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 aircraft have been established. These categories provide a standardized basis for relating aircraft manoeuvrability to specific instrument approach procedures.
The criteria taken into consideration for the classification of aeroplanes by categories is the indicated airspeed at threshold (Vat) which is equal to the stall speed Vso multiplied by 1.3 or stall speed Vs1g multiplied by 1.23 in the landing configuration at the maximum certificated landing mass. If both Vso and Vs1g are available, the higher resulting Vat shall be used.
Aircraft categories will be referred to throughout this document by their letter designations as follows:
| Category | Vat (km/h) | Vat (knots) |
|---|---|---|
| Category A | IAS < 169 km/h | IAS < 91 kt |
| Category B | 169 km/h ≤ IAS < 224 km/h | 91 kt ≤ IAS < 121 kt |
| Category C | 224 km/h ≤ IAS < 261 km/h | 121 kt ≤ IAS < 141 kt |
| Category D | 261 km/h ≤ IAS < 307 km/h | 141 kt ≤ IAS < 166 kt |
| Category E | 307 km/h ≤ IAS < 391 km/h | 166 kt ≤ IAS < 211 kt |
Category H is only for helicopters.
The procedures and the track protections are constructed using a predefined speed range depending on the localization inside the approach tracks.
| Aircraft Category | Vat (kt) | Speed for initial approach (kt) | Speed for final approach (kt) | Speed for final approach (kt) Maximum speed for visual manoeuvring (kt) | Maximum speed for missed approach Intermediate (kt) | Maximum speed for missed approach Final (kt) |
|---|---|---|---|---|---|---|
| A | <91 | 90/150 | 70/100 | 100 | 100 | 110 |
| B | 91/120 | 120/180 | 85/130 | 135 | 130 | 150 |
| C | 121/140 | 160/240 | 115/160 | 180 | 160 | 240 |
| D | 141/165 | 185/250 | 130/185 | 205 | 185 | 265 |
| E | 166/210 | 185/250 | 155/230 | 240 | 230 | 275 |
| H | N/A | 70/120 | 60/90 | N/A | 70/90 | 70/90 |
N/A = Not Applicable