Approach Categories

Instrument Procedures

Eddie sez:

Your approach category deals with more than just the circling approach. It determines your maximum speeds, maneuvering airspace, and obstacle clearance on approach as well as missed approach. It is always based on your maximum certificated landing weight, though that can be changed through manufacturer approved maintenance logbook action. The speed that is used might be different between ICAO and U.S. FAA, depending on aircraft.

The United States FAA used to subscribe to a dangerously narrow circling approach area that has killed and will kill again if you don't understand the problem. (See Circling Approach Area for more about this.) The case of Air China 129 is one where a Boeing 767 was trying to circle to what were TERPS standards back then and ended up losing the airplane and 129 lives. TERPS standards have since changed but many U.S. circling procedures have not.

So what's the bottom line here? You need to understand exactly what your aircraft's circling capability is, what the correct approach category is, when you can change it, and what all that gives you for any particular airport.

Everything here is from the references shown below, with a few comments in an alternate color.

Last revision:

2020-12-28


Approach Category Determination

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Photo: Circling at Hilo, Hawaii
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United States

[14 CFR 97.3] Aircraft approach category means a grouping of aircraft based on a speed of VREF, if specified, or if VREF is not specified, 1.3VSO at the maximum certificated weight. VSO, and the maximum certificated landing weight are those values as established for the aircraft by the certification authority of the country of registry.

These categories are as follows:

  • Category A: Speed less than 91 knots
  • Category B: Speed 91 knots or more but less than 121 knots
  • Category C: Speed 121 knots or more but less than 141 knots
  • Category D: Speed 141 knots or more but less than 166 knots
  • Category E: Speed 166 knots or more

There are some who would argue that maximum certificated weight only applies to 1.3VSO based on the placement of a comma in the regulation. The debate raged on for decades but the FAA finally provided some clarity in 2013:

[14 CFR 97.3 Interpretation]

  • This memorandum is in response to your request for legal interpretation on the meaning of "aircraft approach category" as defined 14 C.F.R. § 97.3 dated September 24,2012. Specifically you ask if the phrase "maximum certificated landing weight" as used in § 97.3 applies to aircraft grouped by speed of VREF. The answer to your question is "yes" the phrase "maximum certificated landing weight" applies to both aircraft grouped by speed of VREF as well as aircraft grouped by 1.3 VSO.
  • In 1972 the FAA implemented the U.S. Standard for Terminal Instrument Procedures (TERPS). The TERPS rule changed the way the FAA defined aircraft approach categories from one based on the number of engines to new criteria based on stall speed in landing configuration or aircraft weight. Specifically "aircraft approach category" was defined as a "grouping of aircraft based on a speed of 1.3 VSO (at maximum certificated landing weight) or on maximum certificated landing weight." See 32 Fed. Reg. 13909,13911-12 (Oct 6, 1967); 32 Fed. Reg. 6938, 6939 (May 5, 1967). Section 97.3 was amended later to remove the option for basing aircraft approach categories strictly on maximum certificated landing weight. See 44 Fed. Reg. 15659 (Mar. 15, 1979). The only remaining way to make this determination was "1.3 VSO (at maximum certificated landing weight)." Id.
  • In 1996 the FAA proposed replacing "1.3 VSO" with "VREF" in the definition of "aircraft approach category" in § 97.3. See 61 Fed. Reg. 1260, 1263 (Jan. 18, 1996). The proposed definition specified that aircraft would be grouped "based on a speed of VREF at the maximum certificated landing weight." Id. at 1268. After additional review, the FAA determined that application of the VREF standard "to aircraft certificated using VS could cause confusion for users of the airspace system and that some airplane flight manuals would not be consistent with the new VREF terminology. See 67 Fed. Reg. 70812, 70822 (Nov. 26, 2002). Therefore, the FAA revised § 97.3 in the final rule to "continue to reference 1.3 VSO for use in those cases where VREF is not specified." Id.
  • The regulatory history demonstrates that the FAA intended the "maximum certificated landing weight" qualifier to apply to aircraft for which either VREF or 1.3 VSO are used to determine approach category. The new VREF standard as proposed in 1996 required "maximum certificated landing weight" to be part of the determination. The FAA revised the final rule so that aircraft approach categories could still be determined using the existing "1.3 VSO at maximum certificated landing weight" standard in addition to the VREF standard proposed in the NPRM. The preamble to the final rule contained no discussion of removing the reference to maximum certificated landing weight for the VREF standard proposed in the NPRM. We therefore conclude that for aircraft grouped by speed of VREF aircraft approach category must be determined using speed of VREF at the maximum certificated landing weight.

