Traffic Pattern Speeds
Traffic pattern speeds are of primary interest since most of your duties are in terminal
control facilities. A very important portion of the traffic pattern is the final approach
course. That is where most accidents or incidents occur. They are usually the result of
an incorrect sequencing technique, failure to issue timely information, or failure to
consider approach speeds when a landing sequence is issued.
The following example was an actual incident:
A T-34C was "cleared touch-and-go‖ by the tower. The T-34C was executing a
normal VFR approach at approximately 100 knots. A pilot of a FA-20 was
executing a PAR approach. The FA-20 was "cleared to land‖ by the tower via
GCA. The T-34C pilot acknowledged the ―clearance for a touch-and-go‖ but
failed to hear a second transmission sequencing them behind the FA-20 due to
frequency congestion. With both aircraft on final approach, the FA-20 was waved
off, passing directly over the T-34C at about 100 feet. The T-34C touched down
on the runway and lifted off again after their touch-and-go landing.
The two aircraft had dissimilar airspeeds (the FA-20 being much faster) and descent
rates. Due consideration must be given to approach speeds and other operational
characteristics when initial landing sequences are assigned.
Aircraft Climb and Descent Rates
Air Traffic Controllers often need to direct pilots to make altitude changes to maintain
proper separation between flights. Therefore, you should have some idea of what
performance rates are within the capability of certain aircraft.
Climb and Descent Rates
Conventional-type aircraft climb/descent rates vary from 500 fpm to 2,000 fpm, whereas
jets climb/descent rates vary from 3,000 fpm to 5,000 fpm. These rates reflect normal
operating ranges and should not be confused with maximum performance rates. Air
traffic control (ATC) related factors such as weather, type of flight, and fuel status must
also be considered when you are anticipating separation based on the normal climb or
descent characteristics of aircraft.
Consider a departure controller directing a departing aircraft to a fix where existing
conditions require that the aircraft be at a specified altitude before reaching this fix. If
the flight were an air evacuation flight with patients aboard, its rate of climb would
certainly be lessened. The controller should recognize this fact. Instead of "driving" the
aircraft straight to the fix, the controller should determine, by asking the pilot, if the
altitude can be reached and should be responsive to any request for more climbing
time.
It is imperative that you apply good control techniques and judgment and be aware of
the operating parameters of the different aircraft that you are responsible for.
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