AIRLINER

Written by R. Hopkins
This program is an accurate simulation of
the flying characteristics of an airliner. You
can take off, manoeuvre, navigate and land
the aircraft using normal aircraft controls.
You can find your present position on a
map or view the runway as you land without
losing sight of your vital instruments.
Load this program with LOAD"" or LOAD
"Airliner". If you have any difficulty, refer to
pages 141 -148 in the Sinclair ZX Spectrum
handbook. The program loads in five parts,
wait until the instrument panel is fully drawn
and coloured, and the first prompt is written
on the screen before stopping your
recorder. It is advisable to read all these
notes before running the programs as this
aircraft simulation is as complex as an
aircraft itself.

FLYING TECHNIQUE

Flying the aircraft involves a balance
between the flight controls and the throttle
settings. By pushing the joystick forward or
pressing the up key (on the 7 key), the
aircraft will dive and its speed will increase.
To keep the speed constant, therefore, the
power setting must be decreased.

Conversely, pulling the joystick back or
pressing the down key (on the G key) will cause
the aircraft to climb and slow down,
needing an increase in power setting to
keep the speed constant. Left and right
movements of the joystick or pressing
the <- or -> keys (on the 5 and 8 keys)
makes the aircraft bank and turn to the left
and right respectively.

As the speed drops, the aircraft
approaches an out of control or stall
condition. Flaps allow the aircraft to delay
the onset of this condition allowing the
aircraft to fly slower without stalling. Flaps
also cause more drag on the aircraft so that
when the flaps are deployed power setting
will need to be adjusted to stop the speed
falling off at too great a rate. Flaps will be
needed to give lift at the slow speed
available at take off. Take off will not be
achieved at speeds less than 100 knots.

To land the aircraft, try to approach on a
glide path losing height at 600-800 feet a
minute. The head down display (11 on fig. 1)
will indicate permission to land by showing
the runway if your approach is viable, that
is within ± 10 of the runway centreline.
Brake as fast as possible after landing, i.e.
altitude less than 10 ft., as the runway is not
infinitely long. If you attempt to land with
your undercarriage up the 'G' on the GEAR
will flash to warn you.

THE INSTRUMENT PANEL

The instrument panel of your aircraft is
shown in fig. 1.  (See file instruments.jpg). 

The individual instruments
are as follows:

1. Airspeed Indicator: Your airspeed in
knots.

2. Heading Readout: Your direction of
fliqht in degrees.
0 or 360 is due north, 180 is due south,
90 and 270 are east and west
respectively. Use this in conjunction
with the map to find out where you are
heading at present.

3. Power Meter: Shows the power
setting of your engines. More power will
increase both the speed of your aircraft
and the aircraft lift, so if you are
approaching an out of control situation
(see 8) more power will help you
retrieve your situation. The control
works like a throttle, pressing P will
start the power increasing or stop the
power decreasing, pressing 0 will
decrease the power or stop the power
increasing.

4. Flap Indicator: Shows the angle of
flaps you have deployed in degrees.
The more flap you have out, the more
lift you get, but also you get more drag
so you must increase your power to
stay at the same speed. Pressing K (+)
gives more flap, J(-) less flaps.

5. Brake Indicator: Shows if the brakes
are on or off. To change this, press B.
Note that brakes do not work when
you are airborne!

6. Undercarriage Indicator: Shows if
your undercarriage is down or up.

7. Fuel Indicator: As you fly, your fuel is
used up in proportion to the power
developed by the engine. A reserve
tank, with a fifth of the capacity of the
main tank, will be automatically
switched in when the main supply is
used up.

8. Control Indicator: If the aircraft is
heading towards an out of control
situation, then the C on this instrument
will flash. You must quickly increase
speed, flaps and power to recover
control.

9. Rate of Climb/Descent Meter:
Shows the rate of climb of the aircraft. If
the aircraft is descending, the ROC,
rate of climb, legend will change to
ROD, rate of descent. The upper figure
is the number of thousands of feet, the
lower is hundreds of feet.