International

[ICAO Doc 8168 PANS-OPS Vol 1, §4, ¶1.4]

1.4.1 Aircraft performance has a direct effect on the airspace and visibility required for the various manoeuvres associated with the conduct of instrument approach procedures. The most significant performance factor is aircraft speed. Accordingly, categories of typical aircraft have been established.

1.4.2 The criterion taken into consideration for the classification of aeroplanes by categories is the indicated airspeed at threshold (Vst).

1.4.3 Aircraft categories will be referred to by their letter designations as follows:

  • Category A: less than 169 km/h (91 kt) indicated airspeed (IAS)
  • Category B: 169 km/h (91 kt) or more but less than 224 km/h (121 kt) IAS
  • Category C: 224 km/h (121 kt) or more but less than 261 km/h (141 kt) IAS
  • Category D: 261 km/h (141 kt) or more but less than 307 km/h (166 kt) IAS
  • Category E: 307 km/h (166 kt) or more but less than 391 km/h (211 kt) IAS
  • Category H: see 1.4.7, “Helicopters”.

These speeds are the same as used in the United States but the criteria is slightly different. If you have a VSO and a VS1G for your aircraft, you must use the higher of VSO times 1.3 or VS1G times 1.23.

Regardless of the speed used, it must be based on the aircraft's maximum certificated landing mass.

More on this below under The Variable Approach Category Mess.

Maximum Speeds During Approach

While the speeds used for determining approach categories are based on maximum certificated landing weight, the maximum speed actually used for approach can be different. But must it be different?

What AIM used to say . . .

[Aeronautical Information Manual §5-4-7] A pilot must use the minima corresponding to the category determined during certification or higher. Helicopters may use Category A minima. If it is necessary to operate at a speed in excess of the upper limit of the speed range for an aircraft's category, the minimums for the higher category must be used. For example, an airplane which fits into Category B, but is circling to land at a speed of 145 knots, must use the approach Category D minimums. As an additional example, a Category A airplane (or helicopter) which is operating at 130 knots on a straight-in approach must use the approach Category C minimums. See the following category limits:

  1. Category A: Speed less than 91 knots.
  2. Category B: Speed 91 knots or more but less than 121 knots.
  3. Category C: Speed 121 knots or more but less than 141 knots.
  4. Category D: Speed 141 knots or more but less than 166 knots.
  5. Category E: Speed 166 knots or more.

What AIM says now (as of 28 December 2020) . . .

For as long as I have been flying the rule has been that if you bump into the next category's speed range, you must go into the next category. It is no longer a "must" but now it is a "should."

[Aeronautical Information Manual §5-4-7]

  1. Aircraft approach category means a grouping of aircraft based on a speed of VREF at the maximum certified landing weight, if specified, or if VREF is not specified, 1.3VSO at the maximum certified landing weight. VREF, VSO, and the maximum certified landing weight are those values as established for the aircraft by the certification authority of the country of registry. A pilot must maneuver the aircraft within the circling approach protected area to achieve the obstacle and terrain clearances provided by procedure design criteria.
  2. In addition to pilot techniques for maneuvering, one acceptable method to reduce the risk of flying out of the circling approach protected area is to use either the minima corresponding to the category determined during certification or minima associated with a higher category. Helicopters may use Category A minima. If it is necessary to operate at a speed in excess of the upper limit of the speed range for an aircraft’s category, the minimums for the higher category should be used. This may occur with certain aircraft types operating in heavy/gusty wind, icing, or non−normal conditions. For example, an airplane which fits into Category B, but is circling to land at a speed of 145 knots, should use the approach Category D minimums. As an additional example, a Category A airplane (or helicopter) which is operating at 130 knots on a straight−in approach should use the approach Category C minimums.
  3. A pilot who chooses an alternative method when it is necessary to maneuver at a speed that exceeds the category speed limit (for example, where higher category minimums are not published) should consider the following factors that can significantly affect the actual ground track flown:
    1. Bank angle. For example, at 165 knots groundspeed, the radius of turn increases from 4,194 feet using 30 degrees of bank to 6,654 feet when using 20 degrees of bank. When using a shallower bank angle, it may be necessary to modify the flightpath or indicated airspeed to remain within the circling approach protected area. Pilots should be aware that excessive bank angle can lead to a loss of aircraft control.
    2. Indicated airspeed. Procedure design criteria typically utilize the highest speed for a particular category. If a pilot chooses to operate at a higher speed, other factors should be modified to ensure that the aircraft remains within the circling approach protected area.
    3. Wind speed and direction. For example, it is not uncommon to maneuver the aircraft to a downwind leg where the groundspeed will be considerably higher than the indicated airspeed. Pilots must carefully plan the initiation of all turns to ensure that the aircraft remains within the circling approach protected area.
    4. Pilot technique. Pilots frequently have many options with regard to flightpath when conducting circling approaches. Sound planning and judgment are vital to proper execution. The lateral and vertical path to be flown should be carefully considered using current weather and terrain information to ensure that the aircraft remains within the circling approach protected area.
  4. It is important to remember that 14 CFR Section 91.175(c) requires that “where a DA/DH or MDA is applicable, no pilot may operate an aircraft below the authorized MDA or continue an approach below the authorized DA/DH unless 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 using normal maneuvers, and for operations conducted under Part 121 or Part 135 unless that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing.”
  5. See the following category limits:
    1. Category A: Speed less than 91 knots.
    2. Category B: Speed 91 knots or more but less than 121 knots.
    3. Category C: Speed 121 knots or more but less than 141 knots.
    4. Category D: Speed 141 knots or more but less than 166 knots.
    5. Category E: Speed 166 knots or more.

