However, it also afforded the pilot the opportunity to  use the extra protected airspace to mitigate the need to  conduct a high descent rate, unstabilized approach that  was often necessary as a result of the previous criteria for  the Circling Approach Radius (CAR). For example, under  FAA Order 8260.3 Change 21, a sea level airport with  a 1,500 ft HAA will have CAT C CAR of 2.86 NM, a 1.16  NM (68.5%) increase over pre-Change 21 CAR for CAT C.  This extra protected airspace can be used by the pilot to  maneuver the aircraft instead of being forced to use high  descent rates which are often necessary for high HAA  circling approaches.  Most commercial operators dictate standard procedures for  conducting instrument approaches in their FAA-approved  manuals. These standards designate company callouts,  flight profiles, configurations, and other specific duties  for each flight deck crewmember during the conduct of  an instrument approach.  Beginning in February 2000, the FAA began issuing the  current format for instrument approach charts. This chart  was developed by the Department of Transportation  (DOT), Volpe National Transportation Systems Center and  is commonly referred to as the Pilot Briefing Information  format. The FAA chart format is presented in a logical order,  facilitating pilot briefing of the procedures. [Figure 4-3]  Individual FAA charts are identified on both the top and  bottom of the page by their procedure name (based on the  NAVAIDs required for the final approach), runway served,  and airport location. The identifier for the airport is also  listed immediately after the airport name. [Figure 4-4]  There are several types of approach procedures that may  cause some confusion for flight crews unfamiliar with the  naming conventions. Although specific information about  each type of approach is covered later in this chapter, listed  below are a few procedure names that can cause confusion.  When two or more straight-in approaches with the same  type of guidance exist for a runway, a letter suffix is added  to the title of the approach so that it can be more easily  identified. These approach charts start with the letter Z  and continue in reverse alphabetical order. For example,  consider the (RNAV) (GPS) Z RWY 13C and RNAV (RNP) Y  RWY 13C approaches at Chicago Midway International  Airport. [Figure 4-5] Although these two approaches can  be flown with a global positioning system (GPS) to the  4-9  The FAA Order 8260.3 Change 21 to the circling protected  airspace afforded much greater obstacle protection.  Prior to FAA Order 8260.3 Change 21, pilots were often  faced with the challenge of descending using a stabilized  approach concept if the CMDA height above airport  (HAA) exceeded 1,200 feet. Once the HAA approached  1,200 feet, pilots were often forced to increase their rates  of descent in order to arrive at the appropriate “in-slot”  position. “In-slot” being defined as at a minimum, a CAT C  or CAT D turbine-powered airplane should be wings level  on a three degree - 318 ft/NM descent path not less than 1  NM from the touchdown point (1,000 feet beyond runway  threshold). This was due to the small size of the circling  protected airspace that the aircrews must remain within  to ensure obstacle clearance.  A minimum of 300 feet of obstacle clearance is provided  in the circling segment. Pilots should remain at or above  the circling altitude until the aircraft is continuously in a  position from which a descent to a landing on the intended  runway can be made at a normal rate of descent and using  normal maneuvers. Since an approach category can make  a difference in the approach and weather minimums and,  in some cases, prohibit flight crews from initiating an  approach, the approach speed should be calculated and  the effects on the approach determined and briefed in  the preflight planning phase, as well as reviewed prior to  commencing an approach.  Instrument Approach Charts  Approach Chart Naming Conventions  Straight-In Procedures  Figure 4-2. Construction of circling approach area.  A  B  C  D  E  1.3  1.5  1.7  2.3  4.5  Approach category  Radius (miles)  RADII (r) defining size of areas, vary  with the approach category  Circling  approach area  r r r r r