10. Altimeter: Shows the aircraft's altitude
in feet above the ground. Like the Rate
of Climb indicator, the top figure is
thousands of feet, the lower hundreds
of feet.

11. Head Down Display: This CRT (Cathode
Ray Tube) functions three modes.

(i) Attitude Indicator: Sometimes called an
artificial horizon, the attitude of the
aircraft is shown, the plane being
viewed from the tail over a horizon that
moves depending on roll, attitude and
lift. The display defaults to this mode. '

(ii) Map If M is pressed the display
changes to a map, showing the runway
approach beacons in the centre and all
the navigation beacons around it. The
map is shown in fig. 2. Also shown is
the present position of your aircraft.
Provided your present position is within
the confines of the map, it will be shown
as a dot within a flashing square. Whilst
the map is selected, the position is not
updated. Pressing M again reverts the
display to the attitude indicator.

(iii) Runway View: If you fly over one of the
two approach beacons, EDN or UWB,
on a viable course for landing i.e. within
± 10° of the runway centreline, the CRT
will clear to show a view of the runway,
indicating acceptance for landing. At
this point an altitude of 750ft. is ideal
with a rate of descent of 600- 800ft./
min. At the far end of both runways a
set of airport buildings will be seen.
They are 1.2m from the opposite
approach beacon.

12. Attitude and Roll Meters: These
readouts indicate the attitude of the
aircraft more accurately than the
artificial horizon (See 11 (i)). Attitude is
negative when the nose is down roll is
negative when turning to port (left).

13. Navigation Panel: The three letter
mnemonic is used to refer to the
beacon onto which your navigation
system has locked. EDN refers to
Edinburgh whilst PTH refers to Perth
(See fig. 2). (See file navigation.jpg)

Beside the beacon
mnemonics the radial angle of the
aircraft is displayed, this is the angle an
observer at the beacon must look along
to see the aircraft. To the right of the
navigation panel, a head up display
shows, using a flashing dot, the
direction of the current beacon with
respect to the aircraft heading, i.e. it
shows the direction the pilot must look
to see the beacon.

USING THE PROGRAM

After loading you will be asked if you wish
to take off or not, answering 'Y' will position
you at the end of the runway with your
engines running. Just set your flaps,
increase the power and you will roll down
the runway. You cannot take off at a speed
less than 100 knots, and a firm pull back on
the joystick is required. Once you are
airborne, you can navigate a route across
country, manoeuvre and find your way back
to the airport as you would in a real aircraft.
However watch your fuel.

If you opt for the flying option, answer 'N' to
the take off option. You will be asked to
choose your altitude at which you wish to
be placed. Enter the altitude in feet.

Next is the option for wind effects. Wind
direction must be entered in degrees from
North. Wind speed is entered in knots.
Wind will make your aircraft drift from its
predicted course. You will need to be fairly
experienced to cope with wind, so if you
don't want any wind effect, enter the wind
direction and windspeed as 0.

The next option is to define your position or
accept a random position. The computer
will give the position if you answer 'N', and
you will then be flying at your chosen
altitude.

If you wish to place yourself, first define a
beacon by its three letter mnemonic, then
your radial position from it in degrees, your
aircraft heading in degrees from north and
the distance, DME, from your chosen
beacon. You need not position yourself on
the map, but ensure that you have enough
fuel to fly to the airport.

If you want to practice landing, answer the
last set of prompts with

ALTITUDE? 1100      BEACON? EDN
RADIAL?    70      HEADING? 250
DME?       5

You will now be positioned on the glide
path, five miles from the runway beacon.
Drop your speed, deploy your flaps, drop
your undercarriage and dive at 600-800ft./
min. and you should land smoothly.
Remember to brake on touchdown.

®1983 PROTEK COMPUTING LTD.,

Clydesdale Bank Buildings,
High Street,
South Queensferry,
EH30 9HW.

Cover and illustrations by George Neill.
Diagrams and text paste-up by lain McKinlay