Maximum Secure Descent Speed for an Instrumental Landing Approach

Maximum Secure Descent Speed for an Instrumental Landing Approach

In the world of aviation, maintaining a stable and safe approach is paramount, especially during instrument approaches. At Crookston's (KCKN) VOR/DME Approach to Runway 13, the lowest Minimum Descent Altitude (MDA) takes you to 344 feet above the Touchdown Zone Elevation (TDZE). To ensure obstacle clearance, a stable approach path, and manageable pilot workload, the Federal Aviation Administration (FAA) recommends maintaining a descent rate below approximately 1,000 feet per minute during the final stages of an instrument approach.

This recommendation is supported by several key points. The standard 3-degree glide slope used for instrument approaches corresponds roughly to a descent rate of 478 feet per minute at 90 knots groundspeed, providing a smooth, stable descent path that keeps you clear of terrain and obstacles. Descent rates significantly higher than this make it harder to maintain stable flight and precise vertical control.

FAA guidance and published instrument approach procedures specify altitudes and glide slope intercept points to ensure required obstacle clearance during descent. Following these published paths naturally encourages moderate descent rates consistent with safety margins, typically well under 1,000 feet per minute.

Excessive descent rates, such as 1,500 feet per minute or more, are generally discouraged in final approach because they increase the risk of unstable approaches and hard landings. Maintaining lower descent rates reduces pilot workload in controlling airspeed and configuration changes, increases time to recognize and correct errors, and aligns with safe approach speed profiles recommended for the aircraft and approach type.

In the general aviation world, approaching a 1,000 feet per minute descent rate likely indicates instability. In such cases, it is advisable to go missed and try the approach again. To find the approximate distance where you would start a descent from MDA to the runway, divide the AGL value of the MDA by 300.

It's worth noting that not every non-precision approach will have a "V" published, but reaching the Vertical Descent Point (VDP) allows you to follow a 3-degree glide path to the runway, which is the same glide path as most precision approaches. Approximately 1.15 is the distance from the runway where you can start a 3-degree descent to the runway on the Crookston (KCKN) VOR/DME Approach to Runway 13.

For short runways, arriving at the MDA at the runway threshold may require a missed approach, as it means you're still several hundred feet above the runway, making a safe landing difficult. Operational practices and techniques should ensure that descent rates greater than 1,000 feet per minute are not permitted in either the instrument or visual portions of an approach and landing operation.

Continuously exceeding 1,000 feet per minute on an instrument approach is considered unstable at most airlines. Momentary deviations above 1,000 feet per minute are allowed, however. Sustained descent rates over 1,000 feet per minute are unstable on approach. The FAA considers a descent rate exceeding 1,000 feet per minute unacceptable during the final stages of an approach.

In conclusion, maintaining a descent rate below 1,000 feet per minute during instrument approach final stages is crucial for a safe and stable approach and landing. This rate varies somewhat with groundspeed, but generally, a 3-degree glide slope or gentler descent gradient corresponds to about half that descent rate at common approach speeds. If obstructions penetrate safety clearance tolerances during the creation of an approach, a VDP might be denied, emphasising the importance of adhering to these guidelines.

1. In the aviation world, maintaining a descent rate below 1,000 feet per minute during the final stages of an instrument approach is essential for a safe and stable approach and landing.
2. The standard 3-degree glide slope used for instrument approaches is approximately half the recommended 1,000 feet per minute descent rate at common approach speeds.
3. To ensure obstacle clearance, stable approach paths, and manageable pilot workload, the Federal Aviation Administration (FAA) recommends following published instrument approach procedures and maintaining a descent rate below 1,000 feet per minute during the final stages of an instrument approach.
4. Approaching a 1,000 feet per minute descent rate in general aviation likely indicates instability, and in such cases, it is advisable to go missed and try the approach again.
5. Maintaining lower descent rates reduces pilot workload, increases time to recognize and correct errors, and aligns with safe approach speed profiles recommended for the aircraft and approach type.
6. Excessive descent rates, such as 1,500 feet per minute or more, are generally discouraged in final approach because they increase the risk of unstable approaches and hard landings.
7. For short runways, arriving at the MDA at the runway threshold may require a missed approach, as it means you're still several hundred feet above the runway, making a safe landing difficult.
8. In the world of aviation, continuously exceeding 1,000 feet per minute on an instrument approach is considered unstable at most airlines.
9. If obstructions penetrate safety clearance tolerances during the creation of an approach, a Vertical Descent Point (VDP) might be denied, emphasizing the importance of adhering to FAA guidelines and recommended descent rates.

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