Flight Training - May 2015 - 28

CHECKRIDE

By Bob Schmelzer

THE ABC OF AIRSPACE

IT STARTS WITH UNDERSTANDING Y

iven the complexity of our national airspace system, sometimes referred to as "alphabet airspace" because of the letter
designations assigned to each type, it isn't surprising that
many pilot applicants struggle with this challenging topic
during their practical test. Perhaps the difficulty lies not so much with
the complexity of the subject matter as
much as how we attempt to learn the
material. Faced with a seemingly endless
list of numbers, details, and facts, it might
be tempting to just rote-memorize them to
get past the checkride. Bad idea! A better
plan would be to understand why each of
the various airspace rules applies, enabling
better understanding and longer retention.
The national airspace system is mainly
designed to separate aircraft, but it also
protects pilots from themselves. Take
Class G, for example. Air traffic control
does not take place in Class G operations,
so it protects VFR pilots from themselves
by including more restrictive rules for
night operations. For VFR, adequate outside visual references must be maintained
to safely operate. During daylight hours,
it's just one mile of visibility and clear
of clouds-much tougher to do safely at
night, hence the higher night minimums.
Understanding that the boundary between Class G and the overlying
"controlled" Class E airspace is lower at

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airports with instrument approach procedures explains why higher visibility and
cloud clearance for VFR pilots above 700
feet, day or night, helps protect transitioning IFR pilots from local VFR traffic.
As an airport's traffic volume increases,
other airspace options are added to ensure
safe separation. The first one lowers
the Class E airspace to the surface. This
requires better visibility and cloud clearance down to the runway, protecting IFR
operations while still providing VFR pilots
the option to operate in less-than-required
Class E weather by obtaining a Special
VFR clearance. The night restriction
for Special VFR requiring the pilot and
aircraft to be IFR qualified and equipped is
another way these rules protect pilots.
At busier airports, the next step adds a
control tower, creating Class D airspace.
With a control tower, the new requirement becomes communication, without
which there is no direct ATC control. But
even without two-way radio communications, the tower still has access to light-gun

signals to enable limited communications.
Since this airspace is "controlled," the
same VFR visibility and cloud clearance
requirements of Class E apply. And since
the controlled airspace drops all the way
to the runway, as with all airports having
surface-controlled airspace (except many
of the busiest Class B airports-NO SVFR),
the rules associated with Special VFR
operations also apply whenever the airport
becomes IFR: ceilings below 1,000 feet
and/or visibility below three statute miles.
Adding a Terminal Radar Service Area
(TRSA) brings radar service to the safety
equation. These are almost identical, operationally, to Class C airports, but without
the requirement to participate. Communication is again the primary requirement
with the addition of a Mode C (altitudereporting) transponder within and above
Class C airspace. Even with the added
protections of radar service, ATC does not
guarantee separation between VFR and
other traffic. It's still see and avoid.
At the nation's busiest airports, Class
B services provide separation between
all aircraft. This is the only controlled
airspace in which basic VFR rules permit
"clear of clouds" operations for VFR aircraft, since ATC provides sequencing and
separation between all aircraft in Class B
airspace. Communications, Mode C transponders (within the Mode C veil), and
real-time ATC clearances are required.
At 10,000 feet above sea level and
higher-because the 250-knot speed limit
is no longer applicable-Mode C transponder, even better visibility, and greater
cloud clearance are essential to adequately
see and avoid fast-moving jet traffic while
VFR. Upon reaching 18,000 feet mean sea
level (FL180), forget about VFR: Everybody must be IFR-controlled by ATC in
Class A. See? Easy as A-B-C.
Bob Schmelzer is a Chicago-area designated pilot
examiner, a United Airlines captain, and a Boeing
777 line check airman. He has been an active flight
instructor since 1972.

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Flight Training - May 2015

Table of Contents for the Digital Edition of Flight Training - May 2015