NOTE−VREF in the above definition refers to the speed used in establishing the approved landing distance under the airworthiness regulations constituting the type certification basis of the airplane, regardless of whether that speed for a particular airplane is 1.3 VSO, 1.23 VSR, or some higher speed required for airplane controllability. This speed, at the maximum certificated landing weight, determines the lowest applicable approach category for all approaches regardless of actual landing weight.

In the U.S., the maximum speed for determining an approach category is also the maximum speed for maneuvering. If the pressure altitude, winds, temperature, or any other factor requires you to increase your maneuvering speed, your turn radius goes up and the obstacle clearance is no longer guaranteed. You should increase your approach category.

What the ICAO Says

[ICAO Doc 8168 PANS-OPS Vol 1 §4, Table I-5-1-2]

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While the speed ranges used to determine an aircraft's approach category are identical to 14 CFR 97.3, ICAO Doc 8168 PANS-OPS Vol 1 §4, ¶1.3.5, the maximum permitted speed for visual maneuvering is significantly higher. Additionally, speed ranges are specified for other segments of the approach. While it is true the speeds permitted are higher, the circling approach area is larger too.

See Circling Approach Area for more about this.

Maximum Glide Path Angles

The maximum glide path angle depends on vertical guidance.

If you have vertical guidance and are flying a PA or BARO NAV approach, the maximums are listed as follows:

[TERPS, ¶2-6-2, Table 2-6-1] GPAs must not exceed the values specified in table 2-6-1.

Category GPA
A (80 knots or less) 6.4
A (81 - 90 knots) 5.7
B 4.2
C 3.6
D & E 3.1

The Variable Approach Category Mess

We used to say you can move your category up, but never down. Alas, that isn't really true. In the case of the T-38, we thought of ourselves as Category E unless we were light enough to be Category D. Not too long ago most Gulfstreams had Aircraft Service Changes that allowed the pilots to simply turn a placard in the cockpit to magically change from Category D to Category C. The FAA got wind of this and those days are over. Now, for us civilians, there is just one recognized method of lowering approach categories.

Legally Changing Maximum Certificated Landing Weight

The FAA allows operators to legally reduce an aircraft's maximum certificated landing weight which allows them to reduce to a lower approach category. This is not something a pilot can do, it requires maintenance logbook action. In the case of the G450, for example, Gulfstream Aircraft Service Change 007 must be installed. Once that is done, the aircraft's maximum landing weight drops from 66,000 lbs to 58,500 lbs and the aircraft becomes Category C. To undo this action, the ASC must be legally removed from the aircraft by logbook action. Some would say even the paperwork instituting ASC 007 must be physically removed from the airplane.

More on this at: G450 Approach Category.


See Also:

14 CFR 97, Title 14: Aeronautics and Space, Standard Instrument Procedures, Federal Aviation Administration, Department of Transportation

14 CFR 97.3 Interpretation, AFS-400, 2013

Aeronautical Information Manual

Gulfstream G450 Aircraft Service Change 007C, Maximum Landing Gross Weight, 58,500 pounds, Category C, Provisions, October 26, 2011

ICAO Doc 8168 - Aircraft Operations - Vol I - Flight Procedures, Procedures for Air Navigation Services, International Civil Aviation Organization, Sixth Edition, 2018

United States Standard for Terminal Instrument Procedures (TERPS), Federal Aviation Administration 8260.3B CHG 25, 03/09/2012