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Chapter 10 The nature of planning and control 295
Besides the usual ‘large’ planes, controllers have to
manage the small aircraft, business helicopters, traffic
spotter planes and the many sightseeing planes flying over
Manhattan, or up the Hudson towards the Statue of Liberty.
The tower controllers have to control the movement of over
2,000 helicopters and light aircraft that fly through New
York’s airspace every day, being sure to keep them out of
the airspace around each airport used by the arriving and
departing aircraft.
Ground controllers
As an aircraft lands, it is handed over to the ground
controllers who are responsible for navigating it through
the maze of interconnecting taxiways found at most
international airports. Some airport layouts mean that
planes, having landed, have to cross over the runway
where other planes are taking off in order to get to the
terminal. All this needs careful coordination by the ground
controllers.
Some pilots may be unfamiliar with airport layouts and
need careful coaxing. Worse still is poor visibility, fog or
low cloud. At Kennedy airport, the ground radar does not
show aircraft type, so the controllers have to rely upon
memory and constant checking of aircraft position by
radio to ensure they know where each aircraft is at any
time.
Stress
Dealing continually with so many aircraft movements means
that controllers have but a split second to analyse and
react to every situation, yet they need to be right 100 per
cent of the time. Any small error or lapse in concentration
can have catastrophic consequences. They can’t afford
to lose track of a single aircraft, because it may stray into
someone else’s airspace and into the path of another aircraft.
If the computer projects that two planes are about to
fly closer than three miles, the Conflict Alert buzzer sounds
and the controllers have just seconds to make the right
decision and then transmit it to the pilots. Sometimes problems
arise in the planes themselves, such as an aircraft
running short of fuel. Emergency landing procedures cover
such eventualities. At Kennedy airport, they have about one
such incident each day. As one controller remarked, ‘It’s like
an enhanced video game, except you only have one life.’
Questions
1 What does ‘planning and control’ mean to air traffic
controllers?
2 What are the differing problems faced by TRACON,
tower and ground controllers?
3 What sequencing rules do you think the tower
controllers use?
Problems and applications
These problems and applications will help to improve your analysis of operations. You
can find more practice problems as well as worked examples and guided solutions on
MyOMLab at www.myomlab.com.
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Re-read the ‘operations management in practice’ at the beginning of the chapter, ‘Joanne manages the
schedule’, and also the short case on Air France. What are the differences and what are the similarities between
the planning and control tasks in these two operations?
A specialist sandwich retailer must order sandwiches at least 8 hours before they are delivered. When they
arrive in the shop, they are immediately displayed in a temperature-controlled cabinet. The average time that
the sandwiches spend in the cabinet is 6 hours. What is the P:D ratio for this retail operation?
It is the start of the week and Marie, Willy and Silvie have three jobs to complete. The three of them can work on
these jobs in any order. Job A requires 4 hours of Marie’s time, 5 hours of Willy’s time and 3 hours of Silvie’s
time. Job B requires 2 hours of Marie’s time, 8 hours of Willy’s time and 7 hours of Silvie’s time. Job C requires
10 hours of Marie’s time, 4 hours of Willy’s time and 5 hours of Silvie’s time. Devise a schedule for Marie, Willy
and Sylvie that details when they will be working on each job. (Assume that they work 7 hours per day.)
For the example above, what is the loading on Marie, Willy and Silvie? If all the jobs have to be finished within
2 days, how much extra time must each of them work?
Step 1 – Make a list of all the jobs you have to do in the next week. Include in this list jobs relating to your work
and/or study, jobs relating to your domestic life, in fact all the things you have to do.
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