11,450
32,100
6,950
6,320
9,200
34,100
6,250
7,130
10,800
32,800
6,950
143
152
152
143
152
303-2
303-5
303-5
305-5
305-9
Design range (n.m.)
Takeoff field length (ft)
Init. cruise altitude (MTOW) (ft)
Landing field length (MLW) (ft)
Approach speed (MLW) (kt)
Block fuel/passenger,
3,000 n.m. mission (lb)
Fuel capacity limit
412(34/76/302)
5/14
58,000/86
53,985 57,285 57,285
412(34/76/302)
5/14
57,900/90
53,711 57,011 57,011
Option Basic
870,000 800,000
630,000 574,000
535,000 535,000
393,800 389,400
read at the bottom or top of the scale. The
nominal 600-700ft/min for a 3° approach
coincides with a cutout for the altitude digits
alongside.
This next touchdown felt good; the sound
recording registered only the autospoiler
running. The next circuit was made with
engines three and four at idle, to a go-around
from 700ft. Bank was limited to 15°. The
configuration is kept at 10° flap and gear up,
flying at V REF +30kt, until a landing is
assured.
The light aircraft was slippery in speed.
Too much attention was paid to retrim with
descent and power changes. The slip indicator, a bar that slides under the roll datum
of the PFD, is compelling on the larger
display. "It is best to fix your feet, hold it, and
just attend to the throttles," said Joe.
I reached that 158kt target speed for goaround. The rudder pedal was not quite fully
deflected, but I put the wing down slightly
into the live engines as a precaution. The
manual says that a little thrust may need to be
shed from an outer engine if the speed drifts
low. But there was margin in control; the
increase in rudder throw from 25° to 30°
doubtless helped.
Toga operation is well thought out. It is
armed automatically at glideslope capture or
flap selection, and is ready to apply full
power if neither autopilot or flight director
is engaged. Otherwise a single push on a
Option
850,000
630,000
535,000
390,100
Option
870,000
630,000
535,000
390,200
412 (34/76/302)
5/14
56,750/86
53,985 57,285 57,285
Basic
800,000
574,000
535,000
390,200
Option
850,000
630,000
535,000
390,900
Option
870,000
630,000
535,000
391,000
6,320
9,150
34,100
6,450
7,120
10,700
32,800
7,000
7,340
11,400
32,300
7,000
152
143
152
152
305-9
304-4
304-8
304-8
7,290*
11,450
32,300
6,950
trigger will demand sufficient climb power
for a 2,000ft/min climb. Full power is available on a second push.
There was just time for some mid-altitude
handling on the return to Seattle. The 12ft of
extra span and the winglets seem to make no
difference. Dutch roll, at 210kt with yaw
dampers off, was a wallow typical of big
aircraft. It was easily stopped, with a
moment's hesitation, by holding the control
wheel gently against the roll. A 10° sideslip
could be held with light rudder—steadily, if
I braced my feet and avoided fidget on the
controls.
Beyond 45° of bank a lot of pull and rudder
is needed for level turns. Bank angle excess
is usefully warned by voice. Roll reversals
through 60° were slick for a wingspan of
213ft. The wing did rumble at full aileron
and roll spoiler deflection, and in initiating
or stopping turns when flying just lOkt above
stick shaker speed.
With a sky full of cloud, stall approaches
were recovered at stickshaker. At the yellowlined manoeuvre speed, 747 inertia was felt
in turns, but could be held with the effective
controls. In clean recovery, from 165kt at
440,0001b, the impending shaker warning
was marked as a red-lined speed range on the
PFD.
An extra warning appears on the PFD
when flaps are out: a pitch limit indicator on
the horizon shows stickshaker pitch attitude
FLIGHT INTERNATIONAL, 12 November 